U.S. patent application number 12/055235 was filed with the patent office on 2008-09-25 for extended therapeutic effect ocular implant treatments.
This patent application is currently assigned to ALLERGAN, INC.. Invention is credited to David A. Weber, Scott M. Whitcup.
Application Number | 20080233172 12/055235 |
Document ID | / |
Family ID | 35187366 |
Filed Date | 2008-09-25 |
United States Patent
Application |
20080233172 |
Kind Code |
A1 |
Whitcup; Scott M. ; et
al. |
September 25, 2008 |
EXTENDED THERAPEUTIC EFFECT OCULAR IMPLANT TREATMENTS
Abstract
Methods for treating ocular conditions by inserting an implant
comprising an active agent into an ocular site of a patient thereby
obtaining an amelioration of a symptom of the ocular condition
(i.e. a therapeutic effect) for an extended period of time during
which a therapeutic amount or a detectable amount of the active
agent is not present at the ocular site.
Inventors: |
Whitcup; Scott M.; (Laguna
Hills, CA) ; Weber; David A.; (Danville, CA) |
Correspondence
Address: |
Stephen Donovan;Allergan, Inc.
2525 Dupont Drive
Irvine
CA
92612
US
|
Assignee: |
ALLERGAN, INC.
Irvine
CA
|
Family ID: |
35187366 |
Appl. No.: |
12/055235 |
Filed: |
March 25, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10837357 |
Apr 30, 2004 |
|
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12055235 |
|
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Current U.S.
Class: |
424/427 ;
514/180 |
Current CPC
Class: |
A61K 9/0024 20130101;
A61K 39/3955 20130101; A61K 31/57 20130101; A61K 31/165 20130101;
A61K 9/1647 20130101; A61P 27/00 20180101; A61F 9/0017 20130101;
A61K 47/34 20130101; A61K 9/0051 20130101; A61P 29/00 20180101;
C07K 16/18 20130101; A61P 27/02 20180101; C07K 16/22 20130101; A61K
31/56 20130101 |
Class at
Publication: |
424/427 ;
514/180 |
International
Class: |
A61F 2/00 20060101
A61F002/00; A61K 31/56 20060101 A61K031/56 |
Claims
1. A method for treating an ocular condition, the method comprising
the steps of: (a) inserting an implant into an ocular site of a
patient with an ocular condition, the implant comprising (i) an
active agent, and (ii) a carrier associated with the active agent;
(b) releasing substantially all of the active agent from the
implant, and; (c) obtaining an improvement in the ocular condition
at a time when a therapeutic amount of the active agent is not
present at the ocular site.
2. The method of claim 1, further comprising the step of
maintaining the improvement in the ocular condition for an extended
period of time during which a therapeutic amount of the active
agent is not present at the ocular site.
3. The method of claim 2, wherein the releasing step occurs over a
first period of time X, and the subsequent extended period of time
during which an improvement in the ocular condition is maintained,
although a therapeutic amount of the active agent is not present at
the ocular site, is a second period of time between 0.5.times. and
100.times..
4. The method of claim 1, wherein the active agent is an
anti-inflammatory agent.
5. The method of claim 1, wherein the carrier is a bioerodible
polymer.
6. The method of 1, wherein the implant has a weight between about
1 .mu.g and about 100 mg.
7. The method of claim 1, wherein the implant has no dimension less
than about 0.1 mm and no dimension greater than about 20 mm.
8. The method of claim 1 wherein the improvement of the ocular
condition is determined by observing an improved visual acuity.
9. The method of claim 1 wherein the improvement of the ocular
condition is determined by observing an improved visual contrast
sensitivity.
10. The method of claim 1 wherein the improvement of the ocular
condition is determined by observing a decreased retinal or
choroidal blood vessel leakage.
11. The method of claim 1 wherein the improvement of the ocular
condition is determined by observing a decreased retinal or macular
thickness.
12. The method of claim 1, wherein the improvement in the ocular
condition occurs at a time when a detectable amount of the active
agent is not present at the ocular site.
13. The method of claim 1, wherein the ocular site is the
vitreous.
14. The method of claim 1, wherein the active agent is
dexamethasone.
15. The method of claim 3, wherein the first period of time is
between about 30 days and about 40 days.
16. The method of claim 3, wherein the first period of time is
about 35 days.
17. The method of claim 15, wherein the second period of time is
between about 30 days and about 180 days.
18. A method for treating a chronic ocular condition, the method
comprising the steps of: (a) inserting an implant into an ocular
site of a patient with an ocular condition, the implant comprising
(i) an active agent, and (ii) a carrier associated with the active
agent; (b) releasing substantially all of the active agent from the
implant; (c) obtaining an improvement in the ocular condition at a
time when a therapeutic amount of the active agent is not present
at the ocular site, and; (d) maintaining the improvement in the
ocular condition for an extended period of time during which a
therapeutic amount of the active agent is not present at the ocular
site.
19. A method for treating an inflammatory posterior ocular
condition, the method comprising the steps of: (a) inserting a
biodegradable implant into a posterior ocular site of a patient
with an inflammatory posterior ocular condition, the biodegradable
implant comprising (i) an anti-inflammatory active agent mixed with
(ii) a biodegradable polymer; (b) releasing substantially all of
the anti-inflammatory active agent from the biodegradable implant;
(c) obtaining an improvement in the inflammatory posterior ocular
condition at a time when a therapeutic amount of the
anti-inflammatory active agent is not present at the posterior
ocular site, and; (d) maintaining the improvement in the
inflammatory ocular condition for an extended period of time during
which a therapeutic amount of the anti-inflammatory active agent is
not present at the posterior ocular site.
20. The method of claim 19, wherein the inserting step comprises
the step of placing the biodegradable implant into the vitreous
through the pars plana and placing the implant adjacent thereto in
the vitreous cavity.
21. A method for treating persistent macular edema, the method
comprising the steps of: (a) inserting a biodegradable implant deep
into the vitreous of a patient with persistent macular edema, the
biodegradable implant comprising (i) dexamethasone mixed with (ii)
a bioerodible PLGA co-polymer; (b) releasing all of the
dexamethasone from the biodegradable implant; (c) obtaining an
improvement in the persistent macular edema at a time when a
therapeutic amount of the dexamethasone is not present in the
vitreous, and; (d) maintaining the improvement in the persistent
macular edema for an extended period of time during which a
therapeutic amount of the dexamethasone is not present in the
vitreous.
22. The method of claim 21, wherein the inserting step comprises
the step of placing the biodegradable implant into the vitreous
about 2 mm to about 6 mm anterior of the macular
23. The method of claim 21, wherein the releasing step comprises
the step of releasing about 700 .mu.g of dexamethasone from the
biodegradable implant.
24. The method of claim 23, wherein the releasing step comprises
the step of releasing about 700 .mu.g of dexamethasone from the
biodegradable implant within about 30 days to 40 days after the
inserting step.
24. The method of claim 21, wherein the obtaining step comprises
obtaining an improvement in the visual acuity of the patient.
25. The method of claim 24, wherein the improvement in the visual
acuity of the patient is obtained within about 30 days to about 180
days after the inserting step.
26. The method of claim 25, wherein the maintaining step, by which
the improvement in the visual acuity of the patient with persistent
macular edema is maintained for an extended period of time during
which a therapeutic amount of the dexamethasone is not present in
the vitreous, is a period of time of about 30 days to about 150
days after the obtaining step.
27. A method for improving the visual acuity of a patient with
persistent macular edema, the method comprising the steps of: (a)
inserting a biodegradable implant into the vitreous of a patient
with persistent macular edema by placing the biodegradable implant
about 2 mm to about 6 mm anterior of the macular, the biodegradable
implant comprising (i) about 700 .mu.g dexamethasone mixed with
(ii) a bioerodible PLGA co-polymer; (b) releasing the 700 .mu.g of
dexamethasone from the biodegradable implant within about 30 days
to about 40 days after the inserting step; (c) obtaining an
improvement in the visual acuity of the patient with the persistent
macular edema at a time within about 30 days and 180 days after the
inserting step during which time a therapeutic amount of the
dexamethasone is not present in the vitreous, and; (d) maintaining
the improvement in the visual acuity of the patient with the
persistent macular edema for about 30 days to about 150 days after
the obtaining step during a time a therapeutic amount of the
dexamethasone is not present in the vitreous.
28. A method for treating an ocular condition, the method
comprising the steps of: (a) inserting an implant into the vitreous
cavity of a patient with an ocular condition, the implant
comprising (i) a steroid, and (ii) a carrier associated with the
steroid; (b) releasing substantially all of the steroid from the
implant, and; (c) obtaining an improvement in the ocular condition
with no increase in intraocular pressure above about 25 mm Hg.
29. A method for treating an ocular condition, the method
comprising the steps of: (a) inserting an implant into the vitreous
cavity of a patient with an ocular condition, the implant
comprising (i) a steroid, and (ii) a carrier associated with the
steroid; (b) releasing substantially all of the steroid from the
implant, and; (c) obtaining an improvement in the ocular condition
with no occurrence of an ocular cataract in the patient.
Description
[0001] This application is a Divisional of co-pending application
Ser. No. 10/837,357 filed on Apr. 30, 2004, and for which priority
is claimed under 35 U.S.C. .sctn. 120, the entire contents of which
are hereby incorporated by reference.
BACKGROUND
[0002] This invention relates to methods for extended treatment of
an ocular condition. In particular the present invention releases
to methods for extended treatment of an ocular condition with an
intraocular implant.
[0003] An ocular condition can include an inflammatory, neoplastic,
infectious, vascular, neovascular and/or degenerative disease,
aliment or condition which affects or involves the eye or one of
the parts or regions of the eye. Broadly speaking the eye includes
the eyeball and the tissues and fluids which constitute the
eyeball, the periocular muscles (such as the oblique and rectus
muscles) and the portion of the optic nerve which is within or
adjacent to the eyeball. An anterior ocular condition is a disease,
ailment or condition which affects or which involves an anterior
(i.e. front of the eye) ocular region, location or site (hereafter
an ocular site), such as a periocular muscle, an eye lid or an eye
ball tissue or fluid which is located anterior to the posterior
wall of the lens capsule or ciliary muscles. Thus, an anterior
ocular condition primarily affects or involves, the conjunctiva,
the cornea, the anterior chamber, the iris, the posterior chamber
(behind the iris but in front of the posterior wall of the lens
capsule), the lens or the lens capsule and blood vessels and nerve
which vascularize or innervate an anterior ocular region or site. A
posterior ocular condition is a disease, ailment or condition which
primarily affects or involves a posterior ocular site such as
choroid or sclera (in a position posterior to a plane through the
posterior wall of the lens capsule), vitreous, vitreous chamber,
retina, optic nerve (including the optic disc), and blood vessels
and nerves which vascularize or innervate a posterior ocular
site.
[0004] Thus, a posterior ocular condition can include a disease,
ailment or condition, such as for example, macular degeneration
(such as non-exudative age related macular degeneration and
exudative age related macular degeneration); macular hole; light,
radiation or thermal damage to a posterior ocular tissue; choroidal
neovascularization; acute macular neuroretinopathy; macular edema
(such as cystoid macular edema and diabetic macular edema);
Behcet's disease, retinal disorders, diabetic retinopathy
(including proliferative diabetic retinopathy); retinal arterial
occlusive disease; central retinal vein occlusion; uveitic retinal
disease; retinal detachment; ocular trauma which affects a
posterior ocular site; a posterior ocular condition caused by or
influenced by an ocular laser treatment; posterior ocular
conditions caused by or influenced by a photodynamic therapy;
photocoagulation; radiation retinopathy; epiretinal membrane
disorders; branch retinal vein occlusion; anterior ischemic optic
neuropathy; non-retinopathy diabetic retinal dysfunction, retinitis
pigmentosa and glaucoma. Glaucoma can be considered a posterior
ocular condition because the therapeutic goal is to prevent the
loss of or reduce the occurrence of loss of vision due to damage to
or loss of retinal cells or retinal ganglion cells (i.e.
neuroprotection).
[0005] An anterior ocular condition can include a disease, ailment
or condition, such as for example, aphakia; pseudophakia;
astigmatism; blepharospasm; cataract; conjunctival diseases;
conjunctivitis; corneal diseases; corneal ulcer; dry eye syndromes;
eyelid diseases; lacrimal apparatus diseases; lacrimal duct
obstruction; myopia; presbyopia; hyperopia; pupil disorders;
refractive disorders and strabismus. Glaucoma can also be
considered to be an anterior ocular condition because a clinical
goal of glaucoma treatment can be to reduce a hypertension of
aqueous fluid in the anterior chamber of the eye (i.e. reduce
intraocular pressure).
[0006] The present invention is directed to a method for providing
an extended treatment of an ocular condition, such as an anterior
ocular condition or a posterior ocular condition or to an ocular
condition which can be characterized as both an anterior ocular
condition and a posterior ocular condition.
[0007] Therapeutic compounds useful for the treatment of an ocular
condition can include cytokines and active agents with, for
example, an anti-neoplastic (i.e. anti-cancer), anti-angiogenesis,
kinase inhibition, anticholinergic, anti-adrenergic and/or
anti-inflammatory activity.
[0008] Macular degeneration, such as age related macular
degeneration ("AMD") is a leading cause of irreversible vision loss
in elderly populations. It is estimated that thirteen million
Americans have evidence of macular degeneration. Macular
degeneration results in a break down or injury to the macula, the
central part of the retina responsible for the sharp, direct vision
needed to read or drive. Central vision is especially or
selectively affected. Macular degeneration is diagnosed as either
dry or wet (exudative). The dry form of macular degeneration is
more common than the wet form of macular degeneration, with about
90% of AMD patients being diagnosed with dry AMD. The wet form of
the disease usually leads to more rapid and more serious vision
loss. Macular degeneration can produce a slow or sudden painless
loss of vision. The cause of macular degeneration is not clear. The
dry form of AMD may result in thinning of macular tissues,
depositing of pigment in the macula, or a combination of the two
processes. With wet AMD, new blood vessels grow within and beneath
the retina and leak blood and fluid. This leakage causes injury to
retinal cells and creates blind spots in central vision.
[0009] Macular edema (ME) can result in a swelling or thickening of
the macular and appears to be a nonspecific response of the retina
to a variety of insults. Thus, ME is associated with a number of
diseases, including anterior or posterior uveitis, retinal vascular
abnormalities (diabetic retinopathy and retinal venous occlusive
disease), as a sequela of cataract surgery (Irvine-Gass Syndrome),
macular degeneration, vitreo-macular traction syndrome, inherited
or acquired retinal degeneration, eye inflammation, idiopathic
central serous chorioretinopathy, pars planitis, retinitis
pigmentosa, radiation retinopathy, posterior vitreous detachment,
epiretinal membrane formation, idiopathic juxtafoveal retinal
telangiectasia, following Nd:YAG capsulotomy or iridotomy. Some
patients with ME may have a history of use of topical epinephrine
or prostaglandin analogs for glaucoma. Macular edema involves the
development of microangiopathy, characterized by abnormal retinal
vessel permeability and capillary leakage into the adjacent retinal
tissues. The macula becomes thickened due to accumulation of fluid
which leaks out of weak blood vessel walls due to a breakdown of
the inner blood-retinal barrier at the level of the capillary
endothelium, often resulting in significant disturbances in visual
acuity. The blood and fluid leaks out of the weak vessel walls into
a very small area of the macula which is rich in cones, the
photoreceptors that detect color and from which daytime vision
depends. Blurring then occurs in the middle or just to the side of
the central visual field. Visual loss can progress over a period of
years. Symptoms of ME include blurred central vision, distorted
vision, vision tinted pink and light sensitivity.
[0010] In some cases macular edema can resolves spontaneously or
with show remission after a short-term treatment. However, in cases
of persistent macular edema (PME), visual loss continues to be a
significant therapeutic challenge. Therapies for macular edema
utilize a stepwise approach including surgical and medical methods.
A first line of treatment for certain types of ME can be
anti-inflammatory drops topically applied. Currently there are no
approved therapies for the treatment of PME. Macular edema that has
failed to respond to drug therapy and laser photocoagulation
represents a significant unmet medical need.
[0011] Drug therapy for macular edema can include topical,
periocular, subconjunctival/intravitreal, or systemic
corticosteroids; topical and systemic nonsteroidal
anti-inflammatory agents (NSAIDs); and/or immunosuppressants.
Nonetheless, with variable incidence, macular edema can persist
regardless of treatment or causation resulting in severe vision
loss. Liquid, intravitreal triamcinolone acetonide (available from
Bristol Myers Squibb under the tradename Kenalog-40.RTM.) injection
has been used to treat ocular inflammation and macula edema.
Kenalog-40.RTM. is a suspension triamcinolone acetonide (40 mg/mL)
formulated with sodium chloride for isotonicity, 0.9% (w/v) benzyl
alcohol as preservative, 0.75% carboxymethylcellulose sodium, and
0.04%, polysorbate 80. It is approved for intramuscular depot
delivery for the treatment of inflammation and has been used
intravitreally to treat ocular inflammation as well as macular
edema due to numerous causes. Unfortunately, side-effects including
elevated intraocular pressure, cataract, endophthalmitis (such as
infectious endophthalmitis and sterile endophthalmitis), retinal
toxicity and crystalline retinal deposits have been reported from
clinical use of intravitreal triamcinolone acetonide.
[0012] Surgical methods for the treatment of macular edema
including laser photocoagulation have had mixed results. Focal/grid
laser photocoagulation for the prevention of moderate visual loss
has been shown to be efficacious in diabetic retinopathy and branch
retinal vein occlusion patients, but not in central retinal vein
occlusion patients. As a last resort, a vitrectomy is sometimes
performed in patients who have persistent macular edema that has
failed to respond to less invasive treatments.
[0013] Dexamethasone, a potent anti-inflammatory in the
corticosteroid family, has been shown to suppress inflammation by
inhibiting edema, fibrin deposition, capillary deposition and
phagocytic migration of the inflammatory response. Corticosteroids
prevent the release of prostaglandins which have been identified as
one of the causative agents of cystoid macular edema. Additionally,
corticosteroids including dexamethasone have also been shown to
have potent anti-permeability activity by inhibiting the synthesis
of VEGF. Despite known anti-inflammatory and anti-permeability
properties, use of corticosteroid in the treatment of macular edema
has been limited because of the inability to deliver and to
maintain adequate quantities of the drugs at the macular without
resultant toxicities.
[0014] Previously, dexamethasone use has yielded varying degrees of
success in treating retinal disorders including macular edema
largely due to the inability to deliver and maintain adequate
quantities of the drug to the posterior segment (vitreous) without
resultant toxicities. Topical administration of 1 drop (50 .mu.l)
of a 0.1% dexamethasone ophthalmic suspension, 4 times a day is
equivalent to approximately 200 .mu.g per day, however, only about
1% (2 .mu.g per day) reaches the anterior segment, and only a
fraction of that amount moves into the posterior segment
(vitreous). Although intravitreal injections of dexamethasone have
been used, the exposure of the drug is very temporal as the
half-life of the drug within the eye is approximately 3 hours.
Periocular and posterior sub-Tenon's injections of dexamethasone
have been used, but with only short-term treatment effect.
[0015] Treatment with corticosteroids must be monitored closely due
to potential toxicity and long-term side effects. Adverse reactions
listed for conventional ophthalmic dexamethasone preparations
include: glaucoma (with optic nerve damage, visual acuity and field
defects), posterior subcapsular cataract formation, and secondary
ocular infection from pathogens including herpes simplex. Systemic
doses of dexamethasone can be as high as 9000 .mu.g/kg/day, of
which only a small portion reaches the posterior segment, and may
be associated with additional hazardous side-effects including
hypertension, hyperglycemia, increased susceptibility to infection,
and peptic ulcers.
[0016] Although an efficient means of delivering a drug to the
posterior segment is direct delivery into the vitreous body, the
natural pharmacokinetics of the eye typically result in a short
half-life unless the drug can be delivered using a formulation
capable of providing sustained release. By delivering a drug
intravitreally, the blood-eye barrier is circumvented and
intraocular therapeutic levels can be achieved without the risk of
systemic toxicity.
[0017] An anti-inflammatory (i.e. immunosuppressive) agent can be
used for the treatment of an ocular condition which involves
inflammation, such as an uveitis or macula edema. Thus, topical or
oral glucocorticoids have been used to treat uveitis. A major
problem with topical and oral drug administration is the inability
of the drug to achieve an adequate (i.e. therapeutic) intraocular
concentration. See e.g. Bloch-Michel E. (1992). Opening address:
intermediate uveitis, In Intermediate Uveitis, Dev. Opthalmol, W.
R. F. Boke et al. editors., Basel: Karger, 23:1-2; Pinar, V., et
al. (1997). Intraocular inflammation and uveitis" In Basic and
Clinical Science Course. Section 9 (1997-1998) San Francisco
American Academy of Opthalmology, pp. 57-80, 102-103, 152-156;
Boke, W. (1992). Clinical picture of intermediate uveitis, In
Intermediate Uveitis, Dev. Opthalmol. W. R. F. Boke et al.
editors., Basel: Karger, 23:20-7; and Cheng C-K et al. (1995).
Intravitreal sustained-release dexamethasone device in the
treatment of experimental uveitis, Invest. Opthalmol. Vis. Sci.
36:442-53.
[0018] Systemic glucocorticoid administration can be used alone or
in addition to topical glucocorticoids for the treatment of
uveitis. However, prolonged exposure to high plasma concentrations
(administration of prednisone 1 mg/kg/day for 2-3 weeks) of steroid
is often necessary so that therapeutic levels can be achieved in
the eye.
[0019] Unfortunately, these high drug plasma levels commonly lead
to systemic side effects such as hypertension, hyperglycemia,
increased susceptibility to infection, peptic ulcers, psychosis,
and other complications. Cheng C-K et al. (1995). Intravitreal
sustained-release dexamethasone device in the treatment of
experimental uveitis, Invest. Opthalmol. Vis. Sci. 36:442-53;
Schwartz, B. (1966). The response of ocular pressure to
corticosteroids, Opthalmol. Clin. North Am. 6:929-89; Skalka, H. W.
et al. (1980). Effect of corticosteroids on cataract formation,
Arch Opthalmol 98:1773-7; and Renfro, L. et al. (1992). Ocular
effects of topical and systemic steroids, Dermatologic Clinics
10:505-12.
[0020] Additionally, delivery to the eye of a therapeutic amount of
an active agent can be difficult, if not impossible, for drugs with
short plasma half-lives since the exposure of the drug to
intraocular tissues is limited. Therefore, a more efficient way of
delivering a drug to treat a posterior ocular condition is to place
the drug directly in the eye, such as directly into the vitreous.
Maurice, D. M. (1983). Micropharmaceutics of the eye, Ocular
Inflammation Ther. 1:97-102; Lee, V. H. L. et al. (1989). Drug
delivery to the posterior segment" Chapter 25 In Retina. T. E.
Ogden and A. P. Schachat eds., St. Louis: CV Mosby, Vol. 1, pp.
483-98; and Olsen, T. W. et al. (1995). Human scleral permeability:
effects of age, cryotherapy, transscleral diode laser, and surgical
thinning, Invest. Opthalmol. Vis. Sci. 36:1893-1903.
[0021] Techniques such as intravitreal injection of a drug have
shown promising results, but due to the short intraocular half-life
of active agent, such as the glucocorticoid dexamethasone
(approximately 3 hours), intravitreal injections must be frequently
repeated to maintain a therapeutic drug level. In turn, this
repetitive process increases the potential for side effects such as
retinal detachment, endophthalmitis, and cataracts. Maurice, D. M.
(1983). Micropharmaceutics of the eye, Ocular Inflammation Ther.
1:97-102; Olsen, T. W. et al. (1995). Human scleral permeability:
effects of age, cryotherapy, transscleral diode laser, and surgical
thinning, Invest. Opthalmol. Vis. Sci. 36:1893-1903; and Kwak, H.
W. and D'Amico, D. J. (1992). Evaluation of the retinal toxicity
and pharmacokinetics of dexamethasone after intravitreal injection,
Arch. Opthalmol. 110:259-66.
[0022] Additionally, topical, systemic, and periocular
glucocorticoid treatment must be monitored closely due to toxicity
and the long-term side effects associated with chronic systemic
drug exposure sequelae. Rao, N. A. et al. (1997). Intraocular
inflammation and uveitis, In Basic and Clinical Science Course.
Section 9 (1997-1998) San Francisco: American Academy of
Opthalmology, pp. 57-80, 102-103, 152-156; Schwartz, B. (1966). The
response of ocular pressure to corticosteroids, Opthalmol Clin
North Am 6:929-89; Skalka, H. W. and Pichal, J. T. (1980). Effect
of corticosteroids on cataract formation, Arch Opthalmol 98:1773-7;
Renfro, L and Snow, J. S. (1992). Ocular effects of topical and
systemic steroids, Dermatologic Clinics 10:505-12; Bodor, N. et al.
(1992). A comparison of intraocular pressure elevating activity of
loteprednol etabonate and dexamethasone in rabbits, Current Eye
Research 11:525-30.
[0023] U.S. Pat. No. 6,217,895 discusses a method of administering
a corticosteroid to the posterior segment of the eye, but does not
disclose a bioerodible implant.
[0024] U.S. Pat. No. 5,501,856 discloses controlled release
pharmaceutical preparations for intraocular implants to be applied
to the interior of the eye after a surgical operation for disorders
in retina/vitreous body or for glaucoma.
[0025] U.S. Pat. No. 5,869,079 discloses combinations of
hydrophilic and hydrophobic entities in a biodegradable sustained
release implant, and describes a polylactic acid polyglycolic acid
(PLGA) copolymer implant comprising dexamethasone. As shown by in
vitro testing of the drug release kinetics, the 100-120 .mu.g 50/50
PLGA/dexamethasone implant disclosed did not show appreciable drug
release until the beginning of the fourth week, unless a release
enhancer, such as HPMC was added to the formulation.
[0026] U.S. Pat. No. 5,824,072 discloses implants for introduction
into a suprachoroidal space or an avascular region of the eye, and
describes a methylcellulose (i.e. non-biodegradable) implant
comprising dexamethasone. WO 9513765 discloses implants comprising
active agents for introduction into a suprachoroidal or an
avascular region of an eye for therapeutic purposes.
[0027] U.S. Pat. Nos. 4,997,652 and 5,164,188 disclose
biodegradable ocular implants comprising microencapsulated drugs,
and describes implanting microcapsules comprising hydrocortisone
succinate into the posterior segment of the eye.
[0028] U.S. Pat. No. 5,164,188 discloses encapsulated agents for
introduction into the suprachoroid of the eye, and describes
placing microcapsules and plaques comprising hydrocortisone into
the pars plana. U.S. Pat. Nos. 5,443,505 and 5,766,242 disclose
implants comprising active agents for introduction into a
suprachoroidal space or an avascular region of the eye, and
describes placing microcapsules and plaques comprising
hydrocortisone into the pars plana.
[0029] Zhou et al. disclose a multiple-drug implant comprising
5-fluorouridine, triamcinolone, and human recombinant tissue
plasminogen activator for intraocular management of proliferative
vitreoretinopathy (PVR). Zhou, T, et al. (1998). Development of a
multiple-drug delivery implant for intraocular management of
proliferative vitreoretinopathy, Journal of Controlled Release 55:
281-295.
[0030] U.S. Pat. No. 6,046,187 discusses methods and compositions
for modulating local anesthetic by administering one or more
glucocorticosteroid agents before, simultaneously with or after the
administration of a local anesthetic at a site in a patient.
[0031] U.S. Pat. No. 3,986,510 discusses ocular inserts having one
or more inner reservoirs of a drug formulation confined within a
bioerodible drug release rate controlling material of a shape
adapted for insertion and retention in the "sac of the eye," which
is indicated as being bounded by the surfaces of the bulbar
conjunctiva of the sclera of the eyeball and the palpebral
conjunctiva of the eyelid, or for placement over the corneal
section of the eye.
[0032] U.S. Pat. No. 6,369,116 discusses an implant with a release
modifier inserted within a scleral flap.
[0033] EP 0 654256 discusses use of a scleral plug after surgery on
a vitreous body, for plugging an incision.
[0034] U.S. Pat. No. 4,863,457 discusses the use of a bioerodible
implant to prevent failure of glaucoma filtration surgery by
positioning the implant either in the subconjunctival region
between the conjunctival membrane overlying it and the sclera
beneath it or within the sclera itself within a partial thickness
sclera flap.
[0035] EP 488 401 discusses intraocular implants, made of certain
polylactic acids, to be applied to the interior of the eye after a
surgical operation for disorders of the retina/vitreous body or for
glaucoma.
[0036] EP 430539 discusses use of a bioerodible implant which is
inserted in the suprachoroid.
[0037] Significantly, it is known that PLGA co-polymer formulations
of a bioerodible polymer comprising an active agent typically
release the active agent with a characteristic sigmoidal release
profile (as viewed as time vs percent of total active agent
released), that is after a relatively long initial lag period (the
first release phase) when little if any active agent is released,
there is a high positive slope period when most of the active agent
is released (the second release phase) followed by another near
horizontal (third) release phase, when the drug release reaches a
plateau.
[0038] Thus, there is a need for a extended therapeutic treatment
of an ocular condition, such as posterior ocular condition. In
particular, there is a need for treatment over an extended
duration, for example, time periods extending up to 60 days, 90
days, 120 days, 6 months, 8 months, 12 months or more, after
release of a therapeutic amount of a drug at an ocular site, such
as the vitreous. Such extended treatment with an active agent can
be advantageous to prevent recurrence of the inflammatory or other
posterior ocular condition treated. It can also minimize the number
of surgical interventions required by the patient over time to
treat an ocular condition.
SUMMARY
[0039] The present invention meets these and other needs and
provides for methods and implants which can provide an extended
treatment of an ocular condition after release of a therapeutic
amount of a drug from an implant placed in the vitreous and with
maintenance of such a therapeutic effect for an extended period
during which a therapeutic level or amount of the drug is not
present is not detectable in the vitreous.
DEFINITIONS
[0040] The following terms as used herein have the following
meanings:
[0041] "About" means approximately or nearly and in the context of
a numerical value or range set forth herein means .+-.10% of the
numerical value or range recited or claimed.
[0042] "Active agent" and "drug" are used interchangeably and refer
to any substance used to treat an ocular condition.
[0043] "Anterior ocular condition" means a disease, ailment or
condition which affects or which involves an anterior (i.e. front
of the eye) ocular site, such as a periocular muscle, an eye lid or
an eye ball tissue or fluid which is located anterior to the
posterior wall of the lens capsule or ciliary muscles. Thus, an
anterior ocular condition primarily affects or involves, the
conjunctiva, the cornea, the conjunctiva, the anterior chamber, the
iris, the posterior chamber (behind the iris but in front of the
posterior wall of the lens capsule), the lens or the lens capsule
and blood vessels and nerve which vascularize or innervate an
anterior ocular region or site.
[0044] "Bioerodible polymer" means a polymer which degrades in
vivo, and wherein erosion of the polymer over time is required to
release the active agent. The words "bioerodible" and
"biodegradable" are synonymous and are used interchangeably
herein.
[0045] "Extended" as in "extended therapeutic effect" means for a
period of time greater than thirty days after release of all or all
substantially all of an active agent in vivo from an intraocular
implant. More preferably the extended therapeutic effect persists
for at least 60 days after release of all or all substantially all
of an active agent in vivo from an intraocular implant.
[0046] "Glaucoma" means primary, secondary and/or congenital
glaucoma. Primary glaucoma can include open angle and closed angle
glaucoma. Secondary glaucoma can occur as a complication of a
variety of other conditions, such as injury, inflammation, vascular
disease and diabetes.
[0047] "Inflammation-mediated" in relation to an ocular condition
means any condition of the eye which can benefit or potentially
benefit from treatment with an anti-inflammatory agent, and is
meant to include, but is not limited to, uveitis, macular edema,
acute macular degeneration, retinal detachment, ocular tumors,
fungal or viral infections, multifocal choroiditis, diabetic
uveitis, proliferative vitreoretinopathy (PVR), sympathetic
opthalmia, Vogt Koyanagi-Harada (VKH) syndrome, histoplasmosis, and
uveal effusion.
[0048] "Injury" or "damage" are interchangeable and refer to the
cellular and morphological manifestations and symptoms resulting
from an inflammatory-mediated condition, such as, for example,
inflammation.
[0049] "Measured under infinite sink conditions in vitro," means
assays to measure drug release in vitro, wherein the experiment is
designed such that the drug concentration in the receptor medium
never exceeds 5% of saturation. Examples of suitable assays may be
found, for example, in USP 23; NF 18 (1995) pp. 1790-1798.
[0050] "Ocular condition" means a disease, aliment or condition
which affects or involves the eye or one or the parts or regions of
the eye, such as a retinal disease. The eye includes the eyeball
and the tissues and fluids which constitute the eyeball, the
periocular muscles (such as the oblique and rectus muscles) and the
portion of the optic nerve which is within or adjacent to the
eyeball.
[0051] "Posterior ocular condition" means a disease, ailment or
condition which affects or involves a posterior ocular region or
site such as choroid or sclera (in a position posterior to a plane
through the posterior wall of the lens capsule), vitreous, vitreous
chamber, retina, optic nerve (including the optic disc), and blood
vessels and nerve which vascularize or innervate a posterior ocular
region or site.
[0052] "Steroidal anti-inflammatory agent" and "glucocorticoid" are
used interchangeably herein, and are meant to include steroidal
agents, compounds or drugs which reduce inflammation when
administered at a therapeutically effective level.
[0053] "Substantially" means at least 51%. A release of
substantially all of an active agent occurs when, at least 24 hours
after in vivo insertion of an intraocular implant, a therapeutic
amount of the active agent is not present in the vitreous. A
release of essentially all of an active agent is deemed to occur
when, at least 24 hours after in vivo insertion of an intraocular
implant, a detectable amount of the active agent is not present in
the vitreous. "Substantially" in relation to the blending, mixing
or dispersing of an active agent in a polymer, as in the phrase
"substantially homogenously dispersed" means that there are no or
essentially no particles (i.e. aggregations) of active agent in
such a homogenous dispersal.
[0054] "Suitable for insertion (or implantation) in (or into) an
ocular region or site" with regard to an implant, means an implant
which has a size (dimensions) such that it can be inserted or
implanted without causing excessive tissue damage and without
unduly physically interfering with the existing vision of the
patient into which the implant is implanted or inserted.
[0055] A method according to the present invention can be carried
out using an implant suitable for insertion, placement or
implantation at an ocular site, such as the vitreous. Suitable
implant can be made using the methods and materials set forth in
U.S. patent application Ser. No. 10/340,237.
[0056] The present invention encompasses a method for treating an
ocular condition. The method can have the steps of firstly
inserting an implant into an ocular site of a patient with an
ocular condition. The implant can be made of an active agent, and a
carrier associated with the active agent. The carrier can be a
polymer or a bioceramic material. The carried can be associated
with the active agent by mixing the active agent and the carrier,
dispersing the active agent in the carrier, encapsulating the
active agent by the carrier, incorporating the active agent within
the carrier, and the like.
[0057] The next (second) step in the method can be releasing
substantially all of the active agent from the implant. The third
step in the method can be obtaining an improvement in the ocular
condition at a time when a therapeutic amount of the active agent
is not present at the ocular site. A fourth step in the method can
be maintaining the improvement in the ocular condition for an
extended period of time during which a therapeutic amount of the
active agent is not present at the ocular site.
[0058] The releasing (second) step can occur over a first period of
time X, and the subsequent extended period of time during which an
improvement in the ocular condition is maintained, although a
therapeutic amount of the active agent is not present at the ocular
site, is a second period of time between 0.5.times. and 100.times..
The first period of time can be between about 30 days and about 40
days, such as about 35 days. The second period of time can be
between about 30 days and about 180 days.
[0059] The active agent can be an anti-inflammatory agent and the
carrier can be a bioerodible polymer. The implant can have a weight
between about 1 .mu.g and about 100 mg. The implant can have no
dimension less than about 0.1 mm and no dimension greater than
about 20 mm. The implant can have a volume of from about 1 mm.sup.3
to about 100 mm.sup.3, but preferably the implant has a volume of
between about 5-20 mm.sup.3
[0060] The improvement of the ocular condition obtained by a method
within the scope of the present invention can be determined by
observing an improved visual acuity, by observing an improved
visual contrast sensitivity, by observing a decreased retinal or
choroidal blood vessel leakage, by observing a decreased retinal or
macular thickness, or by observing a reduced number of cells in the
aqueous or vitreous humor or by determining a reduced flare.
[0061] The improvement in the ocular condition can occur at a time
when a detectable amount of the active agent is not present at the
ocular site. The ocular site can be vitreous and the active agent
can be dexamethasone.
[0062] Another method within the scope of the present invention is
a method for treating a chronic ocular condition by (a) inserting
an implant into an ocular site of a patient with an ocular
condition, the implant comprising (i) an active agent, and (ii) a
carrier associated with the active agent; (b) releasing
substantially all of the active agent from the implant; (c)
obtaining an improvement in the ocular condition at a time when a
therapeutic amount of the active agent is not present at the ocular
site, and; (d) maintaining the improvement in the ocular condition
for an extended period of time during which a therapeutic amount of
the active agent is not present at the ocular site.
[0063] A further method within the scope of the present invention
is a method for treating an inflammatory posterior ocular condition
by (a) inserting a biodegradable implant into a posterior ocular
site of a patient with an inflammatory posterior ocular condition,
the biodegradable implant comprising (i) an anti-inflammatory
active agent mixed with (ii) a biodegradable polymer; (b) releasing
substantially all of the anti-inflammatory active agent from the
biodegradable implant; (c) obtaining an improvement in the
inflammatory posterior ocular condition at a time when a
therapeutic amount of the anti-inflammatory active agent is not
present at the posterior ocular site, and; (d) maintaining the
improvement in the inflammatory ocular condition for an extended
period of time during which a therapeutic amount of the
anti-inflammatory active agent is not present at the posterior
ocular site. The inserting step is preferably carried out by
insertion of the implant through the pars plana and adjacent
thereto in the vitreous cavity. Alternately, the insertion step can
be carried out by placing the biodegradable implant into the
vitreous about 2 mm to about 6 mm anterior of the macular and not
along the visual axis of incoming light through the pupil
[0064] A detailed method within the scope of the present invention
is a method for treating persistent macular edema (a) inserting a
biodegradable implant deep into the vitreous of a patient with
persistent macular edema, the biodegradable implant comprising (i)
dexamethasone mixed with (ii) a bioerodible PLGA co-polymer; (b)
releasing all of the dexamethasone from the biodegradable implant;
(c) obtaining an improvement in the persistent macular edema at a
time when a therapeutic amount of the dexamethasone is not present
in the vitreous, and; (d) maintaining the improvement in the
persistent macular edema for an extended period of time during
which a therapeutic amount of the dexamethasone is not present in
the vitreous. The inserting step is preferably carried out by
insertion of the implant through the pars plana and adjacent
thereto in the vitreous cavity. Alternately, the insertion step can
be carried out by placing the biodegradable implant into the
vitreous about 2 mm to about 6 mm anterior of the macular and not
along the visual axis of incoming light through the pupil. The
releasing step can comprise releasing between about 350 700 .mu.g
of dexamethasone from the biodegradable implant. Additionally, the
releasing step can entail releasing about 700 .mu.g of
dexamethasone from the biodegradable implant within about 30 days
to 40 days after the inserting step. Notably, the obtaining step
can comprise obtaining an improvement in the visual acuity of the
patient. The improvement in the visual acuity of the patient can be
obtained within about 30 days to about 180 days after the inserting
step. Significantly, the maintaining step, by which the improvement
in the visual acuity of the patient with persistent macular edema
can be maintained for an extended period of time during which a
therapeutic amount of the dexamethasone is not present in the
vitreous, is a period of time of about 30 days to about 150 days
after the obtaining step.
[0065] A preferred method within the scope of the present invention
is a method for improving the visual acuity of a patient with
persistent macular edema by (a) inserting a biodegradable implant
into the vitreous of a patient with persistent macular edema by
inserting the biodegradable implant through the pars plana and
adjacent thereto in the vitreous cavity or alternately, the
insertion step can be carried out by placing the biodegradable
implant into the vitreous about 2 mm to about 6 mm anterior of the
macular and not along the visual axis of incoming light through the
pupil, the biodegradable implant comprising (i) about 350-700 .mu.g
dexamethasone mixed with (ii) a bioerodible PLGA co-polymer; (b)
releasing the 350-700 .mu.g of dexamethasone from the biodegradable
implant within about 30 days to about 40 days after the inserting
step; (c) obtaining an improvement in the visual acuity of the
patient with the persistent macular edema at a time within about 30
days and 180 days after the inserting step during which time when a
therapeutic amount of the dexamethasone is not present in the
vitreous, and; (d) maintaining the improvement in the visual acuity
of the patient with the persistent macular edema for about 30 days
to about 150 days after the obtaining step during a time when a
therapeutic amount of the dexamethasone is not present in the
vitreous.
[0066] The present invention also includes a method for treating an
ocular condition by inserting an implant into the vitreous cavity
of a patient with an ocular condition, the implant comprising (i) a
steroid, and (ii) a carrier associated with the steroid; followed
by releasing substantially all of the steroid from the implant, and
then obtaining an improvement in the ocular condition with no
increase in intraocular pressure in the patient above about 25 mm
Hg, where the patient had a baseline (i.e. prior to implant
insertion) IOP of less or equal to about 25 mm Hg.
[0067] The present invention also includes a method for treating an
ocular condition by inserting an implant into the vitreous cavity
of a patient with an ocular condition, the implant comprising (i) a
steroid, and (ii) a carrier associated with the steroid; followed
by releasing substantially all of the steroid from the implant, and
then obtaining an improvement in the ocular condition with no
occurrence of an ocular cataract in the patient subsequent to
insertion of the implant.
DRAWINGS
[0068] FIG. 1 is a graph showing vitreous humor concentrations
(ng/ml) of dexamethasone over a period of 72 hours for two
tabletted implants (350 .mu.g or 700 .mu.g of dexamethasone) and
for two extrusion formed implants (350 .mu.g or 700 .mu.g of
dexamethasone)
[0069] FIG. 2 is a graph showing cumulative percent of
dexamethasone released into the vitreous humor over a period of 72
hours for two tabletted implants (350 .mu.g or 700 .mu.g of
dexamethasone) and for two extrusion formed implants (350 .mu.g or
700 .mu.g of dexamethasone)
[0070] FIG. 3 is a graph showing vitreous humor concentrations
(ng/ml) of dexamethasone over a period of 84 days for two tabletted
implants (350 .mu.g or 700 .mu.g of dexamethasone) and for two
extrusion formed implants (350 .mu.g or 700 .mu.g of
dexamethasone)
[0071] FIG. 4 is a graph showing cumulative percent of
dexamethasone released into the vitreous humor over a period of 84
days for two tabletted implants (350 .mu.g or 700 .mu.g of
dexamethasone) and for two extrusion formed implants (350 .mu.g or
700 .mu.g of dexamethasone.
[0072] FIG. 5 illustrates diagrammatically a cross-sectional view
of an eye.
DESCRIPTION
[0073] The present invention is based upon the discovery of methods
for obtaining and for maintaining a therapeutic treatment of an
ocular condition during a period of time during which a therapeutic
amount of an active agent is not present. A method within the scope
of the present invention can be carried out by inserting an implant
comprising an active agent into an ocular site of a patient. Over a
first period of time the implant then releases all of it's active
agent. There is then obtained an amelioration of a manifestation or
of a symptom of the ocular condition (i.e. a therapeutic effect)
for a second period of time during which a detectable or
therapeutic amount of the active agent is not present at the ocular
site.
[0074] It is generally accepted that treatment of a chronic ocular
condition requires chronic administration of a therapeutic amount
of a suitable active agent. Glaucoma is a chronic ocular condition
characterized by high (i.e. greater than 25 mm Hg) intra ocular
(aqueous humor) pressure. It is known that if a patient receiving
topical (i.e. applied as eye drops) anti-glaucoma medication stops
using the topical anti-glaucoma medication his intraocular pressure
("IOP") will quickly revert to its former (baseline) high
(unmedicated) intraocular pressure raise. The period for return to
baseline IOP is referred to as the washout period. Well before the
conclusion of the washout period (i.e. usually after a few hours or
at most a few days) of time there is no longer a therapeutic amount
or a detectable amount of the active agent in question present for
treatment of the ocular condition. Thus the term washout refers to
the time period required for return to substantially a baseline
(pre-therapeutic) condition, not to the time period required for
removal of the active agent. The washout period for topical
beta-blocker anti-glaucoma medication is about four weeks. The
washout period for topical sympathomimetics (stimulating alpha and
beta receptors; i.e. epinephrine) anti-glaucoma medication is about
three weeks. The washout period for topical miotics (i.e.
pilocarpine) anti-glaucoma medication is about 48 hours. Marcon,
I., A double-masked comparison of betaxolol and levobunolol for the
treatment of primary open-angle glaucoma, Arq Bras Oftalmol 1990;
53(1):27-32.
[0075] Additionally, it is known that the washout period for
topical carbonic anhydrase inhibitor (i.e. dorzolamide)
anti-glaucoma medication is two to four weeks, and that the washout
period for alpha adrenergic receptor agonists (i.e. brimonidine) is
also about two to four weeks. Molfino, F., et al., IOP-lowering
effect of dorzolamide 2% versus brimonidine tartrate 0.2%. A
prospective randomized cross over study, Invest Opthalmol V is Sci
1998 Mar. 15; 39(4):S481. The washout period for brimonidine may be
as long as five weeks and as long as eight weeks for a
prostaglandin (i.e. latanoprost) anti-glaucoma medication. Stewart,
W., et al., Washout periods for brimonidine 0.2% and latanoprost
0.005%, Am J Opthalmol 2001 June; 131(6):798-799.
[0076] To confirm and to supplement the existence of washout
periods, three different population of patients with glaucoma were
examined, as set forth by Example A, supra. The results set forth
by Example A show that within a short period of a day or two after
stopping chronic use of various anti-glaucoma medications, the mean
intraocular pressure of all patient populations increased
significantly, thereby showing that a chronic intraocular condition
requires chronic treatment to obtain an ongoing therapeutic
effect.
[0077] Thus, it was surprising and unexpected to discover that
methods within the scope of the present invention permit ongoing
therapeutic treatment of a chronic ocular condition for an extended
period of time after the washout period--when both a therapeutic
level of the active agent is (long since) no longer present and by
which time it was expected that a return or a substantial return to
a baseline condition (i.e. as assessed prior to commencement of
therapy) should have occurred in the patients. Specifically, prior
to the present invention it was thought that continuous and
prolonged therapy (i.e. chronic active agent [i.e. steroid]
administration) was required to treat a chronic ocular
condition.
[0078] The present invention thereby permits an ocular condition to
be treated with use of less active agent for a shorter duration
with fewer side effects and complications, as compared to a
treatment of the same ocular condition with the same active agent
administered as a non-implant formulation (i.e. as a liquid
intravitreal injection). Thus, the present invention permits a
short term treatment (i.e. release of an active agent from an
intra-vitreal implant over 10-40 days) to provide a long term
therapeutic benefit (i.e. for 150 days or longer after all the
active agent has been released from the implant) with fewer side
effects and fewer complications due to removal of the need for
chronic dosing. Thus a desired clinical (therapeutic) effect such
as lower IOP, less inflammation, decreased retinal thickness,
increased visual acuity, increased visual contract sensitivity,
reduced retinal and/or choriodal blood vessel leakage can be
obtained and maintained for an extended period of time (i.e. about
6 months or longer) after intra-vitreal release (i.e. after a
sustained release over 10-40 days) of all the active agent.
[0079] The present invention encompasses biodegradable ocular
implants and implant systems and methods of using such implants and
implant systems for treating posterior ocular conditions. The
implants can be formed to be monolithic, that is the active agent
is homogenously distributed or dispersed throughout the
biodegradable polymer matrix. Additionally, the implants can are
formed to release an active agent into an ocular region of the eye
over various time periods. Thus, the active agent can be released
from implants made according to the present invention for a period
of time of, for example, 30-40 days.
[0080] Biodegradable Implants for Treating an Ocular Condition
[0081] The implants of the present invention can include an active
agent mixed with or dispersed within a biodegradable polymer. The
implant compositions can vary according to the preferred drug
release profile, the particular active agent used, the ocular
condition being treated, and the medical history of the patient.
Active agents that may be used include, but are not limited to
(either by itself in an implant within the scope of the present
invention or in combination with another active agent):
ace-inhibitors, endogenous cytokines, agents that influence
basement membrane, agents that influence the growth of endothelial
cells, adrenergic agonists or blockers, cholinergic agonists or
blockers, aldose reductase inhibitors, analgesics, anesthetics,
antiallergics, anti-inflammatory agents, antihypertensives,
pressors, antibacterials, antivirals, antifungals, antiprotozoals,
anti-infectives, antitumor agents, antimetabolites, antiangiogenic
agents, tyrosine kinase inhibitors, antibiotics such as
aminoglycosides such as gentamycin, kanamycin, neomycin, and
vancomycin; amphenicols such as chloramphenicol; cephalosporins,
such as cefazolin HCl; penicillins such as ampicillin, penicillin,
carbenicillin, oxycillin, methicillin; lincosamides such as
lincomycin; polypeptide antibiotics such as polymixin and
bacitracin; tetracyclines such as tetracycline; quinolones such as
ciproflaxin, etc.; sulfonamides such as chloramine T; and sulfones
such as sulfanilic acid as the hydrophilic entity, anti-viral
drugs, e.g. acyclovir, gancyclovir, vidarabine, azidothymidine,
dideoxyinosine, dideoxycytosine, dexamethasone, ciproflaxin, water
soluble antibiotics, such as acyclovir, gancyclovir, vidarabine,
azidothymidine, dideoxyinosine, dideoxycytosine; epinephrine;
isoflurphate; adriamycin; bleomycin; mitomycin; ara-C; actinomycin
D; scopolamine; and the like, analgesics, such as codeine,
morphine, keterolac, naproxen, etc., an anesthetic, e.g. lidocaine;
.beta.-adrenergic blocker or .beta.-adrenergic agonist, e.g.
ephidrine, epinephrine, etc.; aldose reductase inhibitor, e.g.
epalrestat, ponalrestat, sorbinil, tolrestat; antiallergic, e.g.
cromolyn, beclomethasone, dexamethasone, and flunisolide;
colchicine, anihelminthic agents, e.g. ivermectin and suramin
sodium; antiamebic agents, e.g. chloroquine and chlortetracycline;
and antifungal agents, e.g. amphotericin, etc., anti-angiogenesis
compounds such as anecortave acetate, retinoids such as Tazarotene,
anti-glaucoma agents, such as brimonidine (Alphagan and Alphagan
P), acetozolamide, bimatoprost (Lumigan), Timolol, mebefunolol;
memantine; alpha-2 adrenergic receptor agonists; 2ME2;
anti-neoplastics, such as vinblastine, vincristine, interferons;
alpha., beta. and gamma., antimetabolites, such as folic acid
analogs, purine analogs, and pyrimidine analogs; immunosuppressants
such as azathiprine, cyclosporine and mizoribine; miotic agents,
such as carbachol, mydriatic agents such as atropine, etc.,
protease inhibitors such as aprotinin, camostat, gabexate,
vasodilators such as bradykinin, etc., and various growth factors,
such epidermal growth factor, basic fibroblast growth factor, nerve
growth factors, and the like.
[0082] In one variation the active agent is methotrexate. In
another variation, the active agent is a retinoic acid. In another
variation, the active agent is an anti-inflammatory agent such as a
nonsteroidal anti-inflammatory agent. Nonsteroidal
anti-inflammatory agents that may be used include, but are not
limited to, aspirin, diclofenac, flurbiprofen, ibuprofen,
ketorolac, naproxen, and suprofen. In a further variation, the
anti-inflammatory agent is a steroidal anti-inflammatory agent,
such as dexamethasone.
[0083] Steroidal Anti-Inflammatory Agents
[0084] The steroidal anti-inflammatory agents that may be used in
the ocular implants include, but are not limited to,
21-acetoxypregnenolone, alclometasone, algestone, amcinonide,
beclomethasone, betamethasone, budesonide, chloroprednisone,
clobetasol, clobetasone, clocortolone, cloprednol, corticosterone,
cortisone, cortivazol, deflazacort, desonide, desoximetasone,
dexamethasone, diflorasone, diflucortolone, difluprednate,
enoxolone, fluazacort, flucloronide, flumethasone, flunisolide,
fluocinolone acetonide, fluocinonide, fluocortin butyl,
fluocortolone, fluorometholone, fluperolone acetate, fluprednidene
acetate, fluprednisolone, flurandrenolide, fluticasone propionate,
formocortal, halcinonide, halobetasol propionate, halometasone,
halopredone acetate, hydrocortamate, hydrocortisone, loteprednol
etabonate, mazipredone, medrysone, meprednisone,
methylprednisolone, mometasone furoate, paramethasone,
prednicarbate, prednisolone, prednisolone 25-diethylamino-acetate,
prednisolone sodium phosphate, prednisone, prednival, prednylidene,
rimexolone, tixocortol, triamcinolone, triamcinolone acetonide,
triamcinolone benetonide, triamcinolone hexacetonide, and any of
their derivatives.
[0085] In one embodiment, cortisone, dexamethasone, fluocinolone,
hydrocortisone, methylprednisolone, prednisolone, prednisone, and
triamcinolone, and their derivatives, are preferred steroidal
anti-inflammatory agents. In another preferred variation, the
steroidal anti-inflammatory agent is dexamethasone. In another
variation, the biodegradable implant includes a combination of two
or more steroidal anti-inflammatory agents.
[0086] The active agent, such as a steroidal anti-inflammatory
agent, can comprise from about 10% to about 90% by weight of the
implant. In one variation, the agent is from about 40% to about 80%
by weight of the implant. In a preferred variation, the agent
comprises about 60% by weight of the implant. In a more preferred
embodiment of the present invention, the agent can comprise about
50% by weight of the implant.
[0087] Biodegradable Polymers
[0088] In one variation, the active agent can be homogeneously
dispersed in the biodegradable polymer of the implant. The implant
can be made, for example, by a sequential or double extrusion
method. The selection of the biodegradable polymer used can vary
with the desired release kinetics, patient tolerance, the nature of
the disease to be treated, and the like. Polymer characteristics
that are considered include, but are not limited to, the
biocompatibility and biodegradability at the site of implantation,
compatibility with the active agent of interest, and processing
temperatures. The biodegradable polymer matrix usually comprises at
least about 10, at least about 20, at least about 30, at least
about 40, at least about 50, at least about 60, at least about 70,
at least about 80, or at least about 90 weight percent of the
implant. In one variation, the biodegradable polymer matrix
comprises about 40% to 50% by weight of the implant.
[0089] Biodegradable polymers which can be used include, but are
not limited to, polymers made of monomers such as organic esters or
ethers, which when degraded result in physiologically acceptable
degradation products. Anhydrides, amides, orthoesters, or the like,
by themselves or in combination with other monomers, may also be
used. The polymers are generally condensation polymers. The
polymers can be crosslinked or non-crosslinked. If crosslinked,
they are usually not more than lightly crosslinked, and are less
than 5% crosslinked, usually less than 1% crosslinked.
[0090] For the most part, besides carbon and hydrogen, the polymers
will include oxygen and nitrogen, particularly oxygen. The oxygen
may be present as oxy, e.g., hydroxy or ether, carbonyl, e.g.,
non-oxo-carbonyl, such as carboxylic acid ester, and the like. The
nitrogen can be present as amide, cyano, and amino. An exemplary
list of biodegradable polymers that can be used are described in
Heller, Biodegradable Polymers in Controlled Drug Delivery, In:
"CRC Critical Reviews in Therapeutic Drug Carrier Systems", Vol. 1.
CRC Press, Boca Raton, Fla. (1987).
[0091] Of particular interest are polymers of hydroxyaliphatic
carboxylic acids, either homo- or copolymers, and polysaccharides.
Included among the polyesters of interest are homo- or copolymers
of D-lactic acid, L-lactic acid, racemic lactic acid, glycolic
acid, caprolactone, and combinations thereof. Copolymers of
glycolic and lactic acid are of particular interest, where the rate
of biodegradation is controlled by the ratio of glycolic to lactic
acid. The percent of each monomer in poly(lactic-co-glycolic)acid
(PLGA) copolymer may be 0-100%, about 15-85%, about 25-75%, or
about 35-65%. In certain variations, 25/75 PLGA and/or 50/50 PLGA
copolymers are used. In other variations, PLGA copolymers are used
in conjunction with polylactide polymers.
[0092] Biodegradable polymer matrices that include mixtures of
hydrophilic and hydrophobic ended PLGA may also be employed, and
are useful in modulating polymer matrix degradation rates.
Hydrophobic ended (also referred to as capped or end-capped) PLGA
has an ester linkage hydrophobic in nature at the polymer terminus.
Typical hydrophobic end groups include, but are not limited to
alkyl esters and aromatic esters. Hydrophilic ended (also referred
to as uncapped) PLGA has an end group hydrophilic in nature at the
polymer terminus. PLGA with a hydrophilic end groups at the polymer
terminus degrades faster than hydrophobic ended PLGA because it
takes up water and undergoes hydrolysis at a faster rate (Tracy et
al., Biomaterials 20:1057-1062 (1999)). Examples of suitable
hydrophilic end groups that may be incorporated to enhance
hydrolysis include, but are not limited to, carboxyl, hydroxyl, and
polyethylene glycol. The specific end group will typically result
from the initiator employed in the polymerization process. For
example, if the initiator is water or carboxylic acid, the
resulting end groups will be carboxyl and hydroxyl. Similarly, if
the initiator is a monofunctional alcohol, the resulting end groups
will be ester or hydroxyl.
[0093] Additional Agents
[0094] Other agents may be employed in the formulation for a
variety of purposes. For example, buffering agents and
preservatives may be employed. Preservatives which may be used
include, but are not limited to, sodium bisulfite, sodium
bisulfate, sodium thiosulfate, benzalkonium chloride,
chlorobutanol, thimerosal, phenylmercuric acetate, phenylmercuric
nitrate, methylparaben, polyvinyl alcohol and phenylethyl alcohol.
Examples of buffering agents that may be employed include, but are
not limited to, sodium carbonate, sodium borate, sodium phosphate,
sodium acetate, sodium bicarbonate, and the like, as approved by
the FDA for the desired route of administration. Electrolytes such
as sodium chloride and potassium chloride may also be included in
the formulation.
[0095] The biodegradable ocular implants can also include
additional hydrophilic or hydrophobic compounds that accelerate or
retard release of the active agent. Additionally, release
modulators such as those described in U.S. Pat. No. 5,869,079 can
be included in the implants. The amount of release modulator
employed will be dependent on the desired release profile, the
activity of the modulator, and on the release profile of the
glucocorticoid in the absence of modulator. Where the buffering
agent or release enhancer or modulator is hydrophilic, it may also
act as a release accelerator. Hydrophilic additives act to increase
the release rates through faster dissolution of the material
surrounding the drug particles, which increases the surface area of
the drug exposed, thereby increasing the rate of drug diffusion.
Similarly, a hydrophobic buffering agent or enhancer or modulator
can dissolve more slowly, slowing the exposure of drug particles,
and thereby slowing the rate of drug diffusion.
[0096] Release Kinetics
[0097] An implant within the scope of the present invention can be
formulated with an active agent (or a prodrug of an active agent)
dispersed within a biodegradable polymer matrix. Without being
bound by theory, it is believed that the release of the active
agent can be achieved by erosion of the biodegradable polymer
matrix and by diffusion of the particulate agent into an ocular
fluid, e.g., the vitreous, with subsequent dissolution of the
polymer matrix and release of the active agent. Factors which
influence the release kinetics of active agent from the implant can
include such characteristics as the size and shape of the implant,
the size of the active agent particles, the solubility of the
active agent, the ratio of active agent to polymer(s), the method
of manufacture, the surface area exposed, and the erosion rate of
the polymer(s). The release kinetics achieved by this form of
active agent release are different than that achieved through
formulations which release active agents through polymer swelling,
such as with crosslinked hydrogels. In that case, the active agent
is not released through polymer erosion, but through polymer
swelling and drug diffusion, which releases agent as liquid
diffuses through the pathways exposed.
[0098] The release rate of the active agent can depend at least in
part on the rate of degradation of the polymer backbone component
or components making up the biodegradable polymer matrix. For
example, condensation polymers may be degraded by hydrolysis (among
other mechanisms) and therefore any change in the composition of
the implant that enhances water uptake by the implant will likely
increase the rate of hydrolysis, thereby increasing the rate of
polymer degradation and erosion, and thus increasing the rate of
active agent release.
[0099] The release kinetics of the implants of the present
invention can be dependent in part on the surface area of the
implants. A larger surface area exposes more polymer and active
agent to ocular fluid, causing faster erosion of the polymer matrix
and dissolution of the active agent particles in the fluid.
Therefore, the size and shape of the implant may also be used to
control the rate of release, period of treatment, and active agent
concentration at the site of implantation. At equal active agent
loads, larger implants will deliver a proportionately larger dose,
but depending on the surface to mass ratio, may possess a slower
release rate. For implantation in an ocular region, the total
weight of the implant preferably ranges, e.g., from about 200-15000
.mu.g, usually from about 1000-5000 .mu.g. In one variation, the
total weight of the implant is about 1200 to about 1,800 .mu.g. In
another variation, the total weight of the implant is about 2400 to
about 3,600 .mu.g. Preferably, the implant has a weight between
about 100 .mu.g and about 2 mg.
[0100] The bioerodible implants are typically solid, and may be
formed as particles, sheets, patches, plaques, films, discs,
fibers, rods, and the like, or may be of any size or shape
compatible with the selected site of implantation, as long as the
implants have the desired release kinetics and deliver an amount of
active agent that is therapeutic for the intended medical condition
of the eye. The upper limit for the implant size will be determined
by factors such as the desired release kinetics, toleration for the
implant at the site of implantation, size limitations on insertion,
and ease of handling. For example, the vitreous chamber is able to
accommodate relatively large rod-shaped implants, generally having
diameters of about 0.05 mm to 3 mm and a length of about 0.5 to
about 10 mm. In one variation, the rods have diameters of about 0.1
mm to about 1 mm. In another variation, the rods have diameters of
about 0.3 mm to about 0.75 mm. In yet a further variation, other
implants having variable geometries but approximately similar
volumes may also be used.
[0101] The proportions of active agent, polymer, and any other
modifiers may be empirically determined by formulating several
implants with varying proportions. A USP approved method for
dissolution or release test can be used to measure the rate of
release (USP 23; NF 18 (1995) pp. 1790-1798). For example, using
the infinite sink method, a weighed sample of the drug delivery
device is added to a measured volume of a solution containing 0.9%
NaCl in water, where the solution volume will be such that the drug
concentration is after release is less than 20%, and preferably
less than 5%, of saturation. The mixture is maintained at
37.degree. C. and stirred slowly to ensure drug diffusion after
bioerosion. The appearance of the dissolved drug as a function of
time may be followed by various methods known in the art, such as
spectrophotometrically, HPLC, mass spectroscopy, etc.
[0102] Applications
[0103] Examples of ocular conditions which can be treated by the
implants and methods of the invention include, but are not limited
to, glaucoma, uveitis, macular edema, macular degeneration, retinal
detachment, ocular tumors, bacterial, fungal or viral infections,
multifocal choroiditis, diabetic retinopathy, proliferative
vitreoretinopathy (PVR), sympathetic opthalmia, Vogt
Koyanagi-Harada (VKH) syndrome, histoplasmosis, uveal diffusion,
and vascular occlusion. In one variation, the implants are
particularly useful in treating such medical conditions as uveitis,
macular edema, vascular occlusive conditions, proliferative
vitreoretinopathy (PVR), and various other retinopathies.
[0104] Methods of Implantation
[0105] The biodegradable implants can be inserted into the eye by a
variety of methods, including placement by forceps, by trocar, or
by other types of applicators, after making an incision in the
sclera. In some instances, a trocar or applicator may be used
without creating an incision. In a preferred variation, a hand held
applicator is used to insert one or more biodegradable implants
into the eye. The hand held applicator typically comprises an 18-30
GA stainless steel needle, a lever, an actuator, and a plunger.
Suitable devices for inserting an implant or implants into a
posterior ocular region or site includes those disclosed in U.S.
patent application Ser. No. 10/666,872.
[0106] The method of implantation generally first involves
accessing the target area within the ocular region with the needle,
trocar or implantation device. Once within the target area, e.g.,
the vitreous cavity, a lever on a hand held device can be depressed
to cause an actuator to drive a plunger forward. As the plunger
moves forward, it can push the implant or implant into the target
area (i.e. the vitreous).
[0107] Methods for Making Implants
[0108] Various techniques may be employed to make implants within
the scope of the present invention. Useful techniques include phase
separation methods, interfacial methods, extrusion methods,
compression methods, molding methods, injection molding methods,
heat press methods and the like.
[0109] Choice of the technique, and manipulation of the technique
parameters employed to produce the implants can influence the
release rates of the drug. Room temperature compression methods
result in an implant with discrete microparticles of drug and
polymer interspersed. Extrusion methods result in implants with a
progressively more homogenous dispersion of the drug within a
continuous polymer matrix, as the production temperature is
increased.
[0110] The use of extrusion methods allows for large-scale
manufacture of implants and results in implants with a homogeneous
dispersion of the drug within the polymer matrix. When using
extrusion methods, the polymers and active agents that are chosen
are stable at temperatures required for manufacturing, usually at
least about 50.degree. C. Extrusion methods use temperatures of
about 25.degree. C. to about 150.degree. C., more preferably about
60.degree. C. to about 130.degree. C.
[0111] Different extrusion methods may yield implants with
different characteristics, including but not limited to the
homogeneity of the dispersion of the active agent within the
polymer matrix. For example, using a piston extruder, a single
screw extruder, and a twin screw extruder will generally produce
implants with progressively more homogeneous dispersion of the
active. When using one extrusion method, extrusion parameters such
as temperature, extrusion speed, die geometry, and die surface
finish will have an effect on the release profile of the implants
produced.
[0112] In one variation of producing implants by a piston extrusion
methods, the drug and polymer are first mixed at room temperature
and then heated to a temperature range of about 60.degree. C. to
about 150.degree. C., more usually to about 130.degree. C. for a
time period of about 0 to about 1 hour, more usually from about 0
to about 30 minutes, more usually still from about 5 minutes to
about 15 minutes, and most usually for about 10 minutes. The
implants are then extruded at a temperature of about 60.degree. C.
to about 130.degree. C., preferably at a temperature of about
75.degree. C.
[0113] In an exemplary screw extrusion method, the powder blend of
active agent and polymer is added to a single or twin screw
extruder preset at a temperature of about 80.degree. C. to about
130.degree. C., and directly extruded as a filament or rod with
minimal residence time in the extruder. The extruded filament or
rod is then cut into small implants having the loading dose of
active agent appropriate to treat the medical condition of its
intended use.
[0114] Implant systems according to the invention can include a
combination of a number of bioerodible implants, each having unique
polymer compositions and drug release profiles that when
co-administered provide for an extended continuous release of drug.
Examples of fast release implants include those made of certain
lower molecular weight, fast degradation profile polylactide
polymers, such as R104 made by Boehringer Ingelheim GmbH, Germany,
which is a poly(D,L-lactide) with a molecular weight of about
3,500. Examples of medium release implants include those made of
certain medium molecular weight, intermediate degradation profile
PLGA co-polymers, such as RG755 made by Boehringer Ingelheim GmbH,
Germany, which is a poly(D,L-lactide-co-glycolide with wt/wt 75%
lactide:25% glycolide, a molecular weight of about 40,000 and an
inherent viscosity of 0.50 to 0.70 dl/g. Examples of slow release
implants include those made of certain other high molecular weight,
slower degradation profile polylactide polymers, such as R203/RG755
made by Boehringer Ingelheim GmbH, Germany, for which the molecular
weight is about 14,000 for R203 (inherent viscosity of 0.25 to 0.35
dl/g) and about 40,000 for RG755.
[0115] Examples of implants include those formed with RG755, R203,
RG503, RG502, RG 502H as the first polymer, and RG502, RG 502H as
the second polymer. Other polymers that can be used include PDL
(poly(D,L-lactide)) and PDLG (poly(D,L-lactide-co-glycolide))
polymers available from PURAC America, Inc. Lincolnshire, Ill.
Poly(caprolactone) polymers can also be used. The characteristics
of the specified polymers are (1) RG755 has a molecular weight of
about 40,000, a lactide content (by weight) of 75%, and a glycolide
content (by weight) of 25%; (2) R203 has a molecular weight of
about 14,000, and a 100%; (30 RG503 has a molecular weight of about
28,000, a lactide content of 50%, and a glycolide content of 50%;
(4) RG502 has a molecular weight of about 11,700 (inherent
viscosity of 0-16 to 0.24 dl/g), a lactide content of 50%, and a
glycolide content of 50%, and; (5) RG502H has a molecular weight of
about 8,500, a lactide content of 50%, a glycolide content of 50%
and free acid at the end of polymer chain.
[0116] Generally, if inherent viscosity is 0.16 the molecular
weight is about 6,327, and if the inherent viscosity is 0.28 the
molecular weight is about 20670.
[0117] According to our invention continual or substantially
continual release of drug at levels corresponding to at least 10
ng/ml of dexamethasone or dexamethasone equivalent for between
about 5-40 days can be achieved.
[0118] This may be more clearly understood with reference to FIG. 5
which illustrates a cross-sectional view of a human eye 10 in order
to illustrate the various sites that may be suitable for
implantation of an implant in accordance with the present
invention.
[0119] The eye 10 comprises a lens 12 and encompasses the vitreous
chamber 14. Adjacent to the vitreous chamber is the optic part of
the retina 16. Implantation may be into the vitreous 14,
intraretinal 16 or subretinal 18. The retina 16 is surrounded by
the choroid 20. Implantation may be intrachoroidal or
suprachoroidal 22. Between the optic part of the retina and the
lens, adjacent to the vitreous, is the pars plana 24. Surrounding
the choroid 20 is the sclera 26. Implantation may be intrascleral
26 or episcleral 28. The external surface of the eye is the cornea
30. Implantation may be epicorneal 30 or intra-corneal 32. On the
external surface of the eye is the conjunctiva 34. Behind the
cornea is the anterior chamber 36, behind which is the lens 12. The
posterior chamber 38 surrounds the lens, as shown in the figure.
Opposite from the external surface is the optic nerves, and the
arteries and vein of the retina. Implants into the meningeal spaces
40, the optic nerve 42 and the intraoptic nerve 44 allows for drug
delivery into the central nervous system, and provide a mechanism
whereby the blood-brain barrier may be crossed.
[0120] Other sites of implantation include the delivery of
anti-tumor drugs to neoplastic lesions, e.g. tumor, or lesion area,
e.g. surrounding tissues, or in those situations where the tumor
mass has been removed, tissue adjacent to the previously removed
tumor and/or into the cavity remaining after removal of the tumor.
The implants may be administered in a variety of ways, including
surgical means, injection, trocar, etc.
EXAMPLES
[0121] The following examples illustrate aspects and embodiments of
the invention.
Example A
Rapid Loss of Therapeutic Effect Upon Cessation of Ocular
Medication
[0122] To examine loss or reduction of a therapeutic effect (i.e.
IOP lowering) upon cessation of chronic medication administration
used to treatment a chronic ocular condition, three different
populations of patients with glaucoma were examined.
[0123] 1. A population of twenty patients with glaucoma was
examined. It was determined that on day 28 after the patients had
been receiving topical Lumigan 0.03% once a day for three weeks and
then twice a day for one week, the mean IOP on day 28 was -8 mm Hg
from baseline. Yet on day 30 after 2 days with no medication
administered it was determined that the mean IOP of the 20 patients
was only -6 mm Hg from baseline.
[0124] 2. Similarly for a separate population of 20 patients with
glaucoma it was determined that on day 28 after the patients had
been receiving topical timolol 0.5% twice a day for four weeks, the
mean IOP on day 28 was -4 mm Hg from baseline. Yet on day 30 after
2 days with no medication administered the mean IOP of the 20
patients was only -2 mm Hg from baseline.
[0125] 3. For a separate (third) population of 18 patients with
glaucoma it was determined that on day 14 after the patients had
been receiving topical brimonidine for 14 days, the mean IOP on day
14 was -2 mm Hg from baseline. Yet on day 15 after 24 hours with no
medication administered the mean IOP of the 18 patients was only
-0.8 mm Hg from baseline.
[0126] The results set forth by Example A show that within a short
period of a day or two after stopping chronic use of various
anti-glaucoma medications, the mean intraocular pressure of all
patient populations increased significantly, thereby showing that a
chronic intraocular condition requires chronic treatment to obtain
an ongoing therapeutic effect.
Example 1
Manufacture of Compressed Tablet Implants
[0127] Micronized dexamethasone (Pharmacia, Peapack, N.J.) and
micronized hydrophobic end 50/50 PLGA (Birmingham Polymers, Inc.,
Birmingham, Ala.) were accurately weighed and placed in a stainless
steel mixing vessel. The vessel was sealed, placed on a Turbula
mixer and mixed at a prescribed intensity, e.g., 96 rpm, and time,
e.g., 15 minutes. The resulting powder blend was loaded one unit
dose at a time into a single-cavity tablet press. The press was
activated at a pre-set pressure, e.g., 25 psi, and duration, e.g.,
6 seconds, and the tablet was formed and ejected from the press at
room temperature. The ratio of dexamethasone to PLGA was 70/30 w/w
for all compressed tablet implants.
Example 2
Manufacture of Extruded Implants
[0128] Micronized dexamethasone (Pharmacia, Peapack, N.J.) and
unmicronized PLGA were accurately weighed and placed in a stainless
steel mixing vessel. The vessel was sealed, placed on a Turbula
mixer and mixed at a prescribed intensity, e.g., 96 rpm, and time,
e.g., 10-15 minutes. The unmicronized PLGA composition comprised a
30/10 W/W mixture of hydrophilic end PLGA (Boehringer Ingelheim,
Wallingford, Conn.) and hydrophobic end PLGA (Boehringer Ingelheim,
Wallingford, Conn.). The resulting powder blend was fed into a DACA
Microcompounder-Extruder (DACA, Goleta, Calif.) and subjected to a
pre-set temperature, e.g., 115.degree. C., and screw speed, e.g.,
12 rpm. The filament was extruded into a guide mechanism and cut
into exact lengths that corresponded to the designated implant
weight. The ratio of dexamethasone to total PLGA (hydrophilic and
hydrophobic end) was 60/40 w/w for all extruded implants.
[0129] Thus, the implant is composed of dexamethasone and a PLGA
[poly(D,L-lactide-co glycolide)] polymer matrix. There are two
sizes of the implant: one containing about 350 .mu.g of
dexamethasone and one containing about 700 .mu.g of dexamethasone.
Both sizes of implant contain 60% by weight of drug and 40% by
weight of polymer.
[0130] As set forth above, the implants can be manufactured by a
continuous extrusion process by double extrusion using a twin-screw
extruder. The implants can have a microstructure consisting of a
micronized dexamethasone particles homogeneously dispersed in a
continuous polymer matrix.
[0131] The implants can be approximately cylindrical in shape. The
700 .mu.g implants can have a diameter of about 460 .mu.m (0.460
mm) and a length of about 6 mm, and the 350 .mu.g implant can have
the same diameter and a length of about 3 mm.
[0132] The total weight of the 700 .mu.g implants can be about 1.2
mg and the total weight of the 350 .mu.g implant can be about 0.6
mg. Weight tolerance for a population of implants can be about
.+-.10% by weight or less.
[0133] The PLGA polymer matrix can be a mixture of acid end and
ester end polymers. PLGA molecules are terminated at one end by an
--OH (hydroxyl) group and at the other end by a --COOR group where
for acid end molecules R.dbd.H and for ester end molecules R=alkyl.
The PLGA used in the Posurdex.TM. implant can be a mixture of 75%
by weight acid end PLGA and 25% by weight ester end PLGA. That is,
the implants will be about 60% by weight drug, about 30% by weight
acid end PLGA, and about 10% by weight ester end PLGA. Both acid
and ester end PLGA will contain 50% lactide units and 50% glycolide
units.
Example 3
Method and Devices for Placing Implants Into the Vitreous
[0134] Implants were placed into the posterior segment of the right
eye of New Zealand White Rabbits by incising the conjunctiva and
sclera between the 10 and 12 o'clock positions with a 20-gauge
microvitreoretinal (MVR) blade. Fifty to 100 .mu.L of vitreous
humor was removed with a 1-cc syringe fitted with a 27-gauge
needle. A sterile trocar, preloaded with the appropriate implant
(drug delivery system, DDS), was inserted 5 mm through the
sclerotomy, and then retracted with the push wire in place, leaving
the implant in the posterior segment. Sclerae and conjunctivae were
than closed using a 7-0 Vicryl suture. Suitable applicators which
have been used to place implants of Examples 1 and 2 in the
vitreous of human eyes are set forth in U.S. patent application
Ser. No. 10/666,872.
Example 4
Comparison of Tablet and Extruded Dexamethasone Bioerodible Vitreal
Implants Over 72 Hours
[0135] Examples 4 and 5 set forth a pre-clinical study carried out
to evaluate biodegradable polymeric implants inserted in the
posterior chamber (i.e. in the vitreous) of an eye. The implant
contained the anti-inflammatory steroid dexamethasone as the active
agent. These implant are referred to below a "DEX PS DDS" implants.
These implants and can be made as a tablet ("T") or as an extrusion
("E"), using a continuous extrusion process.
[0136] The dexamethasone can be used as the acetate salt or in the
form of the sodium phosphate ester. In opthalmology dexamethasone
sodium phosphate has been widely used for over 40 years as a
topically applied solution (0.1%). The maximum safe dose of
dexamethasone for intravitreal injection or for release from an
implanted sustained-release devices is believed to be about 4,800
.mu.g to 5,000 .mu.g. Thus, the total dose of 350 .mu.g or 700
.mu.g delivered with the DEX PS DDS is a non-toxic dose. The test
implant DEX PS DDS is a polymeric matrix designed to deliver
dexamethasone in vivo over a time period of approximately 35
days.
[0137] As set forth below, two animal studies were carried out (a
72 hour study and an 84 day study), with the DEX PS DDS, using both
a tablet (tableted implant) and an extruded form of the implant, to
evaluate the intraocular and systemic pharmacokinetics (PK) of this
intraocular drug delivery system.
[0138] These experiments showed that both the tableted and extruded
dosage forms can release 700 .mu.g or 350 .mu.g of dexamethasone
over about the 35 days it takes the implant to bioerode.
[0139] A 72 hour experiment was carried out to compare the
pharmacokinetics of tableted and extruded forms at two dose levels
of DEX PS DDSO upon implantation into the posterior segment
(vitreous) of the eyes of New Zealand white rabbits.
[0140] The four types of implants used in this experiment were
designated as 350 .mu.g extruded DEX PS DDS ("350E"), 700 .mu.g
extruded DEX PS DDS ("700E"), 350 .mu.g tableted DEX PS DDS
("350T") and 700 .mu.g tableted DEX PS DDS ("700T").
[0141] On Day 0, 120 male New Zealand white rabbits each received 1
of the 4 types of test implants (30 rabbits per test implant) in
the posterior segment (vitreous) of the right eye. The left eye of
each animal served as a control. Euthanasia and necropsy were
performed at 3, 6, 12, 24, and 72 hours after dosing. Prior to
euthanasia, plasma was collected for evaluation of plasma
dexamethasone concentrations. Aqueous and vitreous humor samples
were collected from the test and control eyes at necropsy, and the
vitreous humor sample was divided into two sections. The experiment
was carried out in compliance with Good Laboratory Practice (GLP
Regulations, 21 CFR, Part 58). The section of the vitreous humor
containing the DEX PS DDS remnant(s) was analyzed for dexamethasone
concentrations and vitreous humor and aqueous humor of the treated
eye were assayed for dexamethasone concentrations, as was the
vitreous and the aqueous humor of the control eye, and the
plasma.
[0142] No mortality occurred following implantation of the DEX PS
DDS. Anesthesia and surgical recovery led to minor weight loss in
28 of 48 animals necropsied at 24 and 72 hours, but no other
morbidity was reported during the experiment.
[0143] As shown by FIG. 1 concentration profiles in the vitreous
humor were similar for the 350E and 700E implants of DEX PS DDS,
with peak mean vitreous humor concentrations observed at 3 hours
(194.65 ng/mL and 912.33 ng/mL, respectively) and 6 hours (163.40
ng/mL and 918.50 ng/mL, respectively).
[0144] Mean dexamethasone concentrations with the extruded dosage
form were considerably higher for the 700 .mu.g dose level than for
the 350 .mu.g dose level. Between 6 and 24 hours, dexamethasone
concentrations declined, and then, for the extruded implants,
increased from 24 to 72 hours. This pattern of drug release
suggests that the initial concentrations of dexamethasone observed
in the vitreous resulted from surface release of dexamethasone,
which led to early peak mean concentrations. This initial peak in
concentration was followed by a decline in mean drug concentration
and then an increase in drug concentration with the initiation of
dexamethasone release from the polymer matrix (see FIG. 1).
[0145] Initial mean vitreous humor dexamethasone concentrations at
3 and 6 hours were lower for the tablet dosage form than the
extruded dosage form at both dose levels. However, the tablet
dosage form demonstrated higher drug concentrations than the
extruded dosage form at all remaining time points (12, 24 and 72
hours) at both dose levels. Overall, peak mean vitreous humor
dexamethasone concentrations were similar between the two dosage
forms at corresponding dose levels. The mean vitreous humor
concentrations for the tablet dosage form within each dose level
did not change substantially over the 72-hour study period. Peak
mean vitreous humor concentrations of dexamethasone were observed
at 24 hours for both the 350T and 700T groups (261.82 ng/mL and
716.33 ng/mL, respectively) (FIG. 1).
[0146] The proportion of dexamethasone released from the DEX PS DDS
over the 72-hour study period for the extruded dose levels (350E
and 700E) was consistent across both dose levels at approximately
15%. Likewise the tablet dosage form also had similar dexamethasone
release profiles for both dose levels (350T and 700T), but released
a significantly greater proportion of the total dexamethasone
(approximately 35%) by the end of the 72-hour study (FIG. 2).
[0147] Consistent with the greater release of dexamethasone from
the tablet dosage form during this 72-hour study, higher mean
concentrations of drug were measured in the aqueous humor at all
sampling points for both the 350T and 700T groups when compared to
the 350E and 700E groups. In general, for both dosage forms and
dose levels, the mean aqueous humor concentrations of dexamethasone
were approximately 10 times lower than the mean vitreous humor
concentrations of dexamethasone.
[0148] Plasma dexamethasone concentrations were observed at all
sampling points for the tablet dosage form, but only minimally
above the limit of quantification (1.00 ng/mL). Measurable
dexamethasone concentrations were not observed in the plasma of
animals in the 350E group, and plasma concentrations were
measurable, but at very low concentrations, for the 700E group at
3, 6 and 12 hours.
[0149] With a single exception, mean dexamethasone concentrations
were below the limit of quantification in the vitreous and aqueous
humor of the control eyes for both dosage forms at all dose levels.
The exception was observed in the 350T dose control group in which
a vitreous humor concentration of 2.98 ng/mL was observed at 6
hours.
CONCLUSION
[0150] Although release profiles were similar among dose levels
(350 .mu.g and 700 .mu.g) within each dosage form, the extruded
dosage form released approximately 15% of the dose over the study
period while the tablet dosage form released approximately 35% over
the same period.
[0151] The results of this study demonstrate that peak mean
vitreous humor concentrations of dexamethasone are similar for the
tablet and extruded dosage forms over the 72-hour study period. For
both dosage forms the mean concentrations of dexamethasone observed
in the vitreous humor, aqueous humor, and plasma were consistent
with the dose levels administered.
Example 5
Comparison of Tablet and Extruded Dexamethasone Bioerodible Vitreal
Implants Over 84 Days
[0152] An 84 day experiment was carried out to compare the
pharmacokinetics of tableted and extruded forms at two dose levels
of DEX PS DDS.RTM. upon implantation into the posterior segment
(vitreous) of the eyes of New Zealand white rabbits.
[0153] This experiment was designed to evaluate the intraocular
(vitreous and aqueous humor) and systemic (plasma) pharmacokinetics
(PK) of two dosage forms of DEX PS DDS, tableted and extruded, with
each dosage form evaluated at two dose levels. The same four test
implant types used in Example 1 were used in this experiment: 350
.mu.g extruded DEX PS DDS (350E), 700 .mu.g extruded DEX PS DDS
(700E), 350 .mu.g tableted DEX PS DDS (350T) and 700 .mu.g tableted
DEX PS DDS (700T).
[0154] On Day 0, 312 male New Zealand White rabbits each received 1
of the 4 test implants (78 rabbits per test article) in the
posterior segment (vitreous) of the right eye. The left eye of each
animal served as a control. Euthanasia and necropsy were performed
at Days 1, 3, 7, 14, 21, 28, 35, 45, 56, 70, and 86. Prior to
euthanasia, plasma was collected for evaluation of plasma
dexamethasone levels. Vitreous humor samples were collected at
necropsy, and the vitreous was divided into two sections: the
section containing the DEX PS DDS remnant(s) and the remaining
vitreous humor section without DEX PS DDS remnants were
analyzed.
[0155] The experiment was carried out in compliance with Good
Laboratory Practice (GLP Regulations, 21 CFR, Part 58). The section
of the vitreous humor containing the DEX PS DDS remnant(s) was
analyzed for dexamethasone concentrations and vitreous humor and
aqueous humor of the treated eye were assayed for dexamethasone
concentrations, as was the vitreous and the aqueous humor of the
control eye, and the plasma. A subset of twenty-four animals (6 per
test implant) underwent weekly ophthalmic examinations to monitor
the polymer matrix dissolution of the test article and dissolution
was evaluated in all animals with test article implants prior to
euthanasia. Dissolution was evaluated by a veterinary
ophthalmologist using a numerical grading scale. No mortality
occurred following implantation of the DEX PS DDS. Anesthesia and
surgical recovery led to minor weight loss early in the study,
however none of the animals necropsied after Day 45 demonstrated an
overall weight loss between surgery and necropsy, indicating that
any early weight loss was regained.
[0156] Vitreous humor concentrations of dexamethasone were observed
in the 350E group on Day 1 (10.66 ng/mL) through Day 28 (6.99
ng/mL), with peak mean concentrations at Day 14 (111.30 ng/mL) and
Day 21 (105.10 ng/mL). In the 700E group, mean vitreous humor
concentrations of dexamethasone were measured from Day 1 (52.63
ng/mL) through Day 28 (119.70 ng/mL), with peak mean concentrations
observed on Day 14 (435.60 ng/mL) and Day 21 (527.50 ng/mL). By Day
35, mean concentrations of dexamethasone were at or below the limit
of quantification (2.50 ng/mL) for both levels of the extruded
dosage form (FIG. 3).
[0157] For the 350T group, peak mean dexamethasone concentrations
in the vitreous humor were identified on Day 1 (142.20 ng/mL) and
Day 3 (89.58 ng/mL), with measurable concentrations observed
through Day 56 (2.79 ng/mL). For the 700T group, peak mean
dexamethasone concentrations were also observed at Day 1 (198.56
ng/mL) and Day 3 (193.06 ng/mL), with measurable concentrations
observed intermittently through Day 86 (3.03 ng/mL) (FIG. 3).
[0158] The percent of dexamethasone released for each dosage form
at each dose level was determined by assaying the section of the
vitreous humor containing the DEX PS DDS remnants. Overall, the
extruded dosage form provided a more consistent release of
dexamethasone as evidenced by the lower standard deviations over
the sampling period. For both dosage forms and dose levels, the
mean percent of dexamethasone released by Day 35 was >90% (FIG.
4).
[0159] In the treated right eye, measurable concentrations of
dexamethasone were found in the aqueous humor for both dosage forms
and both dose levels at most time points up to Day 28, with peak
mean aqueous humor concentrations paralleling peak mean vitreous
humor concentrations. However, at most time points, peak mean
plasma concentrations of dexamethasone were below, at or slightly
above the limit of quantification (1.00 ng/mL). In the vitreous and
aqueous humor of the control eyes dexamethasone content was
generally below the limit of quantification.
[0160] Polymer matrix dissolution was evaluated in each group of
animals at necropsy. Complete dissolution of the polymer matrix was
observed at approximately 3 months in 58% of the animals receiving
the extruded dosage form, and in 17% of the animals receiving the
tablet dosage form, suggesting improved polymer matrix dissolution
for the extruded dosage form.
[0161] In a subset of 24 animals, polymer matrix dissolution was
assessed weekly. For the extruded dosage form, significant
dissolution (1-24% remaining) had occurred in all but one eye by
Day 46. Similarly, for the tablet dosage form, significant
dissolution had occurred in all eyes by Day 57. Complete polymer
matrix dissolution was observed by approximately 5 months for 67%
of the extruded dosage form group and for 58% of the tablet dosage
form group.
[0162] In summary, both dosage forms released an equivalent dose of
dexamethasone, i.e., either 350 .mu.g or 700 .mu.g, over
approximately 35 days, but achieved peak concentrations at
different time points during the release period. Gradual, less
variable release of dexamethasone, and more rapid dissolution of
the polymer matrix were observed with the extruded dosage form.
Example 6
Extended Treatment of Macular Edema with an Intravitreal
Dexamethasone Implant
[0163] An experiment was carried out with a biodegradable drug
delivery system for implanting into the vitreous of the eye and
release of dexamethasone (referred to hereafter as a "DEX PS DDS").
Such an implant can be used for the treatment of ocular conditions,
such as macular edema.
[0164] Implants made according to the methods of Examples 1 and 2
were used. These implants form an intravitreal drug delivery
system, which can be referred to as a Dexamethasone Posterior
Segment Drug Delivery System (DEX PS DDS.RTM.), can deliver a 350
.mu.g or 700 .mu.g dose of dexamethasone intravitreally over
approximately 35 days, allowing for a lower total dose and
sustained drug levels to the target areas. DEX PS DDS is composed
of dexamethasone homogeneously dispersed into a biodegradable
matrix of copolymers of lactic acid and glycolic acid, PLGA (poly
[lactic-glycolic] acid), a material commonly used in medical
devices such as absorbable sutures. Dexamethasone is released
gradually into the back of the eye over a period of approximately
35 days. The DEX PS DDS does not need to be removed since the
copolymer dissolves completely over time.
[0165] By effectively delivering a sustained release
anti-inflammatory drug intravitreally, DEX PS DDS can offer
patients and clinicians a valuable new therapeutic option in the
treatment of persistent macular edema that has persisted despite
intervention, while reducing the potential for side-effects
typically observed from steroid administration through other routes
of delivery (e.g. systemic, etc.).
[0166] The objective of the experiment was to compare the safety
and efficacy of two doses of DEX PS DDS (350 .mu.g and 700 .mu.g)
versus observation (i.e. patients in which no implant was used) in
the treatment of persistent macular edema (PME) persisting at least
90 days after laser treatment or after 90 days of medical
management by a physician. Patients with PME associated with
diabetic retinopathy, uveitis, retinal vein occlusion, and
Irvine-Gass Syndrome were in the experiment.
[0167] A total of 306 patients, ages .gtoreq.12 years old, with
persistent macular edema associated with diabetic retinopathy,
uveitis, branch retinal vein occlusion (BRVO), central retinal vein
occlusion (CRVO) or Irvine-Gass Syndrome, persisting for at least
90 days following treatment were part of this 180-day study. At
baseline, each patient provided written informed consent and a
complete medical history including ocular history and prior
medications (within the last 30 days). Potential study participants
underwent measurements of best-corrected visual acuity (BCVA) based
on ETDRS and intraocular pressure (IOP), and were examined for
clinical signs of anterior chamber cells, anterior chamber flare,
anterior vitreous cells, cataract, vitreal haze/retinal
obscuration, vitreous/retinal hemorrhage, retinal detachment/tear
and macular edema. Patients also underwent fluorescein angiography,
fundus photography, and optical coherence tomography. Diabetic
patients were tested for HbA.sub.1c and pre-menopausal women
underwent urine pregnancy testing. For the purposes of this
experiment persistent macular edema was defined as retinal
thickening at the center of the fovea, visual acuity equal to or
worse than 20/40, and angiographic evidence of leakage in the
perifoveal capillary network.
[0168] After signing the informed consent form and determination of
eligibility, patients were randomly assigned to treatment with 350
.mu.g DEX PS DDS, or 700 .mu.g DEX PS DDS, or observation.
[0169] DEX PS DDS (350 .mu.g or 700 .mu.g dexamethasone) was
surgically implanted in the study eye of patients in the two active
treatment groups. Insertion was performed through an incision in
the pars plana inferotemporally, unless contraindicated during
surgery by the Investigator. After closure, the suture knot was
buried and subconjunctival and topical antibiotics were used
prophylactically. If the delivery system became contaminated or
damaged prior to insertion, it was replaced with a new, sterile
system.
[0170] Visual Acuity
[0171] The visual acuity of patients in this study was measured
according to the standard procedure developed for the Early
Treatment Diabetic Retinopathy Study (ETDRS) and adapted for the
Age-Related Eye Disease Study Protocol (AREDS) and this study.
Visual acuity testing was required at a distance of 4-meters and,
for subjects with sufficiently reduced vision, at 1-meter. ETDRS
Charts 1 and 2 were used for testing the right and left eye,
respectively, and Chart R was used for refraction.
[0172] Contrast Sensitivity
[0173] Contrast sensitivity, the ability of the eye to discern
subtle degrees of contrast and size, is a sensitive measure of
visual function which can be affected by the presence of retinal
disease. Contrast sensitivity testing was performed as an
additional measure of visual function using standardized,
preprinted charts and standardized photopic and mesopic
illumination by certified examiners. The outcome was measured as
the lowest level of contrast at which a patient could distinguish
pattern size displayed using a sine-wave contrast sensitivity
vision test.
[0174] Fluorescein Angiography
[0175] Fluorescein angiography was conducted prior to randomization
to provide angiographic evidence of leakage involving the
perifoveal capillary networks and at select follow-up visits to
assess anatomical improvement in macular edema. A central reading
laboratory, FPRC (Fundus Photograph Reading Center, Madison, Wis.),
was used to perform all readings. Readers were masked to patient
treatment assignments.
[0176] Fundus Photography
[0177] Fundus photography was performed to assess macular
thickness, an anatomical measure of macular edema, using standard
techniques by certified photographers at each site. The photographs
were assessed by masked readers at a central reading laboratory
(FPRC).
[0178] Optical Coherence Tomography
[0179] Optical coherence tomography (OCT) is a laser-based
non-invasive, diagnostic system providing high-resolution images of
the retina (10 .mu.m). Macular thickness, an anatomical indicator
of macular edema, was assessed by a central reading laboratory
(FPRC) from images obtained at Baseline and select follow-up
visits. Readers were masked to patient treatment assignments.
[0180] Schedule of Exams
[0181] Patients, including both treatment groups and the
observation group, were assessed according to the following
schedule: [0182] BCVA by ETDRS (Baseline, Days 7, 30, 60, 90, 180
or Early Termination); [0183] Contrast sensitivity (Baseline, Days
30, 60, 90 or Early Termination); [0184] Intraocular pressure
(Baseline, Days 1, 7, 30, 60, 90, 180 or Early Termination); [0185]
Slit lamp biomicroscopy with fundus contact lens (Baseline, Days 1,
7, 30, 60, 90 or Early Termination) for clinical signs of macular
edema; [0186] Slit lamp assessment (Baseline, Days 1, 7, 30, 60,
90, 180 or Early Termination) for anterior chamber cells, anterior
chamber flare, anterior vitreous cells, and cataract(s); [0187]
Indirect opthalmoscopy (Baseline, Days 1, 7, 30, 60, 90, 180 or
Early Termination) for vitreal haze/retinal obscuration,
vitreous/retinal hemorrhage, retinal detachment/tear. DEX PS DDS
was observed on Days 30, 60, 90, 180 or Early Termination only
(with scleral depression); [0188] Fluorescein angiography
(Baseline, Days 30, 90 or Early Termination); [0189] Fundus
photography (Baseline, Day 0 [DEX PS DDS-treated group only if
deemed necessary] Day 1 [Observation Group only if deemed
necessary], Days 30, 60, 90 or Early Termination); [0190] Optical
coherence tomography (OCT) for macular thickness quantification at
clinical sites where test available (Baseline, Days 30, 90 or Early
Termination); [0191] Vital signs: blood pressure (Baseline, Days 1,
7, 30, 60, 90); [0192] HbA.sub.1c--Baseline, Days 30, 60, 90 or
Early Termination (if diabetic).
[0193] Efficacy
[0194] The primary efficacy parameter was BCVA (by ETDRS)
improvement at the Day 90 follow-up visit. The BCVA improvement
rate was defined as the proportion of subjects who had 2 lines or
more improvement from baseline.
[0195] Secondary efficacy parameters were: [0196] BCVA improvement
at the Day 30 and Day 60 follow-up visits from baseline; [0197]
Mean change in the BCVA in LogMAR (log of the minimum angle of
resolution) at the Day 30, Day 60, and Day 90 follow-up visits from
baseline; [0198] Mean change in measurements based on the contrast
sensitivity evaluation performed at the Day 30, Day 60 and Day 90
follow-up visits from baseline; [0199] Mean change in measurements
based on the fluorescein angiography evaluation performed at the
Day 30 and Day 90 follow-up visits; [0200] Mean change in
measurements based on the fundus photography evaluation performed
at the Day 30, Day 60 and Day 90 follow-up visits; [0201] Mean
change in the retinal thickness in 1-mm diameter center subfield
based on the OCT evaluation at the Day 30 and Day 90 follow-up
visits from baseline; [0202] Mean change in measurements based on
the clinical signs of persistent macular edema (PME) evaluation by
slit lamp biomicroscopy performed at the Day 1, Day 7, Day 30, Day
60 and Day 90 follow-up visits; [0203] Mean change in BCVA from
Baseline to the Day 7, 30, Day 60 and Day 90 follow-up visits.
[0204] Results
[0205] A total of 315 patients with persistent macular edema (PME)
were enrolled in the clinical study. One hundred five (105)
patients were assigned to each of the three study groups, i.e., DEX
PS DDS 350 .mu.g, DEX PS DDS 700 .mu.g, or observation only. Five
patients assigned to the 350 .mu.g treatment group and 4 patients
assigned to the 700 .mu.g treatment group withdrew before DEX PS
DDS treatment was initiated due to a change in eligibility status
since randomization or personal reasons and therefore were not
included within the intent-to-treat population. Of the total
intent-to-treat (ITT) study population (n=306), 51.3% of the
patients were male and 48.7% were female, with 9 patients less than
40 years of age (2.9%), 119 patients in the 40 to 65 year range
(38.9%), and 178 patients over 65 years of age (58.2%). The mean
age was 66 years (SD=11.9) consistent with the greater prevalence
of eye pathologies among older adults. The majority of patients
were Caucasian (77.8%), with the remaining patients from the
following ethnic groups: Black (7.5%), Hispanic (11.1%), Asian
(2.6%), and Native American (1.0%).
[0206] Improved Visual Acuity
[0207] As shown in Table 1, use of both the 350 .mu.g and the 700
.mu.g DEX PS DDS resulted in visual acuity improvement of two or
more lines in BCVA at Day 30, Day 90 and as well at Day 180. All
the visual acuity improvement percentages shown in Table 1 were
greater at each time (Day 90 and Day 180) and for each type of
implant (350 .mu.g and 700 .mu.g) than was the visual acuity
improvement percentage seen in the patients in the observation
group.
[0208] Thus, it was demonstrated that use of an implant according
to the method set forth herein permits a patients' visual acuity to
improve and that the patient's improved visual acuity can be
retained for a period of time long after the implant has released
all the dexamethasone.
TABLE-US-00001 TABLE 1 Improved Visual Acuity 30, 60 and 90 Days
after Placement of Intravitreal Implant DEX PS DDS DEX PS DDS 350
.mu.g 700 .mu.g Observation group (n = 100) (n = 101) (n = 105) Day
30 BCVA n 89 93 94 .gtoreq.2 line gain 21% 22% 16% .gtoreq.3 line
gain 9% 13% 6% Day 90 BCVA n 92 98 100 .gtoreq.2 line gain 26% 37%
19% .gtoreq.3 line gain 13% 16% 9% Day 180 BCVA n 92 98 100
.gtoreq.2 line gain 27% 36.% 19% .gtoreq.3 line gain 13% 19% 8%
[0209] Improved Visual Contrast Sensitivity
[0210] Change in contrast sensitivity, an assessment of visual
function, was measured at baseline, and at Days 30, 60, and 90
using a sine-wave contrast sensitivity vision test. As shown by
Table 2, the LOCF mean Contrast Sensitivity Score at 1.5 cpd (Patch
A) was higher in patients in both DEX PS DDS treatment groups
compared to the observation group at Day 60 (p<0.001) and Day 90
(p=0.006). The improvement appeared first among those in the 350
.mu.g treatment group at Day 30 (p=0.028), but by Day 60 patients
in both the 350 .mu.g and the 700 .mu.g treatment groups
experienced significant visual function improvement (p<0.001 and
p=0.011, respectively). This improvement was maintained to Day 90
(p=0.004 and p=0.010, respectively). A similar treatment effect
(data not shown) on LOCF mean Contrast Sensitivity Score at 3.0 cpd
(Patch B) was observed for both the 350 .mu.g and the 700 .mu.g DEX
PS DDS treatment groups, compared to the observation group, by Day
60 (p<0.001 and p=0.030, respectively), and continued through
Day 90 for both treatment groups (p=0.021 and p=0.007,
respectively).
[0211] Thus, it was demonstrated that use of an implant according
to the method set forth herein permits a patients' visual contrast
sensitivity to improve and that the patient's improved visual
contrast sensitivity can be retained for a period of time long
after the implant has released all the dexamethasone.
TABLE-US-00002 TABLE 2 Improved Visual Contrast Sensitivity 30
Days, 60 Days and 90 Days after Placement of Intravitreal Implant
Treatment Group DEX PS DDS DEX PS DDS Observation 350 .mu.g 700
.mu.g Group Change from 0.89 0.56 0.38 Baseline at Day 30 Change
from 1.21 0.80 0.13 Baseline at Day 60 Change from 1.02 0.97 0.33
Baseline at Day 90
[0212] Improved (Decreased) Retinal Thickness (OCT)
[0213] Change in retinal thickness, an anatomical measure of
macular edema, was assessed by Optical Coherence Tomography (OCT)
at Days 30 and 90. Patients who had baseline and at least one
follow-up evaluation were included in this analysis. As shown by
Table 3, the LOCF average retinal thickness score was improved by
Day 30 for both treatment groups as compared to the observation
group (p<0.001 for 350 .mu.g and 700 .mu.g DEX PS DDS). This
improvement continued to Day 90 for both treatment groups, with a
significantly greater decrease in retinal thickness in the 700
.mu.g treatment group (p<0.001) and the 350 .mu.g treatment
group (p=0.016) compared to the observation group.
[0214] Thus, it was demonstrated that use of an implant according
to the method set forth herein permits a patients' aberrant retinal
thickness to improve and that the patient's improved (decreased)
retinal thickness can be retained for a period of time long after
the implant has released all the dexamethasone.
TABLE-US-00003 TABLE 3 Improved (Decreased) Retinal Thickness as
Measured by Optical Coherence Tomography (OCT) 30 Days and 90 Days
after Placement of Intravitreal Implant Treatment Group Retinal
Thickness DEX PS DDS DEX PS DDS Observation (.mu.m) 350 .mu.g 700
.mu.g Group Change from Baseline -102.96 -157.11 12.73 at Day 30
Change from Baseline -63.08 -147.20 9.54 at Day 90
[0215] Improved (Decreased) Retinal Vessel Leakage
[0216] Categorical improvement in leakage of the retinal
vasculature, an anatomical measure of macular edema, was assessed
by fluorescein angiography at baseline, Day 30 and at Day 90.
Patients who had baseline and at least one follow-up evaluation
were included in the analysis. As shown by Table 4, LOCF
fluorescein leakage scores improved as compared to the observation
group for patients in both treatment groups by Day 30., By Day 90,
fluorescein leakage for both DEX PS DDS treatment groups was
significantly improved over the observation group (700 .mu.g;
p<0.001 and 350 .quadrature.g; p=0.001).
[0217] Thus, it was demonstrated that use of an implant according
to the method set forth herein permits a patients' retinal blood
vessel leakage to decrease and that this improvement can be
retained for a period of time long after the implant has released
all the dexamethasone.
TABLE-US-00004 TABLE 4 Improved (Decreased) Retinal Blood Vessel
Leakage as Measured by Fluorescein Angiography 30 Days and 90 Days
after Placement of Intravitreal Implant Improvement in Treatment
Group Maximum DEX PS DDS DEX PS DDS Observation Fluorescein Leakage
350 .mu.g 700 .mu.g Group Change from Baseline at Day 30 .gtoreq.2
levels better 17% 28% 6% .gtoreq.3 levels better 11% 22% 4% Change
from Baseline to Day 90 .gtoreq.2 levels better 20% 34% 4%
.gtoreq.3 levels better 16% 25% 1%
[0218] Improved (Decreased) Retinal Thickness (Fundus
Photography)
[0219] Categorical improvement in retinal thickness was also
assessed by fundus photography at baseline, Day 30 and at Day 90.
Patients who had baseline and at least one follow-up evaluation
were included in the analysis. As shown by Table 5, at Day 30,
retinal thickness scores for both DEX PS DDS treatment groups were
significantly improved over the observation group (700 .mu.g;
p<0.001 and 350 .quadrature.g; p=0.031) By Day 90, the 700 .mu.g
treatment group continued to show statistical significance in
improvement of LOCF retinal thickness scores (p<0.001).
[0220] Thus, it was demonstrated that use of an implant according
to the method set forth herein permits a patients' aberrant retinal
thickness to improve and that the patient's improved (decreased)
retinal thickness can be retained for a period of time long after
the implant has released all the dexamethasone.
TABLE-US-00005 TABLE 5 Improved (Decreased) Retinal Thickness as
Measured by Fundus Photography 30 Days and 90 Days after Placement
of Intravitreal Implant Treatment Group Improved Retinal DEX PS DDS
DEX PS DDS Observation Thickness 350 .mu.g 700 .mu.g Group Change
from Baseline at Day 30 .gtoreq.2 levels better 13% 23% 2%
.gtoreq.3 levels better 6% 14% 1% Change from Baseline at Day 90
.gtoreq.2 levels better 16% 30% 4% .gtoreq.3 levels better 10% 24%
2%
[0221] Intraocular Pressure
[0222] Intraocular pressure (IOP) was recorded on days 1, 7, 30,
60, 90 and the 180. Over the course of the study 22 events of
elevation in IOP .gtoreq.25 mm Hg were noted in 17 patients
receiving the 350 .mu.g treatment and 22 events in 15 patients
receiving the 700 .mu.g treatment. No event of elevation in IOP
.gtoreq.25 mmHg was noted in the observation group. Differences in
IOP of .gtoreq.25 mm Hg between the 700 .mu.g treatment group (n=7)
and the observation group were significant at the day 180 visit
only (p=0.014). No statistical difference was seen at any time
interval for the 350 .mu.g treatment group as compared to the
observation group.
[0223] Of the 7 patients with elevated IOP at day 180, one patient
had an ocular history of glaucoma in both eyes at the baseline
visit. A second patient did not receive medication and the elevated
IOP resolved the same day.
[0224] As shown by Table 6, increases of IOP .gtoreq.10 mm Hg from
baseline occurred in a small number of eyes in all three groups. At
no time was there a statistical difference between the 350 .mu.g
group and the observation group. When the 700 .mu.g treatment group
was compared to the observation group, statistical difference was
seen at Day 60 only (p=0.044).
[0225] Prior to the present invention is was believed that
intravitreal administration of a steroid would cause a much more
significant increase in intraocular pressure than was observed in
the present study. See e.g. Wingate R., et al., Intravitreal
triamcinolone and elevated intraocular pressure, Aust & New
Zea. J of Opthalmology 27(6):431-2, December 1999; Gillies M., et
al., Safety of an intravitreal injection of triamcinolone, Arch
Opthalmol vol 122, 336-340 March 2004, and; Jonas J. et al.,
Intraocular pressure after intravitreal injection of triamcinolone
acetonide, Br. J. Opthalmol 2003; 87: 24-27
TABLE-US-00006 TABLE 6 Summary of Change from Baseline to Follow-up
Visits in Intraocular Pressure .gtoreq.10 mm Hg Study Follow-up
Visit Group Day 1 Day 7 Day 30 Day 60 Day 90 Day 180 DEX PS DDS %
of patients with 5 2 2 2 2 2 350 .quadrature.g Increase in IOP over
baseline of >=10 mm Hg DEX PS DDS % of patients with 5 3 1 3 2 6
700 .quadrature.g Increase in IOP over baseline of >=10 mm Hg
Observation % of patients with 3 4 2 0 1 1 Group Increase in IOP
over baseline of >=10 mm Hg
[0226] Cataract Development
[0227] There was no significant difference in cataract development
between treatment groups at any time point. Over 60% of patients in
all three study groups had a cataract present at baseline. As shown
by Table 7 there was no significant new cases of cataract.
TABLE-US-00007 TABLE 7 New Cases of Cataract Observed During the
Study Number of New Cataracts by Type of Cataract Treatment Group
Cortical Nuclear Subcapsular 350 .mu.g DEX PS DDS (n = 100) 0 1 0
700 .mu.g DEX PS DDS (n = 101) 1 1 1 Observation Group (n = 105) 1
1 1
[0228] Prior to the present invention is was believed that
intravitreal administration of a steroid would cause a much more
significant increase in cataracts than was observed in the present
study. See e.g. Gillies M., et al., Safety of an intravitreal
injection of triamcinolone, Arch Opthalmol vol 122, 336-340 March
2004.
[0229] Implant Dissolution and Location
[0230] DEX PS DDS dissolution and location were monitored by slit
lamp examination at all visits over the course of the study. DDS
dissolution was quantified based on a scale of absent, trace
present, <25%, <50%, .ltoreq.100% or >100% present. No
differences were observed between the dissolution rate of the 350
.mu.g and the 700 .mu.g treatment groups. At the Day 180 visit,
68.1% of patients in the 350 .mu.g group and 65.3% of patients in
the 700 .quadrature.g group had no visible presence of residual DEX
PS DDS. Of the remaining patients, most had only trace to
.ltoreq.25% amounts of residual DEX PS DDS remaining by the Day 180
visit. There was no significant difference in the location of the
DEX PS DDS between the two treatment groups at any time during the
course of the study.
[0231] The DEX PS DDS was found to be stable upon placement. No
significant migration of the DEX PS DDS was noted for either the
350 .mu.g or 700 .mu.g treatment group. Categorical analysis across
all DEX PS DDS locations showed no significant difference at any
time interval using Fisher's Exact test.
[0232] To conclude the safety and efficacy of two doses of
Dexamethasone Posterior Segment Drug Delivery System (DEX PS DDS)
versus observation for the treatment of persistent macular edema
(PME) was tested in a Phase 2, prospective, randomized,
multicenter, dose-ranging, controlled clinical trial. A total of
315 patients, .gtoreq.15 years of age, with PME associated with
diabetic retinopathy, uveitis, branch retinal vein occlusion
(BRVO), central retinal vein occlusion (CRVO) or Irvine-Gass
Syndrome present for at least 90 days despite prior intervention
were enrolled in this 180-day study. Patients were randomized in a
1:1:1 ratio to one of three study groups: 700 .mu.g DEX PS DDS, 350
.mu.g DEX PS DDS or observation. The intent-to-treat (ITT)
population consisted of 306 patients who were balanced between the
three study groups in terms of patient sex, age, race, baseline
etiology and duration of initial onset and duration of persistent
macular edema.
Example 7
Extended Treatment of Ocular Conditions with Various Active
Agents
[0233] An implant can be formulated with various active agents
following the procedures in Examples 1 and 2. These implants can
provide an extended therapeutic treatment of an ocular condition,
that is a therapeutic affect during a period of time after release
of all of the active agent from the implant and during which there
is no longer a therapeutic amount of the active agent present at
the ocular site at which the implant was placed. Thus, an implant
can be prepared containing a non-steroidal anti-inflammatory agent,
such as ketoralac (available from Allergan, Irvine, Calif. as
ketoralac tromethamine ophthalmic solution, under the tradename
Acular). Thus, for example, a ketoralac extended therapeutic
treatment implant can be implanted into an ocular site (i.e. into
the vitreous) of a patient with an ocular condition for a desired
extended therapeutic effect. The ocular condition can be an
inflammatory condition such as uveitis or the patient can be
afflicted with one or more of the following afflictions: macular
degeneration (including non-exudative age related macular
degeneration and exudative age related macular degeneration);
choroidal neovascularization; acute macular neuroretinopathy;
macular edema (including cystoid macular edema and diabetic macular
edema); Behcet's disease, diabetic retinopathy (including
proliferative diabetic retinopathy); retinal arterial occlusive
disease; central retinal vein occlusion; uveitic retinal disease;
retinal detachment; retinopathy; an epiretinal membrane disorder;
branch retinal vein occlusion; anterior ischemic optic neuropathy;
non-retinopathy diabetic retinal dysfunction, retinitis pigmentosa
and glaucoma. The implant(s) can be inserted into the vitreous
using the procedure such as trocar implantation. The implant can
release a therapeutic amount of the active agent to provide and
retain a therapeutic effect for an extended period of time to
thereby treat a symptom of an ocular condition.
[0234] Such an implant to provide an extended therapeutic treatment
of an ocular condition can also be prepared containing a steroid,
such an anti-angiogenesis steroid, such as an anecortave, as the
active agent.
[0235] VEGF (Vascular Endothelial Growth Factor) (also known as
VEGF-A) is a growth factor which can stimulate vascular endothelial
cell growth, survival, and proliferation. VEGF is believed to play
a central role in the development of new blood vessels
(angiogenesis) and the survival of immature blood vessels (vascular
maintenance). Tumor expression of VEGF can lead to the development
and maintenance of a vascular network, which promotes tumor growth
and metastasis. Thus, increased VEGF expression correlates with
poor prognosis in many tumor types. Inhibition of VEGF can be an
anticancer therapy used alone or to complement current therapeutic
modalities (eg, radiation, chemotherapy, targeted biologic
therapies).
[0236] VEGF is believed to exert its effects by binding to and
activating two structurally related membrane receptor tyrosine
kinases, VEGF receptor-1 (VEGFR-1 or fit-1) and VEGFR-2 (flk-1 or
KDR), which are expressed by endothelial cells within the blood
vessel wall. VEGF may also interact with the structurally distinct
receptor neuropilin-1. Binding of VEGF to these receptors initiates
a signaling cascade, resulting in effects on gene expression and
cell survival, proliferation, and migration. VEGF is a member of a
family of structurally related proteins (see Table A below). These
proteins bind to a family of VEGFRs (VEGF receptors), thereby
stimulating various biologic processes. Placental growth factor
(PIGF) and VEGF-B bind primarily to VEGFR-1. PIGF modulates
angiogenesis and may also play a role in the inflammatory response.
VEGF-C and VEGF-D bind primarily to VEGFR-3 and stimulate
lymphangiogenesis rather than angiogenesis.
TABLE-US-00008 TABLE A VEGF Family Members Receptors Functions VEGF
(VEGF-A) VEGFR-1, VEGFR-2, Angiogenesis neuropilin-1 Vascular
maintenance VEGF-B VEGFR-1 Not established VEGF-C VEGF-R, VEGFR-3
Lymphangiogenesis VEGF-D VEGFR-2, VEGFR-3 Lymphangiogenesis VEGF-E
(viral factor) VEGFR-2 Angiogenesis PIGF VEGFR-1, neuropilin-1
Angiogenesis and inflammation
[0237] An extended therapeutic effect implant system to treat an
ocular condition can contain as active agent a compound with acts
to inhibit formation of VEGF or to inhibit the binding of VEGF to
its VERFR. The active agent can be, for example, ranibizumab
(rhuFab V2) (Genentech, South San Francisco, Calif.) and the
implant(s) can be made using the method of Example 1 or the method
of Example 2, but with use of ranibizumab as the active agent,
instead of dexamethasone. Ranibizumab is an anti-VEGF (vascular
endothelial growth factor) product which may have particular
utility for patients with macular degeneration, including the wet
form of age-related macular 10 degeneration. The implant can be
loaded with about 100-300 .mu.g of the ranibizumab
[0238] Pegaptanib is an aptamer that can selectively bind to and
neutralize VEGF and may have utility for treatment of, for example,
age-related macular degeneration and diabetic macular edema by
inhibiting abnormal blood vessel growth and by stabilizing or
reverse blood vessel leakage in the back of the eye resulting in
improved vision. An extended therapeutic treatment implant can be
made with of pegaptanib sodium (Macugen; Pfizer Inc, New York or
Eyetech Pharmaceuticals, New York) as the active agent by loading
about 1 mg to 3 mg of Macugen according to the Example 1 or 2
method.
[0239] The pegaptanib sodium extended release implant system can be
implanted into an ocular region or site (i.e. into the vitreous) of
a patient with an ocular condition for a desired extended
therapeutic effect.
[0240] An extended treatment bioerodible intraocular implant for
treating an ocular condition, such as an ocular tumor can also be
made as set forth in this Example using about 1 mg of the VEGF Trap
compound available from Regeneron, Tarrytown, new York.
[0241] An extended therapeutic treatment implant treat an ocular
condition can contain a beta-adrenergic receptor antagonist (i.e. a
"beta blocker) such as levobunolol, betaxolol, carteolol, timolol
hemihydrate and timolol. Timolol maleate is commonly used to treat
of open-angle glaucoma. Thus, an extended therapeutic treatment
bioerodible implant containing timolol maleate (available from
multiple different suppliers under the trade names Timoptic,
Timopol or Loptomit) as the active agent can be made using the
method of Example 1 or the method of Example 2, but with use of
timolol maleate instead of dexamethasone. Thus, about 50 .mu.g of
the timolol maleate can be loaded into each of the three implants
prepared according to the Example 1 or method.
[0242] The timolol extended release implant system can be implanted
into an ocular region or site (i.e. into the vitreous) of a patient
with an ocular condition for a desired extended therapeutic effect.
The ocular condition can be an inflammatory condition such as
uveitis or the patient can be afflicted with one or more of the
following afflictions: macular degeneration (including
non-exudative age related macular degeneration and exudative age
related macular degeneration); choroidal neovascularization; acute
macular neuroretinopathy; macular edema (including cystoid macular
edema and diabetic macular edema); Behcet's disease, diabetic
retinopathy (including proliferative diabetic retinopathy); retinal
arterial occlusive disease; central retinal vein occlusion; uveitic
retinal disease; retinal detachment; retinopathy; an epiretinal
membrane disorder; branch retinal vein occlusion; anterior ischemic
optic neuropathy; non-retinopathy diabetic retinal dysfunction,
retinitis pigmentosa and glaucoma.
[0243] An extended therapeutic treatment implant system can be used
to treat an ocular condition can contain a prostamide. Prostamides
are naturally occurring substances biosynthesized from anandamide
in a pathway that includes COX2. Bimatoprost (Lumigan) is a
synthetic prostamide analog chemically related to prostamide F.
Lumigan has been approved by the FDA for the reduction of elevated
intraocular pressure (IOP) in patients with open-angle glaucoma or
ocular hypertension who are intolerant of or insufficiently
responsive to other IOP-lowering medications. Lumigan is believed
to lower intraocular pressure by increasing the outflow of aqueous
humor.
[0244] Thus, an extended therapeutic treatment bioerodible implant
containing Lumigan (Allergan, Irvine, Calif.) as the active agent
can be made using the method of Example 1 or the method of Example
2, but with use of Lumigan instead of dexamethasone. Thus, about
100 .mu.g of Lumigan can be loaded into each of the three implants
prepared according to the Example 1 or 2 method.
[0245] The Lumigan extended therapeutic effect implant an be
implanted into an ocular region or site (i.e. into the vitreous) of
a patient with an ocular condition for a desired therapeutic
effect. The ocular condition can be an inflammatory condition such
as uveitis or the patient can be afflicted with one or more of the
following afflictions: macular degeneration (including
non-exudative age related macular degeneration and exudative age
related macular degeneration); choroidal neovascularization; acute
macular neuroretinopathy; macular edema (including cystoid macular
edema and diabetic macular edema); Behcet's disease, diabetic
retinopathy (including proliferative diabetic retinopathy); retinal
arterial occlusive disease; central retinal vein occlusion; uveitic
retinal disease; retinal detachment; retinopathy; an epiretinal
membrane disorder; branch retinal vein occlusion; anterior ischemic
optic neuropathy; non-retinopathy diabetic retinal dysfunction,
retinitis pigmentosa and glaucoma.
[0246] An extended therapeutic treatment implant an be used to
treat an ocular condition wherein the implant contains as the
active agent an alpha-2 adrenergic receptor agonist, such as
clonidine, apraclonidine, or brimonidine. Thus, an extended release
bioerodible implant system containing brimonidine (Allergan,
Irvine, Calif., as Alphagan or Alphagan P) as the active agent can
be made using the method of Example 1 or the method of Example 2,
but with use of Alphagan instead of dexamethasone. Thus, about 50
.mu.g of Alphagan can be loaded into an implant prepared according
to the Example 1 or 2 method.
[0247] The brimonidine extended therapeutic treatment implant can
be implanted into an ocular region or site (i.e. into the vitreous)
of a patient with an ocular condition for a desired therapeutic
effect. The ocular condition can be an inflammatory condition such
as uveitis or the patient can be afflicted with one or more of the
following afflictions: macular degeneration (including
non-exudative age related macular degeneration and exudative age
related macular degeneration); choroidal neovascularization; acute
macular neuroretinopathy; macular edema (including cystoid macular
edema and diabetic macular edema); Behcet's disease, diabetic
retinopathy (including proliferative diabetic retinopathy); retinal
arterial occlusive disease; central retinal vein occlusion; uveitic
retinal disease; retinal detachment; retinopathy; an epiretinal
membrane disorder; branch retinal vein occlusion; anterior ischemic
optic neuropathy; non-retinopathy diabetic retinal dysfunction,
retinitis pigmentosa and glaucoma.
[0248] An extended therapeutic effect implant used to treat an
ocular condition can contain a retinoid such as an ethyl
nicotinate, such as a tazarotene. Thus, an extended release
bioerodible implant system containing tazarotene (Allergan, Irvine,
Calif.) as the active agent can be made using the method of Example
1 or the method of Example 2, but with use of tazarotene instead of
dexamethasone. Thus, about 100 .mu.g to 300 .mu.g of tazarotene can
be loaded into each of the three implants prepared according to the
Example 1 or 2 method.
[0249] The tazarotene extended therapeutic treatment implant can be
implanted into an ocular region or site (i.e. into the vitreous) of
a patient with an ocular condition for a desired therapeutic
effect.
[0250] Generally, tyrosine kinase inhibitors are small molecule
inhibitors of growth factor signaling. Protein tyrosine kinases
(PTKs) comprise a large and diverse class of proteins having
enzymatic activity. The PTKs play an important role in the control
of cell growth and differentiation. For example, receptor tyrosine
kinase mediated signal transduction is initiated by extracellular
interaction with a specific growth factor (ligand), followed by
receptor dimerization, transient stimulation of the intrinsic
protein tyrosine kinase activity and phosphorylation. Binding sites
are thereby created for intracellular signal transduction molecules
and lead to the formation of complexes with a spectrum of
cytoplasmic signaling molecules that facilitate the appropriate
cellular response (e.g., cell division, metabolic homeostasis, and
responses to the extracellular microenvironment).
[0251] With respect to receptor tyrosine kinases, it has been shown
also that tyrosine phosphorylation sites function as high-affinity
binding sites for SH2 (src homology) domains of signaling
molecules. Several intracellular substrate proteins that associate
with receptor tyrosine kinases (RTKs) have been identified. They
may be divided into two principal groups: (1) substrates which have
a catalytic domain; and (2) substrates which lack such domain but
serve as adapters and associate with catalytically active
molecules. The specificity of the interactions between receptors or
proteins and SH2 domains of their substrates is determined by the
amino acid residues immediately surrounding the phosphorylated
tyrosine residue. Differences in the binding affinities between SH2
domains and the amino acid sequences surrounding the
phosphotyrosine residues on particular receptors are consistent
with the observed differences in their substrate phosphorylation
profiles. These observations suggest that the function of each
receptor tyrosine kinase is determined not only by its pattern of
expression and ligand availability but also by the array of
downstream signal transduction pathways that are activated by a
particular receptor. Thus, phosphorylation provides an important
regulatory step which determines the selectivity of signaling
pathways recruited by specific growth factor receptors, as well as
differentiation factor receptors.
[0252] Aberrant expression or mutations in the PTKs have been shown
to lead to either uncontrolled cell proliferation (e.g. malignant
tumor growth) or to defects in key developmental processes.
Consequently, the biomedical community has expended significant
resources to discover the specific biological role of members of
the PTK family, their function in differentiation processes, their
involvement in tumorigenesis and in other diseases, the biochemical
mechanisms underlying their signal transduction pathways activated
upon ligand stimulation and the development of novel drugs.
[0253] Tyrosine kinases can be of the receptor-type (having
extracellular, transmembrane and intracellular domains) or the
non-receptor type (being wholly intracellular). The RTKs comprise a
large family of transmembrane receptors with diverse biological
activities. The intrinsic function of RTKs is activated upon ligand
binding, which results in phosphorylation of the receptor and
multiple cellular substrates, and subsequently in a variety of
cellular responses.
[0254] At present, at least nineteen (19) distinct RTK subfamilies
have been identified. One RTK subfamily, designated the HER
subfamily, is believed to be comprised of EGFR, HER2, HER3 and
HER4. Ligands to the Her subfamily of receptors include epithelial
growth factor (EGF), TGF-.alpha., amphiregulin, HB-EGF,
betacellulin and heregulin.
[0255] A second family of RTKs, designated the insulin subfamily,
is comprised of the INS-R, the IGF-1R and the IR-R. A third family,
the "PDGF" subfamily includes the PDGF .alpha. and .beta.
receptors, CSFIR, c-kit and FLK-II. Another subfamily of RTKs,
identified as the FLK family, is believed to be comprised of the
Kinase insert Domain-Receptor fetal liver kinase-1 (KDR/FLK-1), the
fetal liver kinase 4 (FLK-4) and the fms-like tyrosine kinase 1
(fit-1). Each of these receptors was initially believed to be
receptors for hematopoietic growth factors. Two other subfamilies
of RTKs have been designated as the FGF receptor family (FGFR1,
FGFR2, FGFR3 and FGFR4) and the Met subfamily (c-met and Ron).
[0256] Because of the similarities between the PDGF and FLK
subfamilies, the two subfamilies are often considered together. The
known RTK subfamilies are identified in Plowman et al, 1994,
DN&P 7(6): 334-339, which is incorporated herein by
reference.
[0257] The non-receptor tyrosine kinases represent a collection of
cellular enzymes which lack extracellular and transmembrane
sequences. At present, over twenty-four individual non-receptor
tyrosine kinases, comprising eleven (11) subfamilies (Src, Frk,
Btk, Csk, Abl, Zap70, Fes/Fps, Fak, Jak, Ack and LIMK) have been
identified. At present, the Src subfamily of non-receptor tyrosine
kinases is comprised of the largest number of PTKs and include Src,
Yes, Fyn, Lyn, Lck, Blk, Hck, Fgr and Yrk. The Src subfamily of
enzymes has been linked to oncogenesis. A more detailed discussion
of non-receptor tyrosine kinases is provided in Bolen, 1993,
Oncogen 8: 2025-2031, which is incorporated herein by
reference.
[0258] Many of the tyrosine kinases, whether an RTK or non-receptor
tyrosine kinase, have been found to be involved in cellular
signaling pathways leading to cellular signal cascades leading to
pathogenic conditions, including cancer, psoriasis and hyper immune
response.
[0259] In view of the surmised importance of PTKs to the control,
regulation and modulation of cell proliferation the diseases and
disorders associated with abnormal cell proliferation, many
attempts have been made to identify receptor and non-receptor
tyrosine kinase "inhibitors" using a variety of approaches,
including the use of mutant ligands (U.S. Pat. No. 4,966,849),
soluble receptors and antibodies (PCT Application No. WO 94/10202;
Kendall & Thomas, 1994, Proc. Nat'l Acad. Sci. 90: 10705-09;
Kim, et al, 1993, Nature 362: 841-844), RNA ligands (Jellinek, et
al, Biochemistry 33: 10450-56); Takano, et al, 1993, Mol. Bio. Cell
4:358 A; Kinsella, et al, 1992, Exp. Cell Res. 199: 56-62; Wright,
et al, 1992, J. Cellular Phys. 152: 448-57) and tyrosine kinase
inhibitors (PCT Application Nos. WO 94/03427; WO 92/21660; WO
91/15495; WO 94/14808; U.S. Pat. No. 5,330,992; Mariani, et al,
1994, Proc. Am. Assoc. Cancer Res. 35: 2268).
[0260] An extended therapeutic treatment implant to treat an ocular
condition can contain a tyrosine kinase inhibitor (TKI) such as a
TKI set forth in published U.S. patent application 2004 00019098
(available from Allergan, Irvine, Calif.) as the active agent can
be made using the method of Example 1 or the method of Example 2,
but with use of a TKI instead of dexamethasone. Thus, about 100
.mu.g of a TKI can be loaded into each of the three implants
prepared according to the Example 1 or 2 method.
[0261] The TKI extended therapeutic effect implant an be implanted
into an ocular region or site (i.e. into the vitreous) of a patient
with an ocular condition for a desired extended therapeutic
effect.
[0262] It is believed that overstimulation of the
N-methyl-D-aspartate (NMDA) receptor by glutamate is implicated in
a variety of disorders. Memantine is an NMDA antagonist which can
be used to reduce neuronal damage mediated by the NMDA receptor
complex. Memantine is a available form Merz Pharmaceuticals,
Greensboro, N.C. under the trade name Axura. An extended release
implant system can be used to treat an ocular condition. The
implant can contain an NMDA antagonist such as memantine. Thus, an
extended therapeutic treatment bioerodible implant containing
memantine as the active agent can be made using the method of
Example 1 or the method of Example 2, but with use of memantine
instead of dexamethasone. Thus, about 400 .mu.g of memantine can be
loaded into each of the three implants prepared according to the
Example 1 or 2 method.
[0263] The memantine extended release implant system can be
implanted into an ocular region or site (i.e. into the vitreous) of
a patient with an ocular condition for a desired extended
therapeutic effect.
[0264] Certain estratropones have anti-angiogenesis,
anti-neoplastic and related useful therapeutic activities. An
extended therapeutic treatment implant can contain an estratropone
such as 2-methoxyestradiol (available form Entremed, Inc., of
Rockville, Md. under the tradename Panzem). Thus, an extended
therapeutic treatment bioerodible implant containing memantine as
the active agent can be made using the method of Example 1 or the
method of Example 2, but with use of 2-methoxyestradiol instead of
dexamethasone. 2-methoxyestradiol can be used as a small molecule
angiogenic inhibitor to block abnormal blood vessel formation in
the back of the eye. Thus, about 400 .mu.g of 2-methoxyestradiol
can be loaded into each of the three implants prepared according to
the Example 1 or 2 method.
[0265] The 2-methoxyestradiol extended release implant system can
be implanted into an ocular region or site (i.e. into the vitreous)
of a patient with an ocular condition for a desired extended
therapeutic effect.
[0266] Using the same methodology set forth in Examples 1 and 2,
additional extended therapeutic treatment implants can be prepared
wherein the active agent is, for example, an agent to treat
intravitreal hemorrhage (such as Vitrase, available from Ista
Pharmaceuticals), an antibiotic (such as cyclosporine, or
gatifloxacin, the former being available from Allergan, Irvine,
Calif. under the tradename Restasis and the later from Allergan
under the tradename Zymar), ofloxacin, an androgen, epinastine
(Elestat, Allergan, Irvine, Calif.), or with a combination of two
or more active agents (such as a combination in a single extended
release implant of a prostamide (i.e. brimatoprost) and a best
blocker (i.e. timolol) or a combination of an alpha 2 adrenergic
agonist (i.e. brimonidine) and a beta blocker, such as timolol) in
the same extended delivery system. A method using an implant within
the scope of the present invention can be used in conjunction with
a photodynamic therapy or laser procedure upon an eye tissue.
[0267] All references, articles, patents, applications and
publications set forth above are incorporated herein by reference
in their entireties.
[0268] Accordingly, the spirit and scope of the following claims
should not be limited to the descriptions of the preferred
embodiments set forth above
* * * * *