U.S. patent application number 14/804474 was filed with the patent office on 2015-11-19 for rehydratable pharmaceutical product.
This patent application is currently assigned to BIOCOMPATIBLES UK LIMITED. The applicant listed for this patent is BIOCOMPATIBLES UK LIMITED. Invention is credited to Rosemary PALMER, Sean WILLIS.
Application Number | 20150328160 14/804474 |
Document ID | / |
Family ID | 37400859 |
Filed Date | 2015-11-19 |
United States Patent
Application |
20150328160 |
Kind Code |
A1 |
WILLIS; Sean ; et
al. |
November 19, 2015 |
REHYDRATABLE PHARMACEUTICAL PRODUCT
Abstract
A pharmaceutical product comprising lyophilised polymer matrix
including a biologically active compound, of particular utility for
embolisation, having improved rehydration properties is packaged in
an airtight package under vacuum.
Inventors: |
WILLIS; Sean; (Surrey,
GB) ; PALMER; Rosemary; (Surrey, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
BIOCOMPATIBLES UK LIMITED |
Farnham |
|
GB |
|
|
Assignee: |
BIOCOMPATIBLES UK LIMITED
Farnham
GB
|
Family ID: |
37400859 |
Appl. No.: |
14/804474 |
Filed: |
July 21, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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12305048 |
Jan 8, 2009 |
9107833 |
|
|
PCT/EP2007/056282 |
Jun 22, 2007 |
|
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14804474 |
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Current U.S.
Class: |
424/499 ;
206/524.8; 424/501; 514/283; 514/34; 53/432 |
Current CPC
Class: |
A61K 9/0019 20130101;
A61P 35/00 20180101; A61J 1/1406 20130101; A61J 1/065 20130101;
B65D 81/2015 20130101; A61J 1/1412 20130101; A61P 7/04 20180101;
A61K 9/1682 20130101; A61K 31/704 20130101; B65B 31/027 20130101;
B65B 63/08 20130101; A61K 9/1676 20130101; A61K 9/19 20130101; A61K
9/10 20130101; A61K 31/4745 20130101; A61K 9/1641 20130101; B82Y
5/00 20130101; A61K 45/06 20130101 |
International
Class: |
A61K 9/19 20060101
A61K009/19; A61K 31/4745 20060101 A61K031/4745; A61K 9/16 20060101
A61K009/16; A61K 45/06 20060101 A61K045/06; B65D 81/20 20060101
B65D081/20; B65B 31/02 20060101 B65B031/02; B65B 63/08 20060101
B65B063/08; A61J 1/14 20060101 A61J001/14; A61J 1/06 20060101
A61J001/06; A61K 31/704 20060101 A61K031/704; A61K 9/10 20060101
A61K009/10 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 22, 2006 |
EP |
06253242.9 |
Claims
1. A method for formulating a dried packaged product suitable for
direct administration to an animal after rehydration to form a
suspension comprising: i) providing particles of polymer matrix
swollen with water and having absorbed therein a non-volatile
biologically active compound; ii) cooling the swollen articles from
step i) in a freezing step to a temperature below the freezing
point for water; iii) in a lyophilisation step subjecting the
cooled particles from step ii) to a reduced pressure at which ice
sublimes for a period during which at least a portion of the
absorbed ice sublimes and water vapour is removed; and iv) in a
packaging step, packaging the dried particles under reduced
pressure and into a package that is substantially airtight and has
an interior under vacuum to form packaged particles.
2. A method according to claim 1, in which the said package
comprises a vessel which is substantially rigid and has a mouth
closed by a stopper and in which the pressure inside the package is
less than 0.95 bar.
3. A method according to claim 3, in which the particles of swollen
polymer are contained in the vessel during the freezing and
lyophilisation steps and in which the stopper is fitted into the
mouth of the vessel in the packaging step.
4. A method according to claim 1, in which the temperature to which
the particles are cooled in the cooling step is less than
-20.degree. C.
5. A method according to claim 1, in which the lyophilisation step
is carried out at a temperature less than -20.degree. C.
6. A method according to claim 1, in which the pressure in the
lyophilisation step is reduced to less than 100 mbar for.
7. A method according to claim 1, in which the polymer is a
water-insoluble, pharmaceutically acceptable polymer.
8. A method according to claim 7, in which the polymer is
cross-linked.
9. A method according to claim 7, in which the polymer is based on
poly(vinyl alcohol).
10. A method according to claim 7, in which the polymer is formed
by polymerisation of ethylenically unsaturated monomers.
11. A method according to claim 1, in which the particle sizes are
selected such that upon rehydration in 0.9 wt % saline at room
temperature, the average particle size is in the range 40 to 2000
.mu.m.
12. A method according to claim 1, in which the particles are
substantially spherical in shape.
13. A method according to claim 1, in which the biologically active
compound is selected from anti-proliferatives, including
anti-neoplastics, anti-migratories, immunosuppressants, analgesics,
anti-inflammatories, anti-pyretics, anaesthetics and
anti-bacterials.
14. A method according to claim 13, in which the biologically
active is an anti-neoplastic agent selected from angiopeptin,
statins, such as sandostatin, azacitidine, bleomycin and bleomycin
sulphate, carboplatin, cisplatin, streptozoticin, capecitabine,
vinorelbine, cyclosporin, cytabanine, dacarbazine, anthracyclines
such as daunorubicin hydrochloride and doxorubicin hydrochloride,
fluorouracil, haropiridol, gemcitabine, ifosfamide, methotrexate,
mitoxantrone, banoxantrone, mitomycin, mustine hydrochloride,
lomustine, carmustine/BCNU, meclorethamine, vincristine,
vinblastine and cytosar/cytarabine, paclitaxel, docetaxel,
rapamycin and derivatives, such as tyrphostin, tacrolimus,
everolimus, biolimus, zotarolimus and RAD001,
tetradecylselenoacetic acid, tetradecyl thioacetic acid,
ethylisopropylamiloride, antithrombin, aggrastat, cilostazol,
clexane, clopidogrel, dipyridamole, persantine, integrillin,
abciximab, trapidil, matrix metalloproteinase inhibitors such as
batimastat and marimastat, VEGF, carvedilol, estradiol and other
estrogens, L-arginine, nitric oxide donors, probucol, quinaprilat,
thioctacid, telmisartan, zoledronate, and irinotecan.
15. A method of preparing a pharmaceutical suspension for
administration to an animal in which the product of a method
according to claim 1, optionally after a storage period of 1 day to
10 years, is rehydrated by adding to the package of dried product a
pharmaceutically acceptable sterile aqueous liquid, substantially
without allowing ingress of air, and, optionally, a contrast
medium, to form a suspension of swollen particles in the aqueous
liquid.
16. A method of treatment of an animal in which there is prepared a
pharmaceutical suspension for administration to an animal in which
the product of a method according to claim 1, optionally after a
storage period of 1 day to 10 years, is rehydrated by adding to the
package of dried product a pharmaceutically acceptable sterile
aqueous liquid, substantially without allowing ingress of air, and,
optionally, a contrast medium, to form a suspension of swollen
particles in the aqueous liquid and the suspension is administered
to an animal.
17. An airtight package containing, under vacuum, lyophilised
particles of water-swellable water-insoluble biocompatible polymer
into which is absorbed a pharmaceutically acceptable biologically
active compound, in which the particles are swellable in 0.9 wt %
saline at room temperature to sizes in the range 40 to 2000
.mu.m.
18. Package according to claim 17, in which the package is
rigid.
19. Package according to claim 18, in which the package is of glass
closed with an airtight closure, including a stopper penetrable by
hypodermic needle.
20. Package according to claim 17, in which the polymer is a
water-insoluble, pharmaceutically acceptable polymer.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 12/305,048, filed Jan. 8, 2009, now allowed,
which is a national stage entry of PCT/EP2007/056282, filed Jun.
22, 2007, which claims priority to EP application No. 0625324.9
filed Jun. 22, 2006. The entire disclosures of the prior
applications are considered part of the disclosure of the
accompanying continuation application, and are hereby incorporated
by reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to methods for formulating
storage stable and easily rehydratable dried pharmaceutical
compositions for administration to animals, especially for use as
chemo-embolic compositions.
[0003] Embolisation therapy involves the introduction of an agent
into the vasculature in order to bring about the deliberate
blockage of a particular vessel. This type of therapy is
particularly useful for blocking abnormal connections between
arteries and veins, such as arteriovenous malformations (AVMs), and
also for occluding vessels that feed certain hyper-vascularised
tumours, in order to starve the abnormal tissue and bring about its
necrosis and shrinkage. Examples of areas in which embolotherapy is
increasingly being used are for the treatment of malignant
hyper-vascular tumours such as hepatocellular carcinoma (HCC) and
the treatment of uterine fibroids.
[0004] In the case of HCC it may be desirable to treat the tumour
with an embolisation agent loaded with a chemotherapeutic agent. DC
bead is an embolisation bead that can be loaded with doxorubicin
prior to administration to a patient. It may be more convenient,
however, if the beads could be supplied to the interventional
radiologist with the doxorubicin already pre-loaded into the
embolic agents. This saves time in preparation, handling of toxic
drug and also the need to guess the amount of agent required for
the procedure.
[0005] Due to the fact that many drugs, such as doxorubicin, are
potentially unstable over time when in the hydrated form, an
embolic adduct with pre-loaded drug may be lyophilised or freeze
dried to remove excess water prior to terminal sterilization. The
lyophilisation process results in the formation of a free flowing
dry powder which is relatively stable during storage. This product
is described in WO 2004/071495 A1.
[0006] In WO 2004/071495 A1 the polymer matrix is a cross-linked
polyvinyl alcohol. Other particulate embolic materials are
available, for instance based on alginates, albumin, gelatin, other
synthetic polymers including PVA cross-linked with aldehydes,
polyacrylates, polylactic- and polyglycolic acids. These may be in
the form of irregular particles or, preferably, microspheres.
[0007] A number of other simple therapeutic compounds are being
investigated in combination with microspheres for the embolization
of other tumour types. Examples include irinotecan
(WO-A-2006027567) and ibuprofen (WO-A-2006013376). In addition,
newer drugs are becoming more complex in structure and there is a
move away from simple molecular entities to much more complex
entities which in some cases are of biological origin. These more
complex molecular entities will probably be more unstable than
corresponding simple molecular entities so the need for freeze
drying of microspheres loaded with these species will probably be
required to prolong their shelf-life.
[0008] One problem with freeze drying gels, e.g. hydrogels, or
macroporous microspheres is that air pockets develop within the
microspheres as the water is removed during the drying process. We
have identified the fact that the presence of these air pockets is
problematic when the dry beads are rehydrated. They can hinder the
rate of hydration of the beads since the air needs to be exchanged
with liquid for the bead to be fully hydrated. Since air is
relatively hydrophobic and the aqueous liquids used for rehydration
of the microspheres are hydrophilic, this process can be slow. In
some cases, we have found hydration is totally inhibited by the
presence of the air pockets within the micro spheres. One other
consequence of the presence of trapped air inside the microspheres
is the buoyancy of the microspheres is altered. Since the air is
less dense than the liquid for rehydration the beads tend to float.
This can be very problematic and can affect the potential to obtain
an adequate suspension of the beads when hydrated, in for instance,
a mixture of water and contrast agent. In order to deliver the
microspheres an adequate suspension is required in the hydration
medium for sufficient time to allow ease of handling and effective
delivery through a micro-catheter. Homogeneous delivery of
microspheres and suspending/contrast medium allows control of the
dose of microspheres and of active.
SUMMARY OF THE INVENTION
[0009] The present invention overcomes these problems of speed of
hydration and ineffective suspension and avoids the addition of
additional excipients to the particles.
[0010] According to the invention there is provided a new method
for formulating the dried product suitable for direct
administration into an animal after rehydration to form a
suspension comprising: [0011] i) a freezing step in which particles
of polymer matrix swollen with water and having absorbed therein a
non-volatile biologically active compound are cooled to a
temperature below the freezing point of water; [0012] ii) a
lyophilisation step in which the cooled particles from step i) are
subjected to a reduced pressure at which ice sublimes for a period
during which at least a portion of the absorbed ice sublimes and
water vapour is removed to form dried particles; and [0013] iii) a
packaging step in which the dried particles are packaged; [0014]
characterised in that the packaging step is carried out under
reduced pressure and the package containing the particles is
substantially airtight and has an interior under vacuum.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIGS. 1A, 1B, 1C, 1D and 1E are diagrammatic representations
of the apparatus in which the examples are carried out showing how
the vials are stopped without allowing ingress of air.
DETAILED DESCRIPTION OF THE INVENTION
[0016] The steps i) and ii) are generally carried out under the
same conditions as in general lyophilisation processes for
pharmaceuticals. It is convenient for further drying steps to be
included, for instance between steps ii) and iii). Such further
drying steps may be carried out to remove additional water and may
be carried out at a temperature above the freezing point of water
and at a reduced pressure, for instance at a pressure lower than
the pressure for which step i) is conducted. Suitable cycles are
known comprising a combination of cold low pressure steps, followed
by warmer, further reduced pressure steps, whereby water, including
physically bound water, is removed from the polymer matrix.
[0017] Suitable pressures under which the lyophilisation step is
carried out are in the range 0.01 mbar to 0.1 bar, preferably less
than 100 mbar often less than 10 mbar, e.g. less than 1 mbar often
0.02 mbar and upwards. Suitable temperatures for the cooling and
lyophilisation step are less than -10.degree. C., preferably less
than -15.degree. C., often less than -20.degree. C., for instance
down to -50.degree. C., preferably around -30.degree. C.
[0018] Suitable pressures at which a further drying step between
steps ii) and iii), are less than 0.2 mbar, preferably less than
0.1 bar, for instance down to 0.01 mbar, preferably about 0.05
mbar. Suitable temperatures are at least 0.degree. C., preferably
at least 25.degree. C., more preferably at least 60.degree. C.
[0019] Generally the temperatures and pressures are to be adapted
dependant upon the volumes, especially the depths of the container
of beads being treated. Shallow containers generally require less
time to be frozen and shorter low pressure cycles than deep
containers containing large quantities of materials. The freezing
step may be carried out for a period of at least 5 minutes, for
instance at least 10 minutes often an hour or more. The
lyophilisation step may be carried out for a period of at least one
hour, often overnight, for instance for a period of at least 8
hours or even more. The further drying step may be carried out over
a period of at least an hour preferably two hours or more.
[0020] Although it is possible to carry out the method of the
invention in bulk, with subsequent weighing and packaging in dosage
forms, all carried out under vacuum, it is most convenient for
steps i) and ii) or the method of the invention to be carried out
with the swollen particles already contained within the vessels in
which they are finally to be packaged. The vessels thus each
contain a single dose of particles with biologically active
compound. In such processes, the vessels are preferably formed of a
rigid material, and have a mouth which is stoppered in the
packaging step using a suitable airtight stopper. Suitable vessels
are formed of glass, or may be rigid airtight plastics which are
physically stable at the temperatures to which the material is
subjected during the method of the invention. Most conveniently the
method of the invention is carried out in an apparatus which is
capable simultaneously of carrying out the freeze-drying and
stoppering steps. Preferably substantially without allowing ingress
air, oxygen or other gas after step ii) and before step iii). A
suitable apparatus is commercially available under the trade name
Epsilon 1-6D freeze drier by Christ and Genesis freeze drier by
VirTis. Stoppers which are adequately airtight over useful storage
periods are made of, for instance, butyl rubber although other low
permeability rubbers which are stable at temperatures down to -30
or less .degree. C., may be used. It is particularly convenient for
the stoppers to be formed of a material which may be pierced with a
hypodermic needle, so that rehydrating liquid may be easily
injected into the stoppered vessels. During storage the pressure
inside the vessel may increase as air slowly permeates through the
stopper, but the permeability should be such that the pressure
inside the vessel is less than atmospheric after storage periods of
at least a month, preferably at least a year, for instance two
years or more.
[0021] The method of the invention is particularly suitable for
formulating compositions in which the polymer is a water-insoluble,
preferably but not limited to a substantially non-biodegradable,
pharmaceutically acceptable polymer. Since the starting material is
water-swollen, then the polymer must be water-swellable. At the
start of the method of the invention the polymer is preferably
swollen substantially to equilibrium in aqueous liquid. Generally
there is substantially no extra-particulate aqueous liquid, and the
method may involve a preliminary step in which a suspension of
swollen polymer particles in an aqueous liquid is subjected to an
initial drying step in which extra particulate liquid is removed,
for instance by decantation, filtration or centrifugation.
[0022] The polymer is preferably cross-linked, most preferably
covalently cross-linked, although ionically cross-linked polymers
may also be usefully formulated using the method of the invention.
Ionically cross-linked materials may comprise, for instance,
ionically charged polymer, cross-linked with counterionically
charged second polymer or, alternatively, with multivalent metal
ions.
[0023] It may be suitable to use polymers which are derived from
natural sources, such as albumin, alginate, gelatin, starch,
chitosan or collagen, all of which have been used as embolic
agents. Natural polymers or derivatives may be combined with
synthetic polymers, by blending, inter molecular cross-linking or
grafting. However, preferably the polymer is preferably
substantially free of naturally occurring polymer or
derivatives.
[0024] Preferably the polymer is based on a synthetic material, for
instance formed by polymerisation of ethylenically unsaturated
monomer, preferably in the presence of cross-linking monomer, for
instance macromer or di- or higher-functional cross-linking
monomers.
[0025] The ethylenically unsaturated monomers may include an ionic
(including zwitterionic) monomer.
[0026] Copolymers of hydroxyethyl methacrylate, acrylic acid and
cross-linking monomer, such as ethylene glycol dimethacrylate or
methylene bisacrylamide, as used for etafilcon A based contact
lenses may be used. Copolymers of
N-acryloyl-2-amino-2-hydroxymethyl-propane-1,3-diol and
N,N-bisacrylamide may also be used.
[0027] Other suitable polymers are cross-linked styrenic polymers,
e.g. with ionic substituents, of the type used as separation media
or as ion exchange media, and polyphosphazenes.
[0028] Another type of polymer which may be used to form the
water-swellable water-insoluble matrix is polyvinyl alcohol
cross-linked using aldehyde type cross-linking agents such as
glutaraldehyde. For such products, the polyvinyl alcohol (PVA) may
be rendered ionic or may be substantially non-ionic. For instance
the PVA may be rendered ionic by providing pendant ionic groups by
reacting a functional ionic group containing compound with the
hydroxyl groups. Examples of suitable functional groups for
reaction with the hydroxyl groups are acylating agents, such as
carboxylic acids or derivatives thereof, or other acidic groups
which may form esters. Suitable commercially available embolic
agents based on polyvinyl alcohol which may be used in the
invention are Ivalon.TM., Trufill.RTM., Contour SE.TM. and
Hepasphere.TM..
[0029] The invention is of particular value where the polymer
matrix is formed of a polyvinyl alcohol macromer, having more than
one ethylenically unsaturated pendant group per molecule, by
radical polymerisation of the ethylenic groups. Preferably the PVA
macromer is copolymerised with ethylenically unsaturated monomers
for instance including a nonionic and/or ionic monomer.
[0030] The PVA macromer may be formed, for instance, by providing
PVA polymer, of a suitable molecular weight such as in the range
1,000 to 500,000 D, preferably 10,000 to 100,000 D, with terminal
or mid-chain pendant vinylic or acrylic groups. Pendant acrylic
groups may be provided, for instance, by reacting acrylic or
methacrylic acid with PVA to form ester linkages through some of
the hydroxyl groups. Other methods for attaching vinylic groups
capable of polymerisation onto polyvinyl alcohol are described in,
for instance, U.S. Pat. No. 4,978,713 and, preferably, U.S. Pat.
Nos. 5,508,317 and 5,583,163. Thus the preferred macromer comprises
a backbone of polyvinyl alcohol to which is linked, via a cyclic
acetal linkage, an (alk)acrylaminoalkyl moiety. Example 1 of WO
2004/071495 describes the synthesis of an example of such a
macromer known by the approved named nelfilcon B which is useful in
this invention. Preferably the PVA macromers have about 2 to 20
pendant ethylenic groups per molecule, for instance 5 to 10.
[0031] Where PVA macromers are copolymerised with ethylenically
unsaturated monomers including an ionic monomer, the ionic monomer
preferably has the general formula I
Y.sup.1BQ
in which Y.sup.1 is selected from
##STR00001## [0032] CH.sub.2.dbd.C(R)--CH.sub.2--O--,
CH.sub.2.dbd.C(R)--CH.sub.2 OC(O)--, CH.sub.2.dbd.C(R)OC(O)--,
CH.sub.2.dbd.C(R)--O--, [0033]
CH.sub.2.dbd.C(R)CH.sub.2OC(O)N(R.sup.1)--,
R.sup.2OOCCR.dbd.CRC(O)--O--, RCH.dbd.CHC(O)O--, [0034]
RCH.dbd.C(COOR.sup.2)CH.sub.2--C(O)--O--,
##STR00002##
[0034] wherein:
[0035] R is hydrogen or a C.sub.1-C.sub.4 alkyl group;
[0036] R.sup.1 is a hydrogen or a C.sub.1-C.sub.4 alkyl group;
[0037] R.sup.2 is a hydrogen or a C.sub.1-C.sub.4 alkyl group or BQ
where B and Q are as defined below;
[0038] A is --O-- or --NR.sup.1--;
[0039] K.sup.1 is a group --(CH.sub.2),OC(O)--,
--(CH.sub.2),C(O)O--, --(CH.sub.2),OC(O)O--,
--(CH.sub.2).sub.rNR.sup.3--, --(CH.sub.2).sub.rNR.sup.3C(O)--,
--(CH.sub.2).sub.rC(O)NR.sup.3--,
--(CH.sub.2).sub.rNR.sup.3C(O)O--,
--(CH.sub.2).sub.rOC(O)NR.sup.3--,
--(CH.sub.2).sub.rNR.sup.3C(O)NR.sup.3-- (in which the groups
R.sup.3 are the same or different), --(CH.sub.2).sub.rO--,
--(CH.sub.2).sub.rSO.sup.3--, or, optionally in combination with
B.sup.1, a valence bond and r is from 1 to 12 and R.sup.3 is
hydrogen or a C.sub.1-C.sub.4 alkyl group;
[0040] B is a straight or branched alkanediyl, oxaalkylene,
alkanediyloxaalkanediyl, or alkanediyloligo (oxaalkanediyl) chain
optionally containing one or more fluorine atoms up to and
including perfluorinated chains or, if Q or Y.sup.1 contains a
terminal carbon atom bonded to B a valence bond; and
[0041] Q is an ionic group.
[0042] An anionic group Q may be, for instance, a carboxylate,
carbonate, sulphonate, sulphate, nitrate, phosphonate or phosphate
group. The monomer may be polymerised as the free acid or in salt
form. Preferably the pK.sub.a of the conjugate acid is less than
5.
[0043] A suitable cationic group Q is preferably a group
N.sup.+R.sup.4.sub.3, P.sup.+R.sup.5.sub.3 or S.sup.+R.sup.5.sub.2
in which the groups R.sup.4 are the same or different and are each
hydrogen, C.sub.1-C.sub.4-alkyl or aryl (preferably phenyl) or two
of the groups R.sup.4 together with the heteroatom to which they
are attached from a saturated or unsaturated heterocyclic ring
containing from 5 to 7 atoms the groups R.sup.5 are each OR.sup.4
or R.sup.4. Preferably the cationic group is permanently cationic,
that is each R.sup.4 is other than hydrogen. Preferably a cationic
group Q is N.sup.+R.sup.4.sub.3 in which each R.sup.4 is
C.sub.1-C.sub.4-alkyl, preferably methyl.
[0044] A zwitterionic group Q may have an overall charge, for
instance by having a divalent centre of anionic charge and
monovalent centre of cationic charge or vice-versa or by having two
centres of cationic charge and one centre of anionic charge or
vice-versa. Preferably, however, the zwitterion has no overall
charge and most preferably has a centre of monovalent cationic
charge and a centre of monovalent anionic charge.
[0045] Examples of zwitterionic groups which may be used as Q in
the present invention are disclosed in WO 00/29481 A1.
[0046] Where the ethylenically unsaturated monomer includes
zwitterionic monomer, for instance, this may increase the
hydrophilicity, lubricity, biocompatibility and/or
haemocompatibility of the particles. Suitable zwitterionic monomers
are described in our earlier publications WO 92/07885 A, WO
94/16748 A, WO 94/16749 A and WO 95/20407 A. Preferably a
zwitterionic monomer is 2-methacryloyloxy-2'-trimethylammonium
ethyl phosphate inner salt (MPC).
[0047] In the monomer of general formula I preferably Y.sup.1 is a
group CH.sub.2.dbd.CRCOA-- in which R is H or methyl, preferably
methyl, and in which A is preferably NH. B is preferably an
alkanediyl group of 1 to 12, preferably 2 to 6 carbon atoms. Such
monomers are acrylic monomers.
[0048] There may be included in the ethylenically unsaturated
monomer diluent monomer, for instance non-ionic monomer. Such a
monomer may be useful to control the pK.sub.a of the acid groups,
to control the hydrophilicity or hydrophobicity of the product, to
provide hydrophobic regions in the polymer, or merely to act as
inert diluent. Examples of non-ionic diluent monomer are, for
instance, alkyl (alk) acrylates and (alk) acrylamides, especially
such compounds having alkyl groups with 1 to 12 carbon atoms,
hydroxy, and di-hydroxy-substituted alkyl(alk) acrylates and -(alk)
acrylamides, vinyl lactams, styrene and other aromatic
monomers.
[0049] In the polymer matrix, where there is ionic group present
the level of ion is preferably in the range 0.1 to 10 meq g.sup.-1,
preferably at least 1.0 meq g.sup.-1.
[0050] Where PVA macromer is copolymerised with other ethylenically
unsaturated monomers, the weight ratio of PVA macromer to other
monomer is preferably in the range of 50:1 to 1:5, more preferably
in the range 20:1 to 1:2. In the ethylenically unsaturated monomer
the ionic monomer is preferably present in an amount in the range
10 to 100 mole %, preferably at least 25 mole %.
[0051] The polymer may be formed into particles in several ways.
For instance, the cross-linked polymer may be made as a bulk
material, for instance in the form of a sheet or a block, and
subsequently be comminuted to the desired size. Alternatively, the
cross-linked polymer may be formed as such in particulate form, for
instance by polymerising in droplets of monomer in a dispersed
phase in a continuous immiscible carrier. Examples of suitable
water-in-oil polymerisations to produce particles having the
desired size, when swollen, are known. For instance U.S. Pat. No.
4,224,427 describes processes for forming uniform spherical beads
(microspheres) of up to 5 mm in diameter, by dispersing
water-soluble monomers into a continuous solvent phase, in a
presence of suspending agents. Stabilisers and surfactants may be
present to provide control over the size of the dispersed phase
particles. After polymerisation, the cross-linked microspheres are
recovered by known means, and washed and optionally sterilised.
Preferably the particles, e.g. microspheres, are swollen in an
aqueous liquid, and classified according to their size.
[0052] The method of the invention is of particular utility where
the rehydrated material is to be used as an embolic agent. The
particles are preferably microspheres, that is are formed of
substantially spherical or spheroidal particles. For embolic
agents, such particles are generally separated into size fractions,
whereby a surgeon may select microspheres of a size suited to
embolise the vessels desired to be blocked in the method of
treatment. For embolic materials, the particles generally have
average diameter in the range 40 to 2000 .mu.m, more preferably in
the range 100 to 1500 .mu.m. Preferably the particles have sizes
such that they fall in a nominal range around 200 .mu.m to 300
.mu.m in width. Suitable size fractions have nominal sizes in the
range 100 to 300, 300 to 500, 500 to 700, 700 to 900, 900 to 1200
.mu.m. The particle sizes may be determined in the invention at
various stages of the method. For instance the particle sizes may
be determined on the swollen particles used as the starting
materials for step i). Alternatively the particle sizes may be
measured on the rehydrated products of the method of the
invention.
[0053] Preferably the method of the invention comprises preliminary
loading steps in which particles of non-loaded polymer are loaded
with the biologically active compound. In such a method, the
non-loaded polymer particles generally have sizes in the range
defined above, when swollen to equilibrium at room temperature, in
0.9 wt % NaCl. The invention, as indicated above, is of particular
value where the particles are to be rehydrated to form an aqueous
suspension which is ultimately to be used as by direct
administration to an animal, for instance by direct injection into
a tumour or other target for local administration of the active. A
preferred use is as an embolic material. Of particular utility,
embolic materials are utilised to embolise solid tumours,
particularly malignant tumours although they may also be of use to
embolise benign tumours such as uterine fibroids. Biologically
active materials are preferably anti-tumour compounds, especially
compounds which are unstable in the presence of water or other
solvents. The invention is of particular value where the
biologically active compound is an anti-neoplastic or often
anti-proliferation, anti-migratory, immunosuppressant, analgesic,
anti-inflammatory, anti-pyretic, anti-bacterial or anaesthetic
agent.
[0054] The invention is of particular value for formulating
anti-neoplastics and immunosuppressants, such as angiopeptin, and
statins, such as sandostatin. Other suitable drugs include
azacitidine, bleomycin and bleomycin sulphate, carboplatin,
cisplatin, streptozoticin, capecitabine, vinorelbine, cyclosporin,
cytabanine, decarbazine, anthracyclines such as daunorubicin,
doxorubicin, epirubicin, mitoxantrone and banoxantrone. Other
suitable chemotherapeutics include fluorouracil, gemcitabine,
ifosfamide, methotrexate, mitomycin, mustine hydrochloride,
lomustine, carmustine/BCNU, meclorethamine, vincristine,
vinblastine, cytosar/cytarabine, peclitaxel, docetaxel, rapamycin
and derivatives, such as tacrolimus, everolimus, biolimus,
zotarolimus, and RAD001. Other suitable drugs include tyrphostin,
tetradecylselenoacetic acid, tetradecylthioacetic acid,
ethylisopropylamiloride, antithrombin, aggrastat, cilostazol,
clexane, clopidogrel, dipyridamole, persantine, integrillin,
abciximab, trapidil, VEGF, carredilol, estradiol and other
estrogens, L-arginine, nitric oxide donors, probucol, quinaprilat,
thioctacid, telmisartan, zoledronate and matrix metalloproteinase
inhibitors such as batimastat and marimastat.
[0055] Another class of compounds for which the invention is of
utility include analgesics, anti-inflammatories, and anti-pyretics,
such as Codeine sulphate, Diamorphine hydrochloride, fentanyl,
hydromorphone hydrochloride, indomethacin, morphine hydrochloride
and pethidine hydrochloride.
[0056] The invention may also be of utility for formulating
anti-bacterials, for instance which may be administered into the
arteriovenous system and/or may be administered in
extended/controlled release formulations comprising polymer matrix
formulations. Examples of such anti-bacterials are ampicillin,
benzyl-penicillin, ceftazidime, ceftriaxone sodium, gemtamicin
sulphate, tetracycline and vancomycin hydrochloride.
[0057] The method of loading the biologically active compound into
the polymer matrix to form the starting material for step i) of the
invention is selected according to the solubility of the active in
solvents compatible with the polymer matrix and/or the swellability
of the polymer in such solvents. For instance, in one preferred
combination of components, the polymer is generally ionically
charged, and is loaded by an ion-exchange type process with
counterionically charged active compound. Where the active is
doxorubicin hydrochloride, for instance, which is cationically
charged, the polymer matrix is preferably anionically charged.
[0058] According to a preferred aspect of the invention the
therapeutic active used in the present invention is an
anthracycline compound, which comprises an anthraquinone group to
which is attached an amine sugar. The amino group on the sugar is
believed to associate with anionic groups in the polymer matrix, to
allow high levels of loading and controlled delivery after
administration. Alternatively the amine groups can be pendant
groups on the anthracycline ring as for mitoxantrone and
banoxantrone.
[0059] Examples of suitable anthracyclines have the general formula
II
##STR00003##
[0060] Further a polymer matrix which allows good loading levels
and release is an anionic poly (vinyl alcohol) based material,
preferably formed by copolymerising the PVA macromer described
above with an ionic monomer of the general formula I in which Q is
an anionic group whose conjugate acid preferably has a pK.sub.a of
5 or less.
[0061] We have found that doxorubicin, which has been thoroughly
tested for efficacy on various tumours, has particularly
interesting loading and release characteristics. The drug appears
to have a particular affinity for poly(vinyl
alcohol-graft-acrylamido propane sulphonic acid), so that high
levels of doxorubicin are capable of incorporation into the
polymer, and release over many days.
[0062] According to another preferred embodiment the pharmaceutical
active is a camptothecin preferably a cationically charged
camptothecin used in combination with an ionically charged polymer.
Examples of such camptothecins have general formula III
##STR00004##
in which R.sup.10 is H, lower C.sub.(1-16)alkyl, optionally
substituted by a hydroxyl amine, alkoxy, halogen, acyl or acyloxy
group or halogen; and
[0063] R.sup.9 is chlorine or NR.sup.11R.sup.12 where R.sup.11 and
R.sup.12 are the same or different and each represent a hydrogen
atom, a substituted or unsubstituted C.sub.1-4 alkyl group or a
substituted or unsubstituted carbocyclic or heterocyclic group, or
R.sup.11 and R.sup.12 together with the nitrogen atom to which they
are attached form an optionally substituted heterocyclic ring which
may be interrupted by --O--, --S-- or >NR.sup.13 in which
R.sup.13 is a hydrogen atom, a substituted or unsubstituted
C.sub.1-4 alkyl group or a substituted or unsubstituted phenyl
group;
[0064] and wherein the grouping --O--CO--R.sup.9 is bonded to a
carbon atom located in any of the 9, 10 or 11 positions in the A
ring of the camptothecin compound, including salts thereof.
[0065] Preferably R.sup.9 is NR.sup.11 R.sup.12 in which R.sup.11
and R.sup.12 together with the nitrogen atom from an optionally
substituted heterocyclic ring. Most preferably R.sup.9 is
##STR00005##
[0066] Preferably R.sup.9 is substituted at the 10 position in the
camptothecin. Preferably R.sup.10 is ethyl.
[0067] The therapeutic active may be incorporated into the polymer
matrix by a variety of techniques. In one method, the therapeutic
active may be mixed with a precursor of the polymer, for instance a
monomer or macromer mixture or a cross-linkable polymer and
cross-linker mixture, prior to polymerising or cross-linking.
Alternatively, the active may be loaded into the polymer after it
has been cross-linked. For instance, particulate dried polymer may
be swollen in a solution of therapeutic active, preferably in
water, optionally with subsequent removal of non-absorbed agent
and/or evaporation of solvent. A solution of the active, in an
organic solvent such as an alcohol, or, more preferably, in water,
may be sprayed onto a moving bed of particles, whereby drug is
absorbed into the body of the particles with simultaneous solvent
removal. Most conveniently, we have found that it is possible
merely to contact swollen particles suspended in a continuous
liquid vehicle, such as water, with a solution of drug, over an
extended period, whereby drug becomes absorbed into the body of the
particles. This is believed to be analogous to a cation exchange
type process. The swelling vehicle may subsequently be removed or,
conveniently, may be retained with the particles as part of the
product for subsequent use as an embolic agent.
[0068] The drug loaded particles are then recovered from excess
loading solution or solvent and subjected to the above described
drying and packaging process.
[0069] The present invention comprises further a method preparing a
pharmaceutically acceptable suspension for administration to an
animal in which the product of the method of the invention defined
above is rehydrated by adding to the package of dried product a
pharmaceutically acceptable sterile aqueous liquid and, optionally,
a contrast medium, to form a suspension of swollen particles in a
continuous aqueous liquid.
[0070] The pharmaceutically acceptable sterile aqueous liquid is,
for instance, physiological saline, deionised water or, preferably,
phosphate buffered saline. Preferably the sterile aqueous liquid is
added directly into the airtight package by puncturing this with a
hypodermic needle through which the liquid is directed without
allowing ingress of gases, such as air or oxygen. Once the aqueous
rehydrating liquid and particles have formed a stable suspension,
this is preferably combined with contrast medium and mixed, to form
a suspension ready for administration to a patient.
[0071] There is also provided in the invention a method of
treatment of an animal in which the suspension formed in the
preceding paragraph is administered to an animal, preferably by
administration into an artery to embolise blood vessels, preferably
to embolise a solid tumour.
[0072] According to the invention there is also provided a new
airtight package containing, under vacuum, lyophilised particles of
water-swellable water-insoluble biocompatible polymer into which is
absorbed a pharmaceutically acceptable biologically active
compound, in which the particles are swellable in 0.9 wt % saline
at room temperature to sizes in the range 40 to 2000 .mu.m.
[0073] In this aspect of the invention the polymer and biologically
active compound have the preferred properties defined above in
connection with the first aspect of the invention.
[0074] The invention is illustrated further in the accompanying
examples.
Example 1
Microsphere Production
[0075] The spheres are synthesised by a method of suspension
polymerisation in which an aqueous phase comprising a solution
(about 700 g) containing a PVA macromer, nelfilicon A, (around 80
g), 2-acrylamido-2-methyl propane sulphonate sodium salt (70 g) and
potassium persulphate initiator (around 5 g) is suspended in an
organic phase of butyl acetate (31) and 5 g cellulose acetate
butyrate (solution in ethyl acetate) in a stirred reactor. By
employing rapid mixing the aqueous phase can be dispersed to form
droplets, the size and stability of which can be controlled by
factors such as stirring rates, viscosity, ratio of aqueous/organic
phase. Polymerisation of the dispersed monomer/macromer solution is
initiated by the addition of TMEDA and raising the temperature to
over 50.degree. C. for several hours under nitrogen. After cooling
to room temperature the product is purified by removing the butyl
acetate by filtration followed by washing steps with solvents,
vacuum dried to remove solvents then the microspheres are
equilibrated at 60.degree. C. in water to fully re-hydrate. The
spheres are sieved using a 316 L stainless steel vortisieve unit
(MM Industries, Salem Ohio) with stainless steel sieving trays with
mesh sizes ranging from 32 to 1200 .mu.m including sizes about 100
.mu.m, 300 .mu.m, 500 .mu.m, 700 .mu.m and 900 .mu.m. Spheres
collected in the 32 .mu.m sieve are discarded.
[0076] Drug Loading
[0077] For each size of microsphere used, 0.5 ml was transferred in
to 2, 1 ml syringes, one for drug take up and the second to act as
a control. The sizes chosen for the experiment were, 100-300 .mu.m,
300-500 .mu.m, 500-700 .mu.m and 850-1000 .mu.m. Additionally a
further 3 syringes of the 500-700 .mu.m were prepared in order to
validate the procedure. 11, 10 ml glass vials were covered in foil,
to prevent degradation of the doxorubicin by light for the duration
of the experiment. A standard curve was created. Using the 80 ml,
20 mg/ml drug solution, the following concentrations were prepared
and their absorbances (at 483 nm) measured: 100 .mu.g/ml, 50
.mu.g/ml, 25 .mu.g/ml, 12.5 .mu.g/ml, 6.25 .mu.g/ml and 3.125
.mu.g/ml. The resulting absorbances were plotted on a graph and the
equation of the line used to calculate the concentration of drug
that was uptaken by the beads in the experiment. Four of the vials
were filled with 5 ml of distilled water (ROMIL) to be used as
controls when the beads were added. To the remaining 7 vials were
added 5 ml of the drug solution at the desired concentration. The
starting absorbance and therefore concentration of the solution was
already known from the preparation of the standard curve. (In order
to measure the absorbance of the 20 5 mg/ml solution it was
necessary to dilute it 200 times, using the concentration 100
.mu.g/ml. This 1:200 dilution was carried through for the duration
of measuring the uptake of the solution by the beads.) The
stopwatch was started as soon as the first set of microspheres were
added to the first drug containing vial, microspheres were added to
each of the remaining 6 vials working from smallest to largest.
Once sealed using the caps they were placed on the rotary mixer.
The process was repeated for the control samples. The absorbances
were measured in the same order as the vials were set up at time
intervals of 0.167 hr (10 min), 0.5 hr, 1 hr, 2 hr, 24 hrs and 96
hrs. From the data the amount of drug (in mg) per 1 ml of
microspheres and the % uptake of drug by 1 ml of microspheres could
be calculated.
[0078] Epsilon 1-6D freeze dryer is used in the next step of the
production of 100-300, 300-500, 500-700 and 700-900 .mu.m
(1.5.+-.0.1 ml) preloaded with 37.5 mg doxorubicin per vial. The
vials are type 1 tubular neutral glass 10 ml vials and the bungs
are butyl rubber igloo lyophilisation stoppers. The lyophilisation
program has been designed to operate when fully loaded with 345
vials of microspheres.
[0079] Epsilon 1-6D freeze dryer with Lyo Screen Control (LSC)
panel and Pfeiffer DUO 10 Rotary Vane Vacuum pump. The apparatus is
controlled by Lyolog LL-1 documentation software.
[0080] The Epsilon 1-6D is a pilot scale freeze dryer. The system
consists of a chamber with three liquid controlled cooled/heated
shelves with a temperature range of -40 to 80.degree. C. on which
samples are frozen. The ice condenser, whose minimum temperature is
-60.degree. C., is located in an adjacent chamber separated by an
intermediate valve. The shelves and ice condenser are cooled using
two cooling machines. The chamber pressure is achieved using a
Pfeiffer DUO 10 rotary vane vacuum pump.
[0081] The Epsilon 1-6D can lyophilise a maximum of 345 vials (10
ml) per cycle, i.e. with 115 vials per shelf.
[0082] The microspheres are lyophilised by freezing at about
-30.degree. C. without a vacuum, at least 1 h, then reducing the
pressure gradually over a period of about half an hour to a
pressure of in the range 0.35-0.40 mbar, while allowing the
temperature to rise to about -20.degree. C. and holding the
conditions at this temperature and pressure overnight, followed by
raising the temperature to room temperature for a period of about
1-2 hours at the same time pressure, followed by a period at room
temperature with the pressure reduced to about 0.05 mbar, to a
total cycle time of 24 hours.
[0083] At the end of the cycle and substantially without allowing
ingress of air the vials are stoppered under vacuum by turning the
vial closing mechanism that lowers the shelves to stopper the vials
on the shelf beneath. The chamber is then aerated to allow the
chamber to reach atmospheric pressure. The shelves are then
returned to their original position and the chamber opened.
[0084] As a control, the process is repeated but the chamber is
allowed to equilibrate to atmospheric pressure by allowing ingress
of air to atmospheric pressure prior to the vials being
stoppered.
[0085] The products of the method of the invention loaded with
doxorubicin (typically 25 to 40 mg drug per ml bead) and of the
comparison method are then rehydrated by injection of 3 ml of water
and 3 ml contrast agent (e.g. Lipiodiol) using a conventional
hypodermic needle attached to a syringe to pierce the stopper. The
vials are shaken for 3 minutes manually or using a mechanical
shaker. The method of the invention thus allows faster rehydration
and easier handling both of which enable more control of dosage
which are all of high importance for a surgeon wishing to
immediately administer the suspension to a patient undergoing
surgery. Even after longer periods of shaking, the control
microspheres include a fraction which float on the surface.
[0086] The method of the invention thus allows easier handling,
improved dosage control, and faster rehydration, all of high
importance for a surgeon or interventional radiologist wishing to
immediately administer the suspension to a patient undergoing
surgery.
Example 2
[0087] The beads produced as in Example 1 are loaded with
irinotecan loaded at a level of around 50 mg drug per ml beads. The
lyophilisation cycle was the same as that used in example 1. The
beads could easily be rehydrated upon addition of saline to the
container under lower than atmospheric pressure, the beads quickly
sinking and being capable of forming a homogeneous suspension.
Example 3
[0088] Alginate microspheres are formed as follows. An aqueous
solution of high G alginate (recovered as described in WO 00/09566
A) is cross-linked by spraying droplets of the 2% solution into a
precipitation bath comprising a solution of calcium ions, followed
by collection of the formed microspheres. The micro spheres have an
average size of 215 .mu.m (standard deviations 3 .mu.m). After
cleaning, 0.2 ml of 2% alginate microsphere suspension is
transferred into a vial. Excess liquid is decanted, then 1.39 mls
of 10.07 mg per ml aqueous doxorubicin solution is added to the
microspheres. The mixture is shaken overnight. After this time, the
loading capacity is determined by measuring the concentration of a
portion of decanted excess loading solution. This reveals a loading
capacity of around 50 to 60 mg doxorubicin per ml of bead
suspension. Excess loading solution is removed and the bead slurry
subjected to freeze drying in the vial.
[0089] The freeze drying cycle is substantially as described in
example 1. At the end of the cycle the vials are stoppered under
the final vacuum.
[0090] When resuspended in 0.9 wt % saline, the beads rehydrated
rapidly, and sank in the suspension.
* * * * *