U.S. patent application number 10/545409 was filed with the patent office on 2006-07-27 for medicinal composition for ophthal use containing acetylated hyaluronic acid.
Invention is credited to Takashi Oka, Norio Ueno.
Application Number | 20060166930 10/545409 |
Document ID | / |
Family ID | 32923361 |
Filed Date | 2006-07-27 |
United States Patent
Application |
20060166930 |
Kind Code |
A1 |
Ueno; Norio ; et
al. |
July 27, 2006 |
Medicinal composition for ophthal use containing acetylated
hyaluronic acid
Abstract
The present invention provides an ophthalmic pharmaceutical
composition containing acetylated hyaluronic acid and a
pharmacologically acceptable carrier. Preferably, the average
molecular weight of the acetylated hyaluronic acid is 10,000 to
1,000,000, and the acetyl group substitution number is from 2.0 to
4.0. In a preferred embodiment, this ophthalmic pharmaceutical
composition is used in the treatment or prevention of dry eye, and
in an even more preferred embodiment it is a dry-eye
instillation.
Inventors: |
Ueno; Norio; (Kanagawa,
JP) ; Oka; Takashi; (Kanagawa, JP) |
Correspondence
Address: |
SNIDER & ASSOCIATES
P. O. BOX 27613
WASHINGTON
DC
20038-7613
US
|
Family ID: |
32923361 |
Appl. No.: |
10/545409 |
Filed: |
February 27, 2004 |
PCT Filed: |
February 27, 2004 |
PCT NO: |
PCT/JP04/02365 |
371 Date: |
August 12, 2005 |
Current U.S.
Class: |
514/54 |
Current CPC
Class: |
C08B 37/0072 20130101;
A61K 31/728 20130101; A61P 27/02 20180101; A61P 27/04 20180101 |
Class at
Publication: |
514/054 |
International
Class: |
A61K 31/728 20060101
A61K031/728 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 27, 2003 |
JP |
2003-051161 |
Claims
1. An ophthalmic pharmaceutical composition comprising acetylated
hyaluronic acid and a pharmacologically acceptable carrier.
2. The ophthalmic pharmaceutical composition according to claim 1,
wherein the average molecular weight of the acetylated hyaluronic
acid is from 10,000 to 1,000,000, and the acetyl group substitution
number is 2.0 to 4.0
3. The ophthalmic pharmaceutical composition according to claim 1,
which is used for the treatment of dry eye.
4. The ophthalmic pharmaceutical composition according to claim 3,
which is a dry-eye instillation.
5. The ophthalmic pharmaceutical composition according to claim 2,
which is used for the treatment of dry eye.
Description
[0001] This application claims the priority of Japanese application
No. 2003-051161 filed on 27.sup.th Feb. 2003, which is incorporated
by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to an ophthalmic
pharmaceutical composition that contains acetylated hyaluronic acid
and has excellent moisture retention.
BACKGROUND OF ART
[0003] The number of patients or pseudo-patients complaining of dry
eye (dryness of the eyes) is expected to continue to climb as our
society ages and as people increasingly strain their eyes by
watching television and using office equipment such as word
processors and personal computers. The cause of dry eye is a
reduction in lacrimal quantity or a qualitative change in the
components thereof, and this disorder can result in scratching or
other damage when the surface of the eye becomes dry. Symptoms
include eye pain or fatigue, increased blinking, and bloodshot
eyes. Further, bacteria may enter through a scratch and cause
infection, and if the scratch is deep enough it can even affect the
vision of the person. In addition to eyestrain, causes of dry eye
include Sjogren's syndrome, Stevens-Johnson syndrome, burns and
injury to the eye, and side effects of hypotensive drugs,
tranquilizers, eyedrops for treating glaucoma, and other such
drugs.
[0004] Eyedrops are an effective way to treat dry eye, and dry-eye
treatment drugs whose main component is hyaluronic acid are
currently attracting much attention and are widely used. Hyaluronic
acid is a biologically derived macromolecular substance, has
extremely high water retention and characteristic properties such
as a high viscoelasticity, a good thickening property, and a good
thread-forming, ability, and has been used as a humectant in
topical agents for treating various kinds of skin problems and so
forth. In the case of dry eye caused by Sjogren's syndrome, in
which dryness is seen over the entire body, the application of
eyedrops containing hyaluronic acid is effective all by itself, but
when the symptoms are severe, hyaluronic acid-containing eyedrops
alone may not provide a sufficient effect, and it is sometimes
necessary for the treatment to entail tear duct blockage by means
of a tear duct plug. Also, hyaluronic acid has a relatively short
residence time on the cornea, so the effect of hyaluronic acid
eyedrops lasts only about 2 or 3 hours, which means that the
patient must apply the drops more frequently (such as 5 to 10 times
a day). There is therefore a need for an ophthalmic pharmaceutical
composition that would provide a long-lasting humectant effect, and
therefore require fewer applications and improve the QOL (quality
of life) of the patient.
[0005] Japanese Laid-Open Patent Application S62-68402 discloses a
derivative of hyaluronic acid, namely, a hyaluronic acid that has
undergone partial esterification of its carboxyl groups, and
suggests that this derivative is effective as a drug carrier.
However, it has yet to be confirmed that an ophthalmic preparation
containing this carboxyl group partially esterified hyaluronic acid
derivative as a carrier is effective in pharmaceutical compositions
used for dry eye, which must provide a long-lasting humectant
effect.
DISCLOSURE OF THE INVENTION
[0006] It is an object of the present invention to provide
pharmaceutical composition for dry eye, which remains on the cornea
and exhibits a humectant effect for a longer period.
[0007] The inventors were surprised to learn that when an
acetylated derivative of hyaluronic acid is used as an ophthalmic
pharmaceutical composition, this derivative stays longer than
hyaluronic acid on a soft contact lens, which is a model for the
corneal epithelium. Thus, an ophthalmic pharmaceutical composition
that contains acetylated hyaluronic acid was found to exhibit a
humectant effect over a longer period than an ophthalmic
pharmaceutical composition containing just hyaluronic acid.
[0008] Therefore, the present invention provides an ophthalmic
pharmaceutical composition containing acetylated hyaluronic acid
and a pharmacologically acceptable carrier. Preferably, the average
molecular weight of the acetylated hyaluronic acid is from 10,000
to 1,000,000, and the acetyl group substitution number is 2.5 to
4.0, even more preferably the average molecular weight of the
acetylated hyaluronic acid is approximately 100,000 and the acetyl
group substitution number is approximately 3.3. In a preferred
aspect, this ophthalmic pharmaceutical composition is used for the
treatment or prevention of dry eye, and in an even more preferred
aspect, it is a dry-eye instillation.
BEST MODE FOR CARRYING OUT THE INVENTION
[0009] When applied to the eye, the acetylated hyaluronic
acid-containing ophthalmic pharmaceutical composition pertaining to
the present invention exhibits better moisture retention than an
ophthalmic pharmaceutical composition containing hyaluronic acid.
The corneal epithelium of the eye is composed of about five cell
layers, and it some ways is similar to the horny layer of the skin,
but the cellular surface of the topmost layer of the cornea is not
at all hydrophilic, and in fact is believed to be somewhat
hydrophobic. This hydrophobic property can also be predicted from
the fact that the lacrimal film has a three-layer structure
comprising an oil layer (the uppermost layer), a water layer (the
middle layer), and a mucous layer (the lowermost layer) that is
contact with the corneal epithelium, and mutin, which is a mucous
component made up primarily of polysaccharide, is present in this
lowermost layer. Because its hydroxyl groups have been acetylated,
acetylated hyaluronic acid is more highly hydrophobic than
hyaluronic acid. Therefore, while not particularly bound to theory,
the reason that the moisture retention of acetylated hyaluronic
acid is better than that of hyaluronic acid, that is, that
acetylated hyaluronic acid remains on the cornea longer than
hyaluronic acid does, is believed to be that acetylated hyaluronic
acid is hydrophobic just like the corneal layer. Also, because it
is so highly hydrophilic, there is the danger that hyaluronic acid
will absorb moisture from the corneal epithelial tissue. In this
regard, acetylated hyaluronic acid is believed to absorb less
moisture from the corneal epithelial tissue because it is somewhat
less hydrophilic than hyaluronic acid.
[0010] The acetylated hyaluronic acid in the present invention is a
derivative in which the hydroxyl groups of hyaluronic acid have
been acetylated, and more specifically has the following structural
formula. ##STR1##
[0011] n is a natural number
[0012] Acetylated hyaluronic acid can be manufactured by any method
known to persons skilled in the art, and examples of such methods
are disclosed in Japanese Laid-Open Patent Application
H8-53501.
[0013] Preferably, the acetylated hyaluronic acid in the present
invention is obtained by suspending powdered hyaluronic acid in an
acetic anhydride solvent, and adding concentrated sulfuric acid to
bring about acetylation. With this method, an acetylated hyaluronic
acid with a high degree of acetylation can be obtained if acetic
acid is mixed with the acetic anhydride solvent and the ratio of
acetic acid to acetic anhydride is set between 1:4 and 1:1. Also,
acetylation will proceed more moderately and the degree of
acetylation can be fine tuned if acetic acid is mixed with the
acetic anhydride solvent and the ratio of acetic acid to acetic
anhydride is set between 2:1 and 4:1. The concentrated sulfuric
acid is preferably added to the solvent in an amount of 2 to 7 vol
%.
[0014] There are no particular restrictions on the acetyl group
substitution number of the acetylated hyaluronic acid pertaining to
the present invention, but 2.5 to 4.0 is preferable, 2.8 to 3.8 is
even better, and 3.0 to 3.8 is better yet. Ideally, the acetyl
group substitution number of the acetylated hyaluronic acid
pertaining to the present invention is approximately 3.3. It is
believed that the humectant effect attributable to hyaluronic acid
being inherently hydrophilic will be lost if the acetyl group
substitution number is too high, but that the humectant effect
attributable to acetylated hyaluronic acid being inherently
hydrophobic (which is assumed because the cornea is hydrophobic)
will be lost if the acetyl group substitution number is too low.
There are four alcoholic hydroxyl groups present in the repeating
units of hyaluronic acid, as indicated by Chemical Formula 1 above,
and "acetyl group substitution number" refers to how many of these
have been substituted with an acetyl group.
[0015] The above-mentioned acetylated hyaluronic acid can be
refined into high-purity acetylated hyaluronic acid by adding crude
acetylated hyaluronic acid to an acetone aqueous solution, adding
and dissolving sodium lactate, and adding a high concentration of
acetone. The above-mentioned sodium lactate is preferably added in
an amount of 1 to 3 wt % with respect to the acetone aqueous
solution.
[0016] "Hyaluronic acid" as used in the present invention means
hyaluronic acid and hyaluronates, and types of various molecular
weight can be used. There are no particular restrictions on the
average molecular weight of the acetylated hyaluronic acid
pertaining to the present invention, but it is preferably 1,000 to
1,000,000, and even more preferably 10,000 to 1,000,000. The ideal
average molecular weight is approximately 100,000.
[0017] The amount of acetylated hyaluronic acid contained in the
ophthalmic pharmaceutical composition of the present invention is
0.01 to 10 weight/volume (weight)%, and preferably 0.05 to 5
weight/volume (weight)%, and even more preferably 0.1 to 1
weigh/volume (weight)%, based on the total volume (or total weight)
of the pharmaceutical composition. The acetylated hyaluronic acid
concentration refers to the weigh/volume (w/v)% in the case of a
liquid eye wash or eyedrops, and to weigh/weight (w/w)% in the case
of a solid eye ointment. While it will depend on the hyaluronic
acid and its molecular weight, an aqueous solution in which the
concentration is over 3% usually cannot be used for eyedrops
because its viscosity will be too high, but preparing an aqueous
solution of acetylated hyaluronic acid with a concentration of
about 10% is quite possible.
[0018] The pH of the ophthalmic pharmaceutical composition of the
present invention is preferably close to neutral, and is usually
from 6.5 to 7.5. The osmotic pressure ratio is preferably adjusted
to about 0.5 to 4.0, with a range of 1.0 to 1.5 being even better.
Any means commonly employed for ophthalmic pharmaceutical
compositions can be used to adjust the pH and osmotic pressure.
[0019] The ophthalmic pharmaceutical composition pertaining to the
present invention is effective against symptoms of eye dryness, and
particularly in the treatment and prevention of dry eye. Dry eye
can be caused by a variety of factors, such as eyestrain, Sjogren's
syndrome, Stevens-Johnson syndrome, burns and injury to the eye,
and side effects of hypotensive drugs, tranquilizers, eyedrops for
treating glaucoma, and other such drugs. The ophthalmic
pharmaceutical composition of the present invention is formulated
as eyedrops, an eye wash, an eye ointment, or the like.
[0020] Depending on its formulation, the ophthalmic pharmaceutical
composition of the present invention can also be used together with
a pharmacologically acceptable carrier. The carrier for eyedrops
and eye washes can be any type ordinarily used for such purposes,
and purified water is favorable.
[0021] The ophthalmic pharmaceutical composition of the present
invention may optionally be compounded with various components
other than acetylated hyaluronic acid, such as sugars,
electrolytes, amino acids, vitamins, lipids, medicinal additives,
and medicines. Examples of these components include sugars such as
glucose, maltose, etc., oligosaccharides, mannitol, and sugar
alcohols such as sorbitol; electrolytes such as sodium chloride,
sodium hydrogenphosphate, potassium chloride, magnesium sulfate,
and calcium chloride; amino acids such as glycine and alanine;
vitamins such as thiamin hydrochloride, sodium riboflavin
phosphate, pyridoxine hydrochloride, nicotinic acid amide, folic
acid, biotin, vitamin A, L-ascorbic acid, and .alpha.-glycosyl
ascorbic acid; and derivatives of these. These may be compounded in
suitable combinations as needed.
[0022] As long as the humectant effect of the present invention is
not compromised, it is also possible to add any additives that are
used in ordinary ophthalmic preparations, examples of which include
preservatives such as methyl parahydroxybenzoate, sodium
dehydroacetate, and benzalkonium chloride; stabilizers such as
sodium edetate and sodium hydrogensulfite; buffers such as borax,
boric acid, and sodium hydrogencarbonate; thickeners such as methyl
cellulose, carboxymethyl cellulose, chondroitin sulfuric acid,
polyvinyl alcohol, and pullulan; and dissolution improvers such as
Polysorbate 80.
[0023] If the ophthalmic pharmaceutical composition of the present
invention is an ointment, any commonly used and pharmacologically
acceptable ointment carrier can be used, specific examples of which
include ophthalmic white vaseline and plastibase. Liquid paraffin
or the like may also be used as an additive. The ophthalmic
pharmaceutical composition of the present invention may
additionally contain as needed methylprednisolone and other such
steroidal hormones, tetracycline and other such antiphlogistics,
penicillin G and other such antibiotics, cyclosporin and other such
immunosuppressants, and pharmaceutical products such as
immunomodulators, analgesics, autoserum, and hyaluronic acid.
[0024] The dosage and method of administration of the ophthalmic
pharmaceutical composition of the present invention can be suitably
adjusted according to the symptoms of the patient. In the case of
an instillation, usually about one to four drops (assuming one drop
to be about 0.05 mL) are administered each time, either once or
several times daily (such as one to five times, and preferably one
to three times). In the case of an eye wash, the patient should use
a special eye wash container, a wash bottle, or the like, and wash
the eyes from one to several times a day (such as one to five
times, and preferably one to three times). In the case of an eye
ointment, the inside of the conjunctival sac should be coated with
a suitable quantity about one to three times a day.
[0025] The use of acetylated hyaluronic acid makes it possible to
provide an ophthalmic pharmaceutical composition for dry eye, which
remains on the cornea and exhibits a humectant effect over a longer
period than when hyaluronic acid is contained.
[0026] Examples of the present invention will now be given, but do
not limit the scope of the present invention.
EXAMPLES
[0027] In their research for the present invention, the inventors
examined the ability of acetylated hyaluronic acid (hereinafter
referred to as "AcHA") to suppress moisture evaporation, using a
soft contact lens (SCL) as a substitute for a human or animal
cornea, in an attempt to apply AcHA to an ophthalmic pharmaceutical
composition used for the treatment of dry eye.
Experimental Materials and Methodology
[0028] The SCLs used as a substitute cornea were Focus Dailies
(disposable, 13.8 mm diameter) from Ciba Vision (Tokyo).
[0029] The SCLs used in the experiment were made from Nelfilcon A,
which is a hydrogel based on a therapeutic material (polyvinyl
alcohol, PVA) that has good biocompatibility and is used for
surgical sutures and artificial blood vessels. This SCL retains a
large amount of water (69%) and has satisfactory oxygen
permeability. Accordingly, this SCL has good biocompatibility and
good affinity with the cornea, making it suitable as a substitute
cornea in physical property research such as this (such as
measuring the amount of moisture evaporation).
[0030] An isotonic phosphate buffer saline (PBS) (prepared from
Dulbecco's PBS (-) powder "Nissui" made by Nissui Pharmaceutical
(Tokyo)) was used as a control instillation, while Hyalein 0.1
(containing 0.1 w/v % sodium hyaluronate; average molecular weight
of hyaluronic acid: 600,000 to 1,200,000; made by Santen
Pharmaceutical (Osaka)) was used as a hyaluronic acid (HA)
instillation. The AcHA instillation was prepared by dissolving AcHA
(estimated average molecular weight of approximately 100,000;
acetylation substitution number of approximately 3.5) in PBS so
that the final concentration would be 0.1 w/v %.
[0031] The AcHA was prepared as follows.
[0032] Twenty milliliter of commercially available special grade
acetic acid and 80 mL of acetic anhydride were put in an Erlenmeyer
flask with a volume of 300 mL, to which 6 g of a fine powder of
hyaluronic acid (average molecular weight of approximately 1200 kd,
made by Shiseido) was added a little at a time while stirring. Four
milliliter of concentration sulfuric acid was then added slowly,
and the system was stirred for 1 hour at room temperature to bring
about an acetylation reaction. The reaction solution was in the
form of a viscous white liquid.
[0033] Two liter of purified water was put into a 3 L glass beaker,
and the above-mentioned reaction solution was slowly added in the
form of a fine stream while stirring. The precipitate of acetylated
hyaluronic acid thus produced was collected and washed twice with 2
L of purified water. This precipitate was then transferred to a 1 L
glass beaker, 250 mL of an aqueous 80% (v/v) acetone solution and 9
g of a 50% sodium lactate aqueous solution were added, and the
precipitate was completely dissolved under stirring. Four hundred
milliliter of acetone was then added slowly, and a gel of
acetylated hyaluronic acid was reprecipitated. This precipitate was
collected, after which it was washed twice for 10 minutes each time
in a homogenizer at a speed of 10,000 rpm and using 100 mL of
ethanol. The precipitate was then collected by reduced pressure
filtration, after which it was dried under reduced pressure, which
gave a white powder of acetylated hyaluronic acid.
Measurement Method
[0034] An AG64 balance made by Mettler Toledo was used to weigh the
SCL, and weight data were sent to and stored in a personal
computer. Nonparametric testing, which is not affected by the
distribution of data, was employed for the statistical analysis of
the data.
[0035] The experiments (the application of the eyedrops on SCLs,
leaving them in the eyes, and measuring the weight of SCLs) were
conducted in a thermohygrostatic room at a temperature of
25.degree. C. and a humidity of 50%. Each SCL packaged in a
isotonic phosphate buffer was taken out with dental forceps and
placed convex-side up on the pre-weighed lid (30 mm diameter) of a
plastic petri dish, the weight of the petri dish including the SCL
was measured, and 20 .mu.L of sample instillation was immediately
dropped onto the center of the SCL. After 20 minutes had elapsed,
the weight of the petri dish including the SCL was measured, and
another 20 .mu.L of sample instillation was immediately dropped
onto the center of the SCL. This cycle of measurement and sample
dropping was repeated a total of four times at 20 minute intervals.
After the final sample dropping, the SCL was weighed every 20
minutes until 120 minutes after the start of the experiment.
Experiment Results
[0036] As shown in Table 1 below, the SCLs in the AcHA instillation
group at 120 minutes after the start of the experiment had
significantly lower moisture evaporation amounts than the control
instillation group or the HA instillation group. TABLE-US-00001
TABLE 1 Relative wet weight (%) of soft contact lens after several
instillations Time Control HA AcHA (min) instillation instillation
instillation 80 130.4 145.2*.sup.a 149.2*.sup.b 100 105.1
118.1*.sup.a 123.9*.sup.b 120 82.13 86.03 99.8*.sup.b,*.sup.c
*.sup.awith respect to the control instillation group; p < 0.05)
*.sup.bwith respect to the control instillation group; p < 0.05)
*.sup.cwith respect to the HA instillation group; p < 0.05)
[0037] The numerical values are the median value for each group,
and the number of observations was 5 for the control instillation
group and HA instillation group, and 4 for the AcHA instillation
group. The Mann-Whitney method (a nonparametric test) was used for
a significant different test.
CONCLUSION
[0038] The evaporation of moisture from an SCL was significantly
suppressed with a 0.1% AcHA instillation. It is clear from this
that the AcHA instillation has the potential for application as an
instillation in the treatment of dry eye. TABLE-US-00002 AcHA
instillation composition acetylated hyaluronic acid 0.1 g
benzalkonium chloride 0.002 g isotonic phosphate buffer q.s. total
100 mL
[0039] With the above composition, AcHA can be contained in an
amount of about 0.1 to 10 g, and since AcHA has a high molecular
weight (approximately 100,000), even at a high concentration it
will be unlikely to have an effect on the osmotic pressure ratio of
the instillation.
* * * * *