Field of the Invention
This invention relates to pharmaceutical ophthalmic compositions compnsmg active
ingredient(s) such as carbonic anhydrase inhibitor (CAI) or combinations and processes for
making such compositions and the use of these compositions in patient populations including
pediatric populations.
Background of the Invention
Many useful ophthalmic compounds are solids. Those solids which are soluble in ophthalmic
carriers or vehicles present little or no difficulty when preparing a composition for
ophthalmic use. However, those solids which are insoluble in ophthalmic carriers must be
formulated as compositions such as suspensions or emulsion in order to obtain a proper
delivery system. Moreover, forms of useful ophthalmic compounds which are insoluble in
ophthalmic carriers are often found desirable in order to prolong the particular therapeutic
action of the compound.
A pharmaceutically acceptable ophthalmic composition possesses certain essentinl
characteristics, among which are: (1) the dispersed or suspended material should not settle
too rapidly from the carrier to be available in the required concentration in the carrier for
effective administration to the eye of the patient; (2) the particles of dispersed or suspended
material which do finally settle to the bottom of the vessel holding the composition must not
form an intractable hard cake but should be readily re-dispersed into a uniform composition
when the vessel is shaken; (3) the particles size of the dispersed materials should be fine
enough to avoid any irritation to the eye.
Major problems related to ophthalmic compositions are crystallization and agglonleration of
active ingredients during preparation as well as during storage. Crystallization or
agglomeration of active leads to non-uniformity of dose, difficulty of administration.
irritation to eye due to large drug particles and! or any ocular adverse effect due to high drug
concentration or failure of treatment due to low drug concentration.

In most cases crystallization of active ingredients useful for ophthalmic use like carbonic
anhydrase inhibitor, beta- blockers or others actives, occurs during preparation. Sterilization
by autoclaving leads to increase in solubility of the actives in the preparation and large
crystals are formed during cool down phase. Aseptic ball milling of this final composition is
not always practical. Aseptic addition of the all actives to a sterile vehicle is also not practical
as the all actives cannot be sterilized by conventional means due to stability problem. Dry
heat sterilization causes melting of the material. Sterilization by ethylene oxide introduces
unacceptable degradation products and residues, and sterilization by gamma irradiation of
micronized material produces degradation products unacceptable for regulatory filing.
Another reason for crystallization is change in pH due to addition of salts, acids or bases.
During storage, the composition is left standing for a long time, hence secondary particles are
formed due to partial agglomeration caused by mutual adhesion of suspended particles, or a
hard deposit layer (caking) on the bottom surface of a container; or may have a lowered pH.
Such formation of secondary particles or caking causes problems in terms of particle size and
re-dispersibility (hereinafter secondary particles and caking are sometimes integrally referred
to as agglomerates). It has been found that the caking is common problem due to unequal
particle size distribution. The fine particles take the void space in-between the large particles
and form strong caking.
In one preferred embodiment, the pharmaceutical ophthalmic compositions compnse
pharmaceutically active carbonic anhydrase inhibitors (CAls) such as R 4-ethylamino-3,4-
dihydro-2-(3-methoxy)propyl-2H -thieno [3,2-e ]-1 ,2-thiazine-6-sulfonamide 1,1 dioxide,
which is known as brinzolamide. This compound is disclosed in U.S. Pat. No. 5,37S,703
(Dean, et al.).
US Pat. No. 6,071,904 discloses processes for preparation of brinzolamide ophthalmic
composition.

We have now developed simpler and cost effective processes) to prepare phannaceutical
ophthalmic compositions.
Brief Description of the Drawing
FIG. I is a flow diagram showing the process for making pharmaceutical ophtbalmic
composition of active ingredient(s) such as carbonic anhydrase inhibitor (e.g. brinzolamide)
by two stage autoclaving and sizing of drug concentrate using microfludizer under aseptic
condition.
FIG. II is a flow diagram showing the process for pharmaceutical ophthalmic composition of
active ingredient(s) such as carbonic anhydrase inhibitor (e.g. brinzolamide) by single stage
autoc1aving and sizing using microfludizer under aseptic condition.
FIG. III is a flow diagram showing the process for making pharmaceutical ophthalmic
composition of active ingredient(s) such as carbonic anhydrase inhibitor (e.g. brinzolamide)
by single stage autoc1aving and sizing using ball mill under aseptic condition.
FIG. IV is a flow diagram showing the process for making pharmaceutical ophthalmic
composition of active ingredient(s) such as carbonic anhydrase inhibitor (e.g.brinzolamide )
by single stage autodaving and sizing using colloidal mill/ homogenizer under aseptic
condition.
Summary of the Invention
One of the embodiments relates to pharmaceutical ophthalmic composition comprising active
ingredient(s) such as carbonic anhydrase inhibitor (CAI) or combinations and pracesses for
making such compositions and the use of these compositions in patient populatious including
pediatric populations.

Another embodiment relates to a process for preparing a ophthalmic composition comprising
the steps of autoclaving a homogenously dispersed slurry comprising active ingredient(s)
such as carbonic anhydrase inhibitor and surfactant(s); sizing the particles of active
ingredient(s) of the homogenously dispersed slurry of a by microfludizer; preparing a
polymer slurry comprising polymer and water; preparing a solution comprising tonicity and
preservative agents; mixing the polymer slurry and the solution to form a vehicle concentrate
and adjusting pH; autoclaving the vehicle concentrate; and aseptically adding the sized active
ingredient(s) slurry through a screen to the sterilized vehicle concentrate.
Another embodiment relates to a process for preparing a ophthalmic composition comprising
the steps of preparing a homogenously dispersed slurry comprising active ingredient(s) such
as carbonic anhydrase inhibitor and surfactant(s); preparing a polymer slurry comprising
polymer and water; preparing a solution comprising tonicity and preservative agents; mixing
the polymer slurry and the solution to form a vehicle concentrate and adjustilig pH;
aseptically adding the homogenously dispersed active ingredient(s) slurry through a screen to
the sterilized vehicle concentrate and mixing to homogenize; autoclaving the active
ingredient(s) slurry and vehicle concentrate mixture; and finally, sizing the particles of active
ingredient(s) such as carbonic anhydrase inhibitor of the autoclaved mixture by microfludizer
under aseptical condition.
Detailed Description of the Invention
This invention relates to pharmaceutical ophthalmic compositions comprising active
ingredient(s) such as carbonic anhydrase inhibitor (CAI) or combinations thereof and
processes for making such compositions.
The term "composition" means a liquid or semi-liquid having solid particles homogeneously
dissolved or dispersed in pharmaceutically acceptable solvent or carrier system with or
without additional ophthalmic excipient(s). It includes suspension, emulsions, drops,
solutions and the like.

The active ingredient is defined as the chemical substance, which is used in the prevention or treatment of various diseases associated with human or non-human animals. The preferred active ingredient includes but are not limited to the active which is useful in the treatment or prevention of diseases associated to eye like elevated intraocular pressure in patients with ocular hypertension or open-angle glaucoma, ocular surface pain. uveitis, scleritis, episcleritis, keratitis, surgically-induced inflammation, endophthalmitis. iritis, atrophic macular degeneration, retinitis pigmentosa, iatrogenic retinopathy, retinal tears and holes, cystoid macular edema, diabetic macular edema, diabetic retinopathy, siekle cell retinopathy, retinal vein and artery occlusion, optic neuropathy, exudative macular degeneration, neovascular glaucoma, corneal neovascularization, cyclitis, sickle cell retinopathy, pterygium, seasonal allergic conjunctivitis, palpebral and bulbar conjunctiva, acne rosacea, superficial punctuate keratitis, herpes zoster keratitis, iritis, cyclitis, selected infective conjunctivitides, post-operative inflammation following ocular surgery.
The active ingredient used in the pharmaceutical ophthalmic composition, may be a soluble or sparingly soluble or slightly soluble or very slightly soluble or practically insoluble compound(s) selected from the group but are not limited to a carbonic anhydrase inhibitor (CAI), such as brinzolamide, acetazolamide, dorzolamide, methazolamide; a beta-blocker, such as timolol, arteolol, metopranolol, betaxolo; non steroidal anti-inflammatory drugs (NSAID), such as nepafenac, flurbiprofen, diclofenac and ketorolac tromethamine; an antifungal agent, such as natamycin, amphotericin-B; an α-2 adrenergic agonist, such as epinephrine, dipivefrin, brimonidine, apraclonidine; a prostaglandin analog, such as latanoprost, travoprost, bimatoprost; a phosphodiesterase IV inhibitor (PDE-IV or PDE-4) inhibitor, such as roflumilast; a receptor tyrosine kinase inhibitor; a steroid, such as fluorometholone, hydrocortisone, dexamethasone, prednisolone, loteprednol, or medrysone; an antibiotic; an antibacterial agent[0]s or other actives used for ophthalmic formulation or a pharmaceutically acceptable salt(s), hydrate(s), solvate(s), polymorph(s), stereoisomer(s), ester(s), prodrug(s), complex(es) and their metabolites thereof. All of the foregoing actives are known compounds and can be made by known methods and can be used in various

combinations. One of the preferred active is a CAI, or a beta-blocker or a steroid. In a
preferred embodiment the CAI is brinzolamide, can be in combination with a beta-blocker.
The term active ingredient(s) can be interchangeably used with their pharmaceutically
acceptable salt(s), hydrate(s), solvate(s), polymorph(s), stereoisomer(s), ester(s), prodrug(s),
complex( es) and their metabolites thereof.
The pharmaceutical ophthalmic composition compnses a pharmaceutically acceptable
solvent or carrier system and an active ingredient dispersed in said solvent or carrier system.
The pharmaceutically acceptable solvent may be, for example, an aqueous solvent such as
water, physiological saline and buffer. While the active ingredient content may vary
depending on type of active, diseases to be treated and the like, it is generally present in a
proportion of 0.005-20.0 w/v %, preferably 0.005-5.0 w/v % relative to the entire
composition. The pharmaceutically acceptable solvent or carrier system is defined as the
media in which the active is dispersed and may be aqueous or buffer system or likewise. The
solvent or carrier system may contain various additives such as a viscosity agent, a stabilizer,
a preservative, a surfactant, an antioxidant, a chelating agent, a pH adjusting agent a
thickener and an absorption promoter which are known to a skilled person in art.
The viscosity agents used in the pharmaceutical ophthalmic composition may ,comprise a
water soluble polymer for enhancing dispersion stability. Examples of the water soluble
polymer include but not limited to polymers like polyacrylic acids (e.g. carbomer),
hydroxypropyl-methylcellulose, polyvinyl alcohol, hydroxyethylcellulose,
hydroxypropylcellulose, polyvinylpyrrolidone, polyethylene glycol, sodium
carboxymethyl cellulose, methylcellulose, ethylcellulose, sodium alginate, gelatin,
carboxyvinyl polymer and mixtures thereof. Other suspending agents known in the field of
pharmaceutical preparation may be also contained. Of the above-mentioned water soluble
polymers, polymer like carbomer, hydroxypropylmethylcellulose and polyvinyl alcohol are
preferable, since they suppress formation of agglomerates, prevent lowering of pH, and

provide a composition superior in redispersibility and stability. The water soluble polymer is
generally present in a composition in a proportion of 0.0 1-2.0 w/v %, preferably 0.02-1.0 w/v
%, more preferably 0.03-0.8 w/v % relative to the entire composition.
The surfactants used in the pharmaceutical ophthalmic composition for enhancing dispersion
stability preferably include nonionic surfactant(s). The nonionic surfactant to be used is nontoxic,
non-irritant and applicable to the eye. Non-limiting examples of the nonionic surfactant
include polymer of the alkyl aryl polyether alcohol like tyloxapol; polyoxyethylene
polyoxypropylene polymer like triton X-100; polyoxyethylenesorbitan fatty acid esters such
as polyoxyethylenesorbitan monooleate, polyoxyethylenesorbitan monolaurate.
polyoxyethylenesorbitan monopalmitate and polyoxyethylenesorbitan monostearate;
polyoxyethylene hydrogenated castor oils; sorbitan fatty acid esters such as sorbitan
monooleate, sorbitan monolaurate, sorbitan monopalmitate and sorbitan monostearate;
polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether; and polyoxyethylene fatty
acid esters such as polyoxyethylene monostearate and mixtures thereof. Of the recited
nonionic surfactants, alkyl aryl polyether alcohol like tyloxapol, polyoxyethylene
polyoxypropylene polymer like triton X-100 are preferable, since they suppress formation of
agglomerates, prevent lowering of pH, and provide a composition superior in redispersibility
and stability. The nonionic surfactant is generally contained in a proportion of 0.005-1.0 w/v
%, preferably 0.01-0.5 w/v % and more preferably 0.05-0.3 w/v % relative to the entire
composition.
The pharmaceutical ophthalmic composition optionally compnses preservative(s) for
preventing contamination with microorganisms such as fungi and bacteria. The preservative
usable has antibacterial action and antifungal action, and should be non-toxic, non-irritant
and applicable to the eye. Examples of the preservative include quaternary ammonium salts
such as benzalkonium chloride and benzethonium chloride; cationic compounds such as
chlorhexidine gluconate; p-hydroxybenzoates such as methyl p-hydroxybenzoate, ethyl
p-hydroxybenzoate, propyl p-hydroxybenzoate and butyl p-hydroxybenzoatc; alcchol
compounds such as chlorobutanol and benzyl alcohol; sodium dehydroacetate; and

thiomersal and mixtures thereof. Of the recited preservatives, quaternary ammonium salts
and cationic compounds are preferable as they suppress formation of agglomerates, prevent
lowering of pH, and provide a composition superior in redispersibility and stability. Of the
quaternary ammonium salts, benzalkonium chloride and benzethonium chloride are
particularly preferable, and chlorhexidine gluconate is particularly preferable as the cationic
compound. The preservative is generally contained in a proportion of 0.001-0.3 w/v %,
preferably 0.002-0.05 w/v % and more preferably 0.005-0.01 w/v % relative to the entire
composition.
Non-limiting examples of tonicity agents include sodium chloride, glycerol, glucose,
mannitol and sorbitol, which are conventionally used for eye drops. Of these, sodium
chloride is preferable as it possesses superior dispersibility when formulated into a
preparation, suppresses formation of agglomerates and provides a composition superior in
redispersibility. The tonizing agent is added in such an amount that makes the osmotic
pressure of the composition identical to that of tears.
The pharmaceutical ophthalmic composition may further include a buffer. The buffer should
have buffering capacity in the range of pH 5.0-8.5. Examples of the buffer include acetates
such as sodium acetate; phosphates such as sodium dihydrogenphosphate, disodium
hydrogenphosphate, potassium dihydrogenphosphate and dipotassium hydrogenphosphate; caminocaproic
acid; amino acid salts such as sodium glutamate; and boric acid and a salt
thereof. Of the mentioned buffers, acetates and c-aminocaproic acid are preferable as they
suppress formation of agglomerates, prevent lowering of pH, and provide a composition
superior in redispersibility and stability. As the acetate, sodium acetate is particularly
preferable. The buffer is generally contained in a proportion of 0.01-2.0 w/v %, preferably
0.05-0.5 w/v % relative to the entire composition.
Examples of the pH adjusting agent include hydrochloric acid, citric acid, phosphoric acid,
acetic acid, tartaric acid, sodium hydroxide, potassium hydroxide, sodium carbonate and

sodium hydrogencarbonate. The pharmaceutical ophthalmic composition IS generally
adjusted to pH 4-10, the range which is less irritating to the mucosal membrane of the eye.
Suitable chelating agents include edetate disodium, edetate trisodium, edetate tetrasodium,
diethyleneamine pentaacetate and mixtures thereof. Most preferred is edetate disodium. The
chelating agent is generally present in an amount from 0.00 1 - 0.1 w/v % relative to the entire
composition. In the case of edetate disodium, the chelating agent is preferably present at a
concentration of 0.005 - 0.05 w/v % relative to the entire composition.
Examples of the antioxidant include ascorbic acid, sodium ascorbate, tocopherol and sulfite
salts like sodium sulfite, potassium sulfite, magnesium sulfite, calcium sulfite, sodium
bisulfite, potassium bisulfite, magnesium bisulfite, calcium bisulfite, sodium metabisulfite,
potassium metabisulfite, calcium metabisulfite, sodium thiosulfate and sodium
hydrogensulfite. The sulfite salt is generally be present in an amount from 0.01 - 1 % w/v %
relative to the entire composition.
The average particle size of the dispersed or the suspended active is generally 0.0 1-100 μm.
The more acceptable particle size range is 0.01-50 μm, preferably 0.01-30 μm, more
preferably 0.1-20j.lm and most preferably 0.1-5.0 μm. The use of the active in this particle
size range affords a composition having superior dispersibility, which is less irritating to the
mucosal membrane of the eye.
In one embodiment, microfluidization technique is used for sIzmg of particles in the
preparation of pharmaceutical ophthalmic composition. There are various advantages of
Microfluidizer Processor Technology which include much smaller particle and droplet size;
much more uniform particle and droplet size distribution; faster processing times (>2 orders
of magnitude in some applications); better control of the amount of energy applied; much
higher energy (up to 40,000 psi sustained); scalability from small batches• to• contin\1011s
production; no moving parts in the interaction chamber; easy to clean in many applications;
little or no contamination; uniform and dispersions and emulsions; highly repeatable process

from run to run or batch to batch. Additional advantages are lower processing cost, increased
speed of operation and more flexible manufacturing capability in the face of evolving market
opportuni ties.
One of the embodiments relates to various processes to prepare pharmaceutical ophthalmic
composition.
In one embodiment the process to prepare a pharmaceutical ophthalmic composition
comprises one or two stage sterilization by autoclaving and use of microfluidization
technique for sizing of particles.
In another embodiment the process to prepare a pharmaceutical ophthalmic composition
comprises one stage sterilization by autoclaving and use of ball mill for sizing of particles.
In another embodiment the process to prepare a pharmaceutical ophthalmic composition
comprises one stage sterilization by autoclaving and use of colloidal mill or homogenizer for
sizing of particles.
In another embodiment the process to prepare a pharmaceutical ophthalmic composition
comprises use of micro fluidization technique for sizing of particles of active ingredient(s)
such as carbonic anhydrase inhibitor (e.g. brinzolamide).
In another embodiment the process to prepare a pharmaceutical ophthalmic composition
comprises one or two stage sterilization by autoclaving and use of micro fluidization
technique for sizing of particles of active ingredient(s) such as carbonic anhydrase inhibitor
(e.g. brinzolamide).

In another embodiment the process to prepare a pharmaceutical ophthalmic composition
comprises one stage sterilization by autoclaving and use of ball mill for sizing of particles of
active ingredient(s) such as carbonic anhydrase inhibitor (e.g. brinzolamide).
In another embodiment the process to prepare a pharmaceutical ophthalmic composition
comprises one stage sterilization by autoclaving and use of colloidal mill or homogenizer for
sizing of particles of active ingredient(s) such as carbonic anhydrase inhibitor (e.g.
brinzolamide ).
Another embodiment processes for preparmg pharmaceutical ophthalmic compositions
comprising brinzolamide.
The process for making pharmaceutical ophthalmic composition of active ingredient(s) such
as carbonic anhydrase inhibitor, more preferably brinzolamide, uses autodaving of
concentrated slurry of brinzolamide and then sizing brinzolamide particles by using
microfluidizer and then adding the slurry to the rest of the autoclaved ingredients as shown in
FIG. I.
Referring to FIG. I, first the menstruum comprising surfactant(s) such as Tyloxapol or Triton
X-I00 is prepared by dissolving in purified water and filtering through 2-5 /lm filter. The
active ingredient(s) such as carbonic anhydrase inhibitor, more preferably brinzolamide
(particle size: d(09)< 20 /lm and preferably < 10 /lm) is added to the above menstruum under
stirring in vortex mixer to obtain a homogenous dispersion. The above homogenous
dispersion is sterilized by autoclaving at normal temperatures and pressures known to those
skilled in the art, e.g., 110-129° C, preferably 121-127° C, for 30 min to 3 hour. The particles
of sterilized dispersion are sized by passing through a micro fluidizer to obtain dispersion
with average particle size distribution in the range 0.2-10 /lm under aseptic condition.

After sizing, the micronized slurry is aseptically added through a screen to the rest of the
ingredients including, water, one or more tonicity agents, one or more preservatives, and at
least one polymer which are mixed, filtered, pH adjusted, and sterilized prior to their
combination with the milled mixture. The purified water is used to rinse the microfluidizer is
then added to the mixture and the batch is brought to final volume aseptically and mixed until
homogeneous.
Referring to FIG. II, the process for preparing composition is different from FIG. 1. In this
process, the active ingredient(s) such as carbonic anhydrase inhibitor, more preferably
brinzolamide homogenous dispersion is aseptically added to the rest of the ingredients
including, water, one or more tonicity agents, optionally one or more preservatives, and at
least one polymer which are mixed, filtered, pH adjusted and then homogenized. The
homogenized slurry is made up to the final volume, sterilized by autoclaving and then
particle sizing is done by micro fluidizer.
Referring to FIG III & IV, the process for preparing composition is same as shown in FIG II
but using different types of sizing techniques like ball milling and colloidal milling
respectively.
Given below are the examples which merely as illustration of pharmaceutical ophthalmic
composition and do not restrict the general concept of the invention.

Brief manufacturing procedure
The processes for preparation of pharmaceutical ophthalmic compositions are as set forth.
Method 1: Two Stage Autoclaving and Sizing of Drug Concentrate Using Microfluidizer
Step-A: API slurry preparation:
1. Dissolve Tyloxapol or Triton x-loa in purified water & filter through 2-5 μm filter.
2. Add Brinzolamide (particle size: d(o.9)< 20 μm and preferably < 10 μm) to solution of
step I under stirring using a vortex mixer to obtain a homogenous dispersion.
3. Sterilize the dispersion of step 2 by autoclaving.
4. Pass the sterilized dispersion of step 3 through microfluidizer to obtain dispersion
with average particle size distribution in the range 0.2-10 μm under aseptic condition.
Step-B: Preparation of vehicle concentrate:
5. Add carbomer in sufficient quantity of purified water under continuous stirring in
vortex mixer to obtain a uniform dispersion and filter through suitable filter (NMT 10
μm).

6. Dissolve required quantity of mannitol, sodium chloride, benzalkonium chloride &
edetate disodium in sufficient quantity of purified water and filter through suitable
filter (2-5 μm).
7. Mix solution of step 6 to the dispersion of step 5 under stirring in vortex mixer to
obtain vehicle concentrate.
8. Adjust the pH of the dispersion.
9. Sterilize the dispersion of step 8 by autoclaving.
Step-C: Preparation of final composition (In aseptic area):
10. Aseptically pump output of Step A & B into mixer/ homogenizer under continuous
stirring.
11. Make up the volume to 100% batch size using sterile water rinse.
12. Homogenize the mixture, if required.
13. Bulk volume obtained is aseptically filled and sealed in unit containers.
Method 2: Single Stage Autoclaving and Sizing of the Final Dispersion by
Microfluidizer
Step-A: API slurry preparation:
1. Dissolve Tyloxapol or Triton X-100 in purified water & filter through 2-5 11mfilter.
2. Add Brinzolamide (particle size: dco.9) < 20 μm and preferably < 10 μm)to solution of
step 1 under stirring using a vortex mixer to obtain a homogenous dispersion.
Step-B: Preparation of vehicle concentrate:
3. Add carbomer in sufficient quantity of purified water under continuous stirring in
vortex mixer to obtain a uniform dispersion and filter through suitable filter (NMT 10
μm).
4. Dissolve required quantity of mannitol, sodium chloride, benzalkonium chloride &
edetate disodium in sufficient quantity of purified water and filter through suitable
filter (2-5 μm).

5. Mix solution of step 4 to the dispersion of step 3 under stirring in vortex mixer to
obtain vehicle concentrate.
6. Adjust the pH of the dispersion.
Step-C: Preparation of final composition (In aseptic area):
7. Mix output of Step A & B in mixer/ homogenizer until a uniform dispersion is
obtained.
8. Make up the volume to 100% batch size using sterile water rinse.
9. Re-homogenize the dispersion, if required.
10. Sterilize the dispersion of step 9 by autoclaving.
11. Pass the sterilized dispersion of step 10 through microfluidizer to obtain dispersion
with average particle size distribution in the range 0.2-10 μm under aseptic condition.
12. Bulk volume obtained is aseptically filled and sealed in unit containers.
Method 3: Single Stage Autoclaving and Sizing of the Final Dispersion by Ball Milling
Step-A: API slurry preparation:
1. Dissolve Tyloxapol or Triton X-100 in purified water & filter through 2-5 μm filter.
2. Add Brinzolamide (particle size: d(0.9) < 20 μm and preferably < 10μm) to solution of
step 1 under stirring using a vortex mixer to obtain a homogenous dispersion.
Step-B: Preparation of vehicle concentrate:
3. Add carbomer in sufficient quantity of purified water under continuous stirring in
vortex mixer to obtain a uniform dispersion and filter through suitable filter (NMT 10
μm).
4. Dissolve required quantity of mannitol, sodium chloride, benzalkonium chloride &
edetate disodium in sufficient quantity of purified water and filter through suitable
filter (2-5 μm).
5. Mix solution of step 4 to the dispersion of step 3 under stirring in vortex mixer to
obtain vehicle concentrate.

6. Adjust the pH of the dispersion.
Step-C: Preparation of final composition (In aseptic area):
7. Mix output of Step A & B in mixer/ homogenizer until a uniform dispersion is
obtained.
8. Sterilize the dispersion of step 7 along with milling beads by autoclaving in ball mill
bottle.
9. Aseptically mill the dispersion of step 10 in ball mill to obtain dispersion with
average particle size distribution in the range 0.2-1 0 μm under aseptic condition.
10. Pass the sized dispersion through suitable screen.
11. Make up the volume to 100% batch size using sterile water rinse.
12. Re-homogenize the dispersion, if required.
13. Bulk volume obtained is aseptically filled and sealed in unit containers.
Method 4: Single Stage Autoclaving and Sizing of the Final Dispersion by Colloidal
MillI Homogenizer
Step-A: API slurry preparation:
1. Dissolve Tyloxapol or Triton X-100 in purified water & filter through 2-5 μm filter.
2. Add Brinzolamide (particle size: d(0.9)< 10 μm and preferably < 5 μm) to solution of
step 1 under stirring using a vortex mixer to obtain a homogenous dispersion.
Step-B: Preparation of vehicle concentrate:
3. Add carbomer in sufficient quantity of purified water under continuous stirring in
vortex mixer to obtain a uniform dispersion and filter through suitable filter (NMT 10
μm).
4. Dissolve required quantity of mannitol, sodium chloride, benzalkonium chloride &
edetate disodium in sufficient quantity of purified water and filter through suitable
filter (2-5 μm).

5. Mix solution of step 4 to the dispersion of step 3 under stirring in vortex mixer to
obtain vehicle concentrate.
6. Adjust the pH of the dispersion.
Step-C: Preparation of final composition (In aseptic area):
7. Mix output of Step A & B in mixer/ homogenizer until a uniform dispersion is
obtained.
8. Sterilize the dispersion of step 7 by autoclaving.
9. Autoclave the required colloidal mill components.
10. Aseptically mill the dispersion of step 10 in colloidal mill to obtain dispersion with
average particle size distribution in the range 0.2- 5 μm under aseptic condition.
11. Make up the volume to 100% batch size using sterile water rinse.
12. Re-homogenize the dispersion, if required.
13. Bulk volume obtained is aseptically filled and sealed in unit containers.

We Claim:
1. A process for preparing an ophthalmic composition comprising a carbonic
anhydrase inhibitor, which comprises
a) preparing a slurry comprising a carbonic anhydrase inhibitor and a surfactant;
b) preparing a polymer slurry comprising a polymer and water;
c) preparing a solution comprising tonicity and preservative agents;
d) mixing the polymer slurry of step b and the solution of step c, to form a vehicle concentrate and adjusting pH;
e) adding the slurry of step a, to the vehicle concentrate of step d and mixing to homogenize;
f) autoclaving the mixture of step e;
g) sizing the mixture of step f, under aseptic condition.

2. The process of claim 1 wherein the carbonic anhydrase inhibitor is brinzolamide.
3. The process of claim 1 wherein sizing is carried out by using microfluidizer, ball mill or colloidal mill.
4. The process of claim 1 wherein the polymer is selected from carbomer, hydroxypropylmethylcellulose, polyvinyl alcohol, hydroxyethylcellulose, hydroxypropylcellulose, polyvinylpyrrolidone, polyethylene glycol, sodium carboxymethylcellulose, methylcellulose, ethylcellulose, sodium alginate, gelatin, carboxyvinyl polymer or mixtures thereof.
5. The process of claim 1 wherein the surfactant is selected from alkyl aryl polyether alcohol, polyoxyethylene polyoxypropylene polymer, polyoxyethylenesorbitan fatty acid esters, polyoxyethylene hydrogenated castor oils, sorbitan fatty acid esters, polyoxyethylene alkyl ethers, polyoxyethylene fatty acid esters or mixtures thereof.
6. The process of claim 1 wherein the preservative is selected from benzalkonium chloride, benzethonium chloride, chlorhexidine gluconate, methyl p-hydroxybenzoate, ethyl p-hydroxybenzoate, propyl p-hydroxybenzoate, butyl p-

hydroxybenzoate, chlorobutanol, benzyl alcohol, sodium dehydroacetate, thiomersal or mixtures thereof.
7. The process of claim 1 wherein the tonicity agent is selected from sodium chloride, glycerol, glucose, mannitol, sorbitol or mixtures thereof.
8. A process for preparing an ophthalmic composition comprising a carbonic anhydrase inhibitor, which comprises

a) autoclaving a slurry comprising a carbonic anhydrase inhibitor and a surfactant;
b) aseptically sizing the particles of the dispersed slurry of step a by microfludizer;
c) preparing a polymer slurry comprising a polymer and water;
d) preparing a solution comprising tonicity and preservative agents;
e) mixing the polymer slurry of step c and the solution of step d to form a vehicle concentrate and adjusting pH;
f) autoclaving the vehicle concentrate; and
g) aseptically adding the slurry of step b to the sterilized vehicle concentrate of step f.
9. The process of claim 8 wherein the carbonic anhydrase inhibitor is brinzolamide.