in another embodiment , brinzolamide is sterilized by dry heat , gamma radiation , ethylene oxide sterilization or autoclaving . in another embodiment , wherein the sterilization is done by using a method selected from a group comprising filtration , autoclaving , heating , irradiation , and combination thereof . the present invention comprises a solvent wherein brinzolamide is dispersed in said solvent comprising aqueous solvent such as water . in another embodiment the solvent system may contain one or more excipients selected from chelating agent , surfactant , preservative and ph adjusting agent . in another embodiment , brinzolamide may be present in an amount of from about 0 . 001 w / v % to 10 . 0 w / v % and the particle size may range from 1 to 10 microns more preferably less than 5 microns . suitable polymers used according to the present invention are selected from a group comprising carboxyvinyl polymer ( carbopol - 974p ), povidone , hydroxypropylmethylcellulose , hydroxypropylcellulose , methyl cellulose , ethyl cellulose , hydroxyethylcellulose and mixtures thereof . the amount of polymer may range from about 0 . 01 to 2 . 0 w / v %. the surfactant used according to present invention is non - toxic , non - irritant and applicable to the eye . suitable surfactants are selected from a group comprising tyloxapol ®, triton x - 100 ®, polysorbates , polyoxyl 35 castor oil , polyoxyl 40 hydrogenated castor oil , polyoxyl 40 stearates , sorbitan esters , polyoxyethylene sorbitan esters , sorbitan monolaurates , sodium lauryl sulphate , polyethylene - propylene glycol copolymer ( poloxamer ), cremophor - 40 , propylene glycol , polyvinyl alcohol and mixtures thereof . the amount of surfactant may range from about 0 % to 1 . 0 w / v %. suspensions that are isotonic with the lachrymal secretions cause minimal discomfort to the corneal tissue . hence , the tonicity of the suspension has to be adjusted to maintain the formulation at an osmolality of at least about 300 mosmol / kg . suitable tonicity agents are selected from the group comprising mannitol , sorbitol , dextrose , dextran , glucose , glycerin , potassium chloride , sodium chloride and mixtures thereof . ophthalmic formulations are typically packed in multidose form . in order to inhibit the growth of microbial contaminants and suppress biodegradation preservatives are added . suitable preservative is selected from a group comprising benzalkonium chloride , benzethonium chloride , chlorhexidine gluconate , chlorobutanol , benzyl alcohol , sodium dehydroacetate , p - hydroxybenzoate and mixtures thereof and the like . the amount of preservatives may range from about 0 % to 1 . 0 w / v %. suitable ph modifiers are selected from a group comprising hydrochloric acid , acetic acid , phosphoric acid , sodium hydroxide , potassium hydroxide , ammonium hydroxide and mixtures thereof . suitable chelating agent is selected from a group comprising edetic acid , edetic acid salts like disodium edetate , sodium edetate , edetate calcium and trisodium edetate and the like . in another embodiment , the present invention also provides sterile ophthalmic suspension prepared by the process as described herein comprising brinzolamide , polymer , surfactant and one or more excipients and optionally a beta blocker such as atenolol , timolol , betaxolol , arteolol and / or alpha adrenergic agonist such as brimonidine , epinephrine . according to a preferred embodiment , the present invention provides brinzolamide ophthalmic suspensions comprising brinzolamide , tyloxapol ®; carbopol ® 974 p ; mannitol , sodium chloride , edetate disodium , benzalkonium chloride ; sodium hydroxide and / or hydrochloric acid ( to adjust the ph ) wherein the said ophthalmic suspension is prepared by the process as described herein . in another embodiment homogenization is done using ball mill , colloidal mill or microfluidizer for sizing of particles in the suspension . in another embodiment , the present invention provides a process for preparing sterile ophthalmic suspension of brinzolamide comprising the steps of : ( c ) combining the slurry of step ( a ) and step ( b ) and milling the said slurry , ( g ) aseptically combining the slurry of step ( d ) and the solution of step ( 0 to form a suspension and adjusting the ph , in yet another embodiment , the present invention provides a process for preparing sterile ophthalmic suspension of brinzolamide comprising the steps of : ( c ) combining the slurry of step ( a ) and step ( b ) and milling the said slurry , ( g ) aseptically combining the slurry of step ( d ) and the solution of step ( 0 to form a suspension and adjusting the ph , in a preferred embodiment , the present invention provides a process for preparing sterile ophthalmic suspension of brinzolamide comprising the steps of : ( b ) preparing a solution comprising tyloxopol , mannitol , sodium chloride and benzalkonium chloride , ( d ) aseptically combining the slurry of step ( a ) and the solution of step ( c ) to form a dispersion , ( f ) adding the sterile brinzolamide to autoclaved dispersion of step ( e ) to form the suspension and adjusting the ph , in another preferred embodiment , the present invention provides process for preparing sterile ophthalmic suspension of brinzolamide comprising the steps of : ( c ) combining the slurry of step ( a ) and step ( b ) and milling the said slurry , ( e ) preparing a solution of mannitol , sodium chloride and benzalkonium chloride in water , ( g ) aseptically combining the slurry of step ( d ) and the solution of step ( 0 to form a suspension and adjusting the ph , in another embodiment , the present invention also provides the use of brinzolamide ophthalmic suspension prepared by the process as described herein for treating glaucoma or ocular hypertension . the following examples further exemplify the invention and are not intended to limit the scope of the invention . the processing steps involved in manufacturing brinzolamide ophthalmic suspension given in example 1 are given below ; a ) carbomer was dispersed in water to form a slurry , b ) mannitol , sodium chloride , edetate disodium , tyloxopol and benzalkonium chloride was dissolved in water , c ) the solution of step ( i ) was filtered , d ) the slurry of step ( a ) and the solution of step ( b ) was combined to obtain a suspension , e ) the suspension of step ( d ) was sterilized by autoclave , f ) sterile brinzolamide was added to the dispersion of step ( e ) and the ph was adjusted using hydrochloride / sodium hydroxide , g ) the suspension of step ( f ) was homogenized and then filled in dispenser . the alternate processing steps involved in manufacturing brinzolamide ophthalmic suspension given in example 1 are given below : a ) tyloxapol was dispersed in water and then filtered , b ) brinzolamide was added to the dispersion of step ( a ), c ) carbomer was dispersed in water to form a slurry , d ) the dispersion of step ( b ) and the slurry of step ( c ) were combined to obtain a homigenised dispersion , e ) the dispersion of step ( d ) was milled and then sterilized by autoclave , f ) mannitol , sodium chloride , edetate disodium and benzalkonium chloride was dissolved in water , g ) the solution of step ( f ) was sterilized by autoclave , h ) combining the dispersion of step ( e ) and step ( g ) and homogenizing said dispersion and the ph was adjusted using hydrochloride / sodium hydroxide , i ) the suspension of step ( h ) was homogenized and then filled in dispenser . the alternate processing steps involved in manufacturing brinzolamide ophthalmic suspension given in example 1 are given below : a ) tyloxapol was dispersed in water and then filtered , b ) brinzolamide was added to the dispersion of step ( a ), c ) carbomer was dispersed in water to form a slurry , d ) the dispersion of step ( b ) and the slurry of step ( c ) were combined to obtain a homigenised dispersion , e ) the dispersion of step ( d ) was milled and then sterilized by autoclave , f ) mannitol , sodium chloride , edetate disodium and benzalkonium chloride was dissolved in water , g ) the solution of step ( f ) was filtered , h ) combining the dispersion of step ( e ) and step ( g ) and homogenizing said dispersion and the ph was adjusted using hydrochloride / sodium hydroxide , i ) the suspension of step ( h ) was homogenized and then filled in dispenser . the processing steps involved in manufacturing brinzolamide ophthalmic suspension as given in examples 2 to 4 is same as that of the process described in example 1 . the processing steps involved in manufacturing brinzolamide ophthalmic suspension are as set forth . a ) carbomer was dispersed in water to form a slurry , b ) mannitol , sodium chloride , optionally edetate disodium and / or tyloxopol and / or benzalkonium chloride was dissolved in water , c ) the solution of step ( i ) was filtered , d ) the slurry of step ( a ) and the solution of step ( b ) was combined to obtain a suspension , e ) the suspension of step ( d ) was sterilized by autoclave , f ) sterile brinzolamide was added to the dispersion of step ( e ) and the ph was adjusted using hydrochloride / sodium hydroxide , g ) the suspension of step ( f ) was homogenized and then filled in dispenser . the alternate processing steps involved in manufacturing brinzolamide ophthalmic suspension are given below : a ) tyloxapol was dispersed in water and then filtered , b ) brinzolamide was added to the dispersion of step ( a ), c ) carbomer was dispersed in water to form a slurry , d ) the dispersion of step ( b ) and the slurry of step ( c ) were combined to obtain a homigenised dispersion , e ) the dispersion of step ( d ) was milled and then sterilized by autoclave , mannitol , sodium chloride , optionally edetate disodium and / or benzalkonium chloride was dissolved in water , g ) the solution of step ( f ) was sterilized by autoclave , h ) combining the dispersion of step ( e ) and step ( g ) and homogenizing said dispersion and the ph was adjusted using hydrochloride / sodium hydroxide , i ) the suspension of step ( h ) was homogenized and then filled in dispenser . the alternate processing steps involved in manufacturing brinzolamide ophthalmic suspension are given below : a ) tyloxapol was dispersed in water and then filtered , b ) brinzolamide was added to the dispersion of step ( a ), c ) carbomer was dispersed in water to form a slurry , d ) the dispersion of step ( b ) and the slurry of step ( c ) were combined to obtain a homigenised dispersion , e ) the dispersion of step ( d ) was milled and then sterilized by autoclave , f ) mannitol , sodium chloride optionally edetate disodium and / or benzalkonium chloride was dissolved in water , g ) the solution of step ( f ) was filtered , h ) combining the dispersion of step ( e ) and step ( g ) and homogenizing said dispersion and the ph was adjusted using hydrochloride / sodium hydroxide , i ) the suspension of step ( h ) was homogenized and then filled in dispenser . the alternate processing steps involved in manufacturing brinzolamide ophthalmic suspension are given below : a ) brinzolamide was dispersed in water , b ) carbomer was dispersed in water to form a slurry , c ) the dispersion of step ( a ) and the slurry of step ( b ) were combined to obtain a homigenised dispersion , d ) the dispersion of step ( c ) was milled and then sterilized by autoclave , e ) mannitol , sodium chloride , optionally edetate disodium and / or benzalkonium chloride was dissolved in water , f ) the solution of step ( e ) was sterilized by autoclave , g ) combining the dispersion of step ( d ) and step ( f ) and homogenizing said dispersion and the ph was adjusted using hydrochloride / sodium hydroxide , h ) the suspension of step ( g ) was homogenized and then filled in dispenser . the alternate processing steps involved in manufacturing brinzolamide ophthalmic suspension are given below : a ) brinzolamide was dispersed in water , b ) carbomer was dispersed in water to form a slurry , c ) the dispersion of step ( a ) and the slurry of step ( b ) were combined to obtain a homigenised dispersion , d ) the dispersion of step ( c ) was milled and then sterilized by autoclave , e ) mannitol , sodium chloride , optionally edetate disodium and / or benzalkonium chloride was dissolved in water , f ) the solution of step ( e ) was filtered , g ) combining the dispersion of step ( d ) and step ( f ) and homogenizing said dispersion and the ph was adjusted using hydrochloride / sodium hydroxide , h ) the suspension of step ( g ) was homogenized and then filled in dispenser . the processing steps involved in manufacturing brinzolamide ophthalmic suspension given in example 1 are given below : h ) carbomer was dispersed in water to form a slurry . i ) mannitol , sodium chloride , edetate disodium , tyloxopol and benzalkonium chloride , timolol maleate was dissolved in water , j ) the solution of step ( i ) was filtered , k ) the slurry of step ( a ) and the solution of step ( b ) was combined to obtain a suspension , l ) the suspension of step ( d ) was sterilized by autoclave , m ) sterile brinzolamide was added to the dispersion of step ( e ) and the ph was adjusted using hydrochloride / sodium hydroxide , n ) the suspension of step ( f ) was homogenized and then filled in dispenser . the alternate processing steps involved in manufacturing brinzolamide ophthalmic suspension given in example 1 are given below : j ) tyloxapol was dispersed in water and then filtered , k ) brinzolamide was added to the dispersion of step ( a ), l ) carbomer was dispersed in water to form a slurry , m ) the dispersion of step ( b ) and the slurry of step ( c ) were combined to obtain a homigenised dispersion , n ) the dispersion of step ( d ) was milled and then sterilized by autoclave , o ) mannitol , sodium chloride , timolol maleate , edetate disodium and benzalkonium chloride was dissolved in water , p ) the solution of step ( f ) was sterilized by autoclave , q ) combining the dispersion of step ( e ) and step ( g ) and homogenizing said dispersion and the ph was adjusted using hydrochloride / sodium hydroxide , r ) the suspension of step ( h ) was homogenized and then filled in dispenser . the alternate processing steps involved in manufacturing brinzolamide ophthalmic suspension given in example 1 are given below : j ) tyloxapol was dispersed in water and then filtered , k ) brinzolamide was added to the dispersion of step ( a ), l ) carbomer was dispersed in water to form a slurry , m ) the dispersion of step ( b ) and the slurry of step ( c ) were combined to obtain a homigenised dispersion , n ) the dispersion of step ( d ) was milled and then sterilized by autoclave , o ) mannitol , sodium chloride , timolol maleate , edetate disodium and benzalkonium chloride was dissolved in water , p ) the solution of step ( f ) was filtered , q ) combining the dispersion of step ( e ) and step ( g ) and homogenizing said dispersion and the ph was adjusted using hydrochloride / sodium hydroxide , r ) the suspension of step ( h ) was homogenized and then filled in dispenser .
the present invention relates to a process for preparing sterile ophthalmic suspension of carbonic anhydrase inhibitor . more particularly , the present invention relates to a process for preparing sterile ophthalmic suspension of brinzolamide .