Background of the Invention

The present invention relates to enzyme- containing compositions and methods employing such enzyme- containing compositions for contact lens cleaning. More particularly, the invention relates to such enzyme- containing compositions and to contact lens cleaning methods employing enzyme-containing compositions which provide for deactivating the enzyme after the contact lens has been effectively enzymatically cleaned. The growth of the contact lens industry has led to a dramatic increase in the number of contact lens care systems. One goal of the lens care industry has been to simplify lens care systems while, at the same time, providing for effective, high quality care, and safe and comfortable wearing of the treated contact lenses.

In the normal course of wearing contact lenses, debris, such as tear film and proteinaceous, oily, sebaceous and related organic matter, has a tendency to deposit and build up on the lens surface. As part of the routine care of a contact lens, it should be cleaned to remove this debris. If this debris is not removed, the lens can become uncomfortable to wear and may even damage the eye.

One approach to removing debris buildup from contact lenses has been to subject the debris laden lenses to enzymatic action. For example, Karageozian U.S. Patent

3,910,296 discloses the use of proteases for cleaning contact lenses.

Ogata U.S. Patent 4,285,738 discloses the use of compositions comprising urea and/or an acid salt of guanidine, a reducing agent and a proteolytic enzyme, with or without additionally heating, to elf an contact lenses. Proteolytic enzymes disclosed include papain, trypsin, alpha-chymotrypsin, pronase p from S. griseus and proteinase from B. subtilis.

Anderson U.S. Patent 4,521,254 discloses methods and compositions for cleaning contact lenses comprising an endopeptidase such as bromelain and a carboxy peptidase enzyme.

Schaefer U.S. Patent 4,609,493 discloses contact lens cleaning compositions containing a proteolytic enzyme,- an anionic surfactant, a calcium chelating agent and urea. The calcium chelating agent is disclosed as a principal lens cleaning ingredient which does not significantly decrease the activity of the enzyme. Preferred enzymes are pancreatin and papain.

Ogunbiyi U.S. Patent 4,614,549 discloses methods for cleaning and thermally disinfecting contact lenses and deactivating the enzymes used for this process through the use of proteolytic enzymes in aqueous solutions which are heated to an elevated temperature between 60° C and 100° C. Ogunbiyi U.S. Patent 4,614,549 discloses the use of activator-free microbial-derived proteolytic enzymes as well as chelating agents such as salts of ethylene diamine tetraacetate (EDTA) to bind metal ions in solution such as calcium, which might otherwise react with lens protein and collect on lens surfaces.

Ogunbiyi U.S. Patent 4,690,773 discloses methods for cleaning contact lenses with an activator-free enzyme solution comprising an aqueous solution containing a protease derived from a Bacillus, Streptomyces or Aspergillus microorganism. The microbial proteases

disclosed require no additional activators or stabilizers and are not inhibited when in the presence of a chelating agent . This patent discloses that enzymes which are inhibited by chelating agents are generally unsatisfactory for use with contact lenses. Also, this patent discloses that proteases should be active at a pH range of from 5 to 8.5.

Huth et al U.S. Patent Reissue 32,672 discloses methods for simultaneous cleaning and disinfecting of contact lenses using a disinfecting amount of peroxide and peroxide-active enzymes. Neutral, acidic or alkaline enzymes, as well as mettallo-proteases, may be used.

Mowrey-McKee U.S. Patent 5,096,607 discloses methods for simultaneously cleaning and disinfecting contact lenses using polymeric quaternary ammonium salts or biguanides, a proteolytic enzyme and an aqueous system wherein the osmotic value is adjusted to a level which does not substantially inhibit the activity of the antimicrobial agent. This patent discloses that additional components, such as chelating and/or sequestering agents, may be added to or incorporated into the enzyme which do not substantially decrease the activity of the enzyme.

None of the aforementioned patents discloses methods or compositions to inactivate or deactivate cleaning enzymes via autolysis of the enzymes brought about by an autolysing agent.

An important concern relating to the enzymatic cleaning systems currently being employed is the need to remove the enzyme from the lens prior to placing the cleaned lens in the eye. Placing a lens contaminated with cleaning enzyme into the eye may be potentially detrimental to the eye. This potential problem, if any, is avoided currently by rinsing the contact lens free of cleaning enzyme prior to placing the cleaned lens in the

eye. However, this rinsing step may adversely impact user compliance since the user may consider such rinsing unnecessary and, as a result, place active enzyme in the eye. Additionally, in some instances, rinsing the contact lens free of cleaning enzyme may be insufficient to eliminate discomfort, irritation and detrimental ocular effects due to lens-bound active enzyme which may desorb or elute from the contact lens into the eye.

An additional concern relating to the enzymatic cleaning systems currently employed is that the lenses are often rubbed between the thumb and forefinger or in the palm of the hand, to remove the loosely adherent debris still remaining on the contact lens. Rubbing lenses often causes tearing and thus loss of the lens. The amount of debris remaining on the lenses is related to the cleaning efficiency of the enzyme composition which, in turn, is related to the concentration of enzyme employed. Current enzyme compositions must utilize lower concentrations of enzyme to avoid possible ocular surface damage if they are placed into the eyes. It would be advantageous to provide a system in which the lens is effectively cleaned without such rubbing.

Summary of the Invention

New contact lens treatment systems have been discovered. The present systems involve the use of enzymes, preferably faster and/or more efficient enzymes and enzyme-containing formulations, to clean contact lenses while reducing, and even eliminating, the risks of rubbing lenses and also placing active cleaning enzyme in the eye. Further, the present systems may not require rubbing and/or rinsing the cleaned contact lens prior to placing the lens in the eye. In other words, in one embodiment the cleaned contact lens is suitable to be taken directly from the enzyme-containing liquid medium,

in which the enzymatic cleaning takes place, and placed in the eye for safe and comfortable wear without risking damaging the lens or placing a damaging amount of active cleaning enzyme in the eye. The present invention takes advantage of autolysing agents which deactivate various contact lens cleaning enzymes. The term "autolysing agent" refers to those materials which are effective in effecting, i.e.,causing, promoting, and/or otherwise facilitating, autolysis, that is the autolytic destruction or self- destruction, of an enzyme. The presently useful autolysing agents may also facilitate the at least partial deactivation of an enzyme non-autolytically, for example, by facilitating a non-autolytic deactivation of the enzyme which renders it incapable of further enzymatic action. By controlling the autolysing agents to which the enzymes are exposed, effective enzymatic cleaning of the contact lens can be obtained, and then the enzymes can be effectively autolysed so as to render the enzymes inactive, and preferably substantially innocuous, or ophthalmically acceptable for example, in the environment present in the eye.

The present systems are relatively easy to manufacture, often include conventional and commercially available components, and are very easy to use, providing for good user compliance. In addition, the present systems can include components effective to disinfect contact lenses, for example, while the lenses are being enzymatically cleaned. Such "one step" systems for the cleaning and disinfecting of contact lenses are not only effective, but also are very convenient and easy to use, thus further enhancing user compliance.

As used herein, the term "ophthalmically acceptable" refers to a material or composition which is compatible with ocular tissue, that is, which does not

cause any significant or undue detrimental effect or effects when brought into contact with ocular tissue. Preferably, each of the individual components used in the present compositions and methods is' also compatible with the other components used in the present compositions and methods.

In one broad aspect of the present invention, compositions useful for cleaning contact lenses are provided and comprise an enzyme component and an autolysing agent. The enzyme component is present in an amount effective when released in a liquid medium to remove debris from a contact lens located in the liquid medium. The autolysing agent, which preferably is ophthalmically acceptable, when used in amounts effective to cause autolysis of the enzyme component, is present in an amount effective when released in the liquid medium to deactivate the enzyme component located in the liquid medium. A third component of the compositions of this invention can be a delayed release component which is associated with the autolysing agent in an amount sufficient to delay the action of the autolysing agent upon the enzyme component. In one embodiment, such compositions may be, and preferably are, structured so that the enzyme component is released in the liquid medium a period of time before the autolysing agent is released in the liquid medium. This period of time is sufficient to allow the enzyme component to effectively remove debris, preferably to completely remove at least one type of debris, from a contact lens which is introduced into the liquid medium before or at the same time the enzyme component is released in the liquid medium. Alternately, the enzyme component may be released in the liquid medium at about the same time as the autolysing agent. In this embodiment, the interaction/reaction between the autolysing agent and the enzyme component can take place

while the enzyme component is removing debris from the contact lens and is slow enough to allow sufficient lens cleaning, debris removal, to take place prior to or simultaneously with enzyme component deactivation. Using the compositions as described herein, one can remove the cleaned contact lens from the liquid medium after the autolysing agent has deactivated the enzyme component, and safely place the contact lens in the eye with or without intermediate rubbing and/or rinsing steps. More potent enzyme components and/or greater amounts of enzyme components than are conventionally employed to clean a contact lens can be satisfactorily and safely used in accordance with the present invention, thereby eliminating the need for a separate contact lens rubbing step. Amounts of enzyme component equal to at least about 200% or at least about 400% or more (based on enzymatic activity) of the amount of enzyme component conventionally employed may be used.

The present methods for cleaning contact lenses can employ compositions as described here. The present invention relates to a method for inactivating or deactivating an enzyme component used to remove debris from a contact lens comprising contacting the enzyme component with an autolysing agent in an amount effective to cause autolysis .of the enzyme component after the enzyme component has been used to remove debris from the contact lens. In one embodiment, such methods comprise introducing a contact lens into a liquid medium, and introducing a composition as described above, into the liquid medium. The contact lens is preferably introduced into the liquid medium at substantially the same time as the composition is introduced into the liquid medium. The present methods provide effectively cleaned contact lenses which may be placed in the eye directly from the liquid medium for safe and comfortable wear.

In one very useful embodiment, the liquid medium includes a disinfectant component in an amount effective to disinfect the contact lens located in the liquid medium. In this embodiment, the contact lens is both cleaned and disinfected. Such "one-step" cleaning and disinfecting systems are effective and easy for the contact lens wear to use.

Detailed Description of the Invention

The present invention can be used with all contact lenses such as conventional hard, soft, rigid gas permeable, and silicone lenses. The invention is preferably employed with soft lenses, such as those commonly referred to as hydrogel lenses prepared from monomers, such as hydroxyethylmethacrylate, vinylpyrrolidone, glycerylmethacrylate, methacrylic acid, methacrylic acid esters, and the like. Hydrogel lenses typically absorb significant amounts of water, such as in the range of about 38 to about 80 percent by weight or more. The present invention generally employs an effective amount of enzyme component to remove debris from a contact lens. Among the types of debris that form on a contact lens during normal use are protein-based debris, mucin-based debris, lipid-based debris and carbohydrate- based debris. One or more types of debris may be present on a single contact lens.

The specific amount of enzyme component employed depends on several factors including, for example, the particular enzyme or enzymes employed, the activity of the enzyme or enzymes, the purity of the enzyme, the amount and type of debris deposited on the lens, the desired soaking period, the nature and concentration of the disinfecting agent if any, the specific type of lenses, as well as other well known factors.

The liquid medium preferably should contain sufficient enzyme to provide between about 0.0001 to 0.5 Anson units of activity per single lens treatment, more preferably between 0.0010 and 0.05, and still more preferably between 0.0020 and 0.020, Anson units per single lens treatment, in 1 to 10 ml of liquid medium. The precise amount of enzyme on a weight per unit volume of liquid medium basis depends, for example, on the purity of the enzyme and may need to be finally determined on a lot-by-lot basis.

The autolysing agent is present in an amount effective, when released in the liquid medium containing the enzyme component, to deactivate the enzyme component. The autolysing agent is used effectively when its autolysing effect or action upon the enzyme component occurs after lapse of a period of time following placement of the enzyme component in contact with the contact lens to be cleaned. This delay allows the enzyme component to remove debris from the lens before the autolysing agent acts to effect the autolysis and deactivation, preferably the complete deactivation, of the enzyme component. Of course, the autolysing agent should be chosen to effect the autolysis and possibly otherwise deactivate the specific enzyme component being employed. One autolysing agent may be effective against one or more of certain enzymes while not being effective against other enzymes . Thus, it is important that the proper enzyme component/autolysing agent couple be chosen. In addition, the autolysing agent should be chosen so as to have no substantial detrimental effect on the lens being treated or on the eyes of the wearer of the treated contact lens .

Any suitable autolysing agent may be employed which is capable of effecting autolysis of the enzyme component . Preferred autolysing agents are those which have no detrimental effect upon ocular tissue when used

frequently, such as weekly or even daily, while exhibiting a high level of autolysis activity with respect to the enzyme component being employed. The autolysing agent is preferably soluble or at least dispersible in the enzyme component-containing liquid medium. In a particularly useful embodiment, the autolysing agent comprises a material which is selected from the group consisting of alkali metal and alkaline earth metal salts of alkyl sulfates, preferably having about 6 to about 20 or more carbon atoms per molecule, alcohols having up to about 6 carbon atoms per molecule, aromatic quaternary ammonium salts, preferably having about 6 to about 15 or more carbon atoms per molecule, cross-linked acrylic acid polymers, and mixtures thereof. Specific materials useful as autolysing herein are sodium, potassium, and calcium dodecyl sulfates, ethyl alcohol and isopropyl alcohol, benzalkonium chloride, and water-swellable cross-linked acrylic acid polymers, such as those sold by B. F.

Goodrich under the trademark Carbopol, for example, Carbopol 1382 resin.

In a preferred embodiment, the enzyme component may be present in the liquid medium into which is introduced the contact lens to be cleaned. The autolysing agent can be introduced into this liquid medium at the same time or after the contact lens is introduced into the liquid medium. The autolysing agent does, over time, effect the autolysis, and possibly otherwise affect, the enzyme component to deactivate, preferably substantially completely deactivate, the enzyme component. The amount of autolysing agent used in accordance with the present invention varies widely and depends, for example, on the specific type and amount of enzyme component being employed, on the specific autolysing agent being employed, on the amount of time during which the enzyme component is to be deactivated and the like

factors. In general, the amount of autolysing agent used is that amount effective to autolyse all of the enzyme component present in a reasonable time, for example, in the range of about 1 hour or less to about 4 to about 6 hours or more, after the autolysing agent is released in a liquid medium containing the enzyme component. Excessive amounts of autolysing agents should be avoided since this is wasteful and unnecessary and may have detrimental effects, for example, on the wearer of the cleaned contact lens. The amount of autolysing agent employed is preferably from about 100% to no more than about 200% or about 300% of that amount needed to completely autolyse all of the enzyme component present in the liquid medium in a reasonable time. An enzyme component can be provided in an amount effective to at least facilitate removing deposit material from the contact lens. Types of deposit material or debris which may be deposited on the lens include proteins, lipids, and carbohydrate-based or mucin-based debris. One or more types of debris may be present on a given lens.

Substantially any enzyme component which is effective to remove one or more types of deposit material from a contact lens can be utilized in accordance with the present invention. The enzyme employed may be selected from peroxide-active enzymes which are conventionally employed in the enzymatic cleaning of contact lenses. For example, many of the enzymes disclosed in Huth et al U.S.

Reissue Patent 32,672 and Karageozian et al U.S. Patent 3,910,296 are useful in the present invention. These patents are incorporated in their entirety by reference herein. Among the useful enzymes are those selected from proteolytic enzymes, lipases and mixtures thereof.

Preferred proteolytic enzymes are those which are

substantially free of sulfhydryl groups or disulfide bonds .

A more preferred group of proteolytic enzymes are the serine proteases, particularly those derived from Bacillus and Streptomvces bacteria and Aspergillus molds. Within this grouping, the still more preferred enzymes are the derived alkaline proteases generically called subtilisin enzymes. Reference is made to Keay, L., Moser, P.W. and Wildi, B.S., "Proteases of the Genus Bacillus". II. Alkaline Proteases, "Biotechnology and Bioengineering, Vol. XII, pp. 213-249 (1970, March) and Keay, . and Moser, P.W., "Differentiation of Alkaline Proteases from Bacillus Species" Biochemical and Biophysical Research Comm. , Vol. 34, No. 5, pp. 600-604 (1969) . The subtilisin enzymes are broken down into two subclasses, subtilisin A and subtilisin B. In the subtilisin A grouping are enzymes derived from such species are B. subtilis, B. licheniformis and B. pumilis. Organisms in this sub-class produce little or no neutral protease or amylase. The subtilisin B sub-class is made up of enzymes from such organisms as B. subtilis. B. subtilis var. amylosacchariticus, B. amyloliquefaciens and B. subtilis NRRL B3411. These organisms produce neutral proteases and amylases on a level about comparable to their alkaline protease production. One or more enzymes from the subtilisin A sub-class are particularly useful. In addition other preferred enzymes are, for example, pancreatin, trypsin, collagenase, keratinase, carboxylase, aminopeptidase, elastase, and aspergillo- peptidase A and B, pronase E (from S. griseus) and dispase (from Bacillus polv vxa) .

Various acid-acting enzymes may be employed. Preferably, the enzyme component is effective at a pH in the range of about 2 to about 5, more preferably about 3 to about 5. Specific examples of acid-acting enzymes

which may be employed in the present invention include pepsin, gastricsin, chymosin (rennin) , cathepsin D, genetically engineered enzymes, such as subtilisin, with acid pH activity profiles, rhizopus chinensis acid protease, protease B isolated from Scytalidium lignicolum

(ATCC 24568) and entinus edodes TMI-563, acid proteases isolated from Ganoderna lucidum IFO 4912, Pleurotus cornucopia, Pleurotus astreatus IFO 7051, Flammulina velutipes IFO 7046 and Lintinus edodes IFO 4902, acid proteases isolated from cells and in the culture medium of

Solfolobus acidocaldarius (thermopsin) , Sulfolobus solataricus and Thermoplasma acidophilim, penicillium requefor i acid protease, fungal acid proteases such as penicillopepsin from Penicillium anthinellum, aspergillopeptidase A from Aspergillus saitoi, endothia acid protease from Endothia parasitin, mucor rennins from Mucor michei, and the like and mixtures thereof.

The enzyme component may be employed in liquid or solid form. The enzyme component may be provided in a solid form such as tablets, pills, granules and the like, which is introduced into a liquid medium.

Additional components may be added to or incorporated into the enzyme component-containing solid and/or the liquid medium. For example, components such as effervescing agents, stabilizers, buffering agents, chelating and/or sequestering agents, coloring agents or indicators, tonicity adjusting agents, surfactants and the like can be employed. In addition, binders, lubricants, carriers, and other excipients normally used in producing tablets may be used when enzyme componen -containing tablets are employed.

Effervescing agents are typically employed when the enzyme component is provided in solid form. Examples of suitable effervescing agents include tartaric or citric

acid used in combination with a suitable alkali metal salt such as sodium carbonate.

Examples of suitable buffering agents which may be incorporated into an enzyme component-containing tablet or the liquid medium include alkali metal salts such as potassium or sodium carbonates, acetates, borates, phosphates, citrates and hydroxides, and weak acids such as acetic acid and boric acid. Preferred buffering agents are alkali metal borates such as sodium borate and potassium borate. Additionally, other pH adjusting agents may be employed, such as inorganic acids. For example, hydrogen chloride may be employed in concentrations suitable for ophthalmic uses. Generally, buffering agents are present in amounts from about 0.01 to about 2.5% (w/v) and preferably, from about 0.2 to about 1.5% (w/v) , of the liquid medium.

Any suitable colorant component and/or indicator component may be included in the present compositions, for example, to indicate the presence and/or the absence of oxidative disinfectants, such as, hydrogen peroxide. A particularly useful indicator component is cyano cobalamine. Of course, other conventional colorant components/indicator components may be employed.

The tonicity adjusting agent which may be a component of the liquid medium and may optionally be incorporated into an enzyme component-containing tablet is employed to adjust the osmotic value of the liquid medium. Suitable surfactants can be either cationic, anionic, nonionic or amphoteric. Preferred surfactants are neutral or nonionic surfactants which may be present in amounts up to 5% (w/v) . Examples of suitable surfactants include polyethylene glycol esters of fatty acids, polyoxypropylene ethers of C ₁₂ -C _lg alkanes and

polyoxyethylene, polyoxypropylene block copolymers of ethylene diamine (e.e., poloxamine) .

The binders and lubricants for enzyme tableting purposes and other excipients normally used for producing powders, tablets and the like, may be incorporated into enzyme component-containing tablet formulations.

In a very useful embodiment, the autolysing agent is present in a delayed release form. Thus, the autolysing agent may be introduced into the liquid medium at the same time (and as part of the same item or items which include the enzyme component) as the enzyme component is introduced into the liquid medium. However, the autolysing agent is released in the liquid medium after the enzyme component is so released. The release of the autolysing agent is preferably delayed for a period of time sufficient to allow the released enzyme component to remove, more preferably completely remove, at least one type of debris from a contact lens present in the liquid medium. Such sufficient time is preferably within about 6 hours, for example, in the range of about 1 minute to about 6 hours, more preferably within about 4 hours, for example, in the range of about 2 minutes to about 4 hours. Although multi-layered (including core and coating layering) tablets or pills are preferred, the delayed release forms of the pres.ent compositions can be present in any other suitable item or items, such as masses of powders, granules and the like. Delayed release technology is well known in the art as exemplified by the text Controlled Drug Delivery, 2nd Ed. , Joseph R. Robinson & Vincent H.L. Lee, Eds., Marcel Dekker, Inc., New York, 1987.

Items which release their ingredients in a sequential, time delayed manner are well known and can be produced using conventional technology. Therefore, a

detailed description of such items and such production technology is not presented here.

In one useful embodiment, a core tablet is-formed using conventional tableting equipment. A solution containing the delayed release component is applied, e.g. , sprayed, onto the core tablet using conventional coating equipment, such as film coating pans or fluid beds. Coating pan equipment is available from Dria of West Germany, Thomas Engineering, Vector Corporation, and Key Industries in the U.S. Fluid bed equipment is available from Glatt Air Techniques, Vector Corporation, and Aeromatic, as well as other companies. Using appropriate coating parameters, which are dependent on, for example, the specific composition of the delayed release component- containing solution, the equipment used and core tablet size, an appropriate amount of delayed release component is applied to the core table that allows the desired delay release time.

Any suitable delayed release component or combination of delayed release components may be employed, provided that such component or components function as described herein and have no substantial detrimental effect on components used to treat the lens, on the lens being treated and on the human wearing the treated lens. The delayed release component is preferably at least partially, more preferably completely, water soluble. The delayed release component preferably comprises a major amount of at least one polymeric material . Examples of useful delayed release components include, but are not limited to, soluble cellulose ethers such as methylceUulose , methylhydroxypropyleellulose , methylhydroxyethylcellulose, hydroxypropylcellulose, hydroxyethyleellulose and sodium carboxymethycelluloses; cellulose esters such as cellulose acetate phthalate and hydroxypropylmethylcellulose phthalate; polymers derived

from at least one of acrylic acid, acrylic acid esters, methacrylic acid and methacrylic acid esters such as methacrylic acid-methyl methacrylate copolymer (for example that sold by Rohm Phar a under the tradename Eudragit L 100) and methacrylic acid-ethyl acrylate copolymers (for example that sold by Rohm Pharma under the trademark Eudragit L 30D) ; polymers derived from methyl vinyl ether and maleic acid anhydride ,- polyvinylpyrrolidone; polyvinyl alcohols and the like and mixtures thereof. The delayed release component is advantageously used in conjunction with a liquid medium, and is used in an amount effective to delay the action of autolysing agent for a period of time after the addition of the autolysing agent to the liquid medium. The liquid medium useful in practicing the present invention is preferably aqueous-based. The liquid medium can include . disinfectant component. Such disinfectant component is present in a disinfecting amount, in particular in an amount effective to disinfect a contact lens.

A disinfecting amount of disinfectant component means such amount as reduces the microbial burden to an acceptable level within a reasonable period of time, such as four hours or less. The disinfectant component may be oxidative or non-oxidative. Particularly useful oxidative disinfectant components are hydrogen peroxide or one or more other peroxy-containing compounds, for example, one or more other peroxides. For hydrogen peroxide, a 0.5% (w/v) concentration, for example, in an aqueous liquid medium, is often effective as a disinfectant component. It is preferred to use at least about 1.0% or about 2.0% (w/v) hydrogen peroxide, which concentrations reduce the disinfecting time over that of the 0.5% (w/v) peroxide

concentration. No upper limit is placed on the amount of hydrogen peroxide which can be used in this invention except as limited in that the disinfectant component should have no substantial detrimental effect on the contact lens being treated or on the eye of the wearer of the treated contact lens . An aqueous solution containing about 3% (w/v) hydrogen peroxide is very useful.

So far as other peroxides are concerned, they should be used in effective disinfecting concentrations. When an oxidative disinfectant is used in the present invention, a reducing or neutralizing component in an amount sufficient to chemically reduce or neutralize substantially all of the oxidative disinfectant, for example, hydrogen peroxide, present is employed. Such reducing or neutralizing components are preferably incorporated into the enzyme component- containing tablet. The reducing agent is generally any non- oxic reducing agent. Reducing components include SH (group) -containing water-soluble lower alcohols, organic amines and salts thereof, amino acids and di-or tripeptides, e.g., cysteine hydrochloride ethyl ester, glutathione, homocysteine, carbamoyl cysteine, cysteinylglycine, 2-mercaptopropionic acid, 2- mercaptopropionylglycine , 2 -mereaptoethylamine hydrochloride, cysteine, n-acetylcysteine, beta mercaptoethanol, cysteine hydrochloride, dithiothreitol, dithioerythritol, sodium bisulfate, sodium metabisulfite, thio urea, sulfites, pyrosulfites and dithionites such as the alkali metal salts or alkaline earth metal salts of sulfurous acid, pyrosulfurous acid and dithionious acid, e.g., lithium, sodium, calcium and magnesium salts and mixtures thereof. The thiols are preferred, with N- acetylcysteine being particularly useful .

In general, the reducing component is used in amounts in the range of about 0.5% to about 10% (w/v) of the liquid medium.

In one embodiment, all or a portion of the reducing component is replaced by a peroxidase enzyme component, in particular catalase, which acts to catalyze the neutralization or decomposition of the oxidative disinfectant component, such as hydrogen peroxide. Such peroxidase enzyme component is included, for example, in the enzyme component-containing core tablet, in an amount effective to, together with the reducing component, if any, destroy or cause the destruction of all the oxidative disinfectant component present in the liquid medium. Some excess peroxidase enzyme component may be advantageously used to increase the rate at which the oxidative disinfectant component is destroyed.

As used herein, non-oxidative disinfectant components are non-oxidative organic chemicals which derive their antimicrobial activity through a chemical or physiochemical interaction with the microbes or microorganisms. Suitable non-oxidative disinfectant components are those generally employed in ophthalmic applications and include, but are not limited to, quaternary ammonium salts used in ophthalmic applications such as poly[ (dimethylimino) -2-butene-l,4-diyl chloride, alpha-(4-tris (2-hydroxyethyl) ammonium-2-butenyl-w-tris (2- hydroxyethyl) ammonium] -dichloride (chemical registry number 75345-27-6, available under the trademark polyquaternium 1 ^® from ONYX Corporation) , benzalkonium halides, and biguanides such as salts of alexidine, alexidine-free base, salts of chlorhexidine, hexamethylene biguanides and their polymers, antimicrobial polypeptides, and the like and mixtures thereof .

The salts of alexidine and chlorhexidine can be either organic or inorganic and are typically disinfecting

gluconates, nitrates, acetates, phosphates, sulphates, halides and the like. Generally, the hexamethylene biguanide polymers, also referred to as polyaminopropyl biguanide (PAPB) , have molecular weights of up to about 100,000. Such compounds are known and are disclosed in U.S. Patent No. 4,758,595.

Another class of disinfectant components which meet the foregoing criteria when detoxified are compounds having the following formula:

wherein R is an alkyl or alkenyl group having 12-20 carbon atoms and preferably a myristyl or tallow group, i.e., composed of mixtures of -CμH _j g and C ₁₄ H ₂₉ (myristyl) or Cι ₇ H ₃₄ and -C _l7 H ₃₅ (tallow) ; and R _t , R ₂ , and R ₃ are the same or different and represent alkyl groups having 1-3 carbon atoms. This disinfectant component should be used together with a detoxifying amount of a non-toxic component, preferably selected from water soluble polyhydroxyethyl methacrylate, carbonxymethylcellulose, non-ionic surfactants such as polyoxyethylene sorbitan fatty acid esters and polyexethylene ethers, polyvinylpyrrolidone, polyvinyl alcohol , hydroxypropylmethylcellulose, and the like and mixtures thereof.

The amount of the detoxifying component which is used in connection with a disinfectant component disinfecting of Formula A varies widely, for example, in the range of about 0.0001 to about 2.0%, preferably about

0.04 to about 0.4%, (w/v) of the liquid medium.

Another class of disinfectant components are the quaternary ammonium substituted polypeptides, such as

those which are based on a collagen hydrolysate of relatively low molecular weight. A particularly useful quaternary ammonium substituent is the lauryl trimethyl ammonium chloride group. The quaternary ammonium substituted polypeptides preferably have molecular weights in the range of about 500 to about 5000. One specific example is that sold under the trademark Croquat L by Croda, Inc.

Yet another class of disinfectant components are the ophthalmically acceptable quaternary ammonium polymers selected from ionene polymers containing an oxygen atom covalently bonded to two carbon atoms and mixtures thereof. Such polymers are described in Dziabo et al U.S. Patent 5,145,643 which is incorporated in its entirety by reference herein.

A specific example is poly [oxyethylene (dimethyliminio) ethylene - (dimethyliminio) ethylene dichloride] , sold under the trademark WSCP by Buckman Laboratories, Inc. Other disinfecting agents include dodecyl- dimethyl- (2-phenoxyethyl) -ammonium bromide.

Examples of ophthalmically acceptable anions which may be included in the ionic disinfectant components useful in the present invention include chloride (Cl) , bromide, iodide, bisulfate, phosphate, acid phosphate, nitrate, acetate, maleate, fumarate, oxalate, lactate, tartrate, citrate, gluconate, saccharate, p-toluene sulfonate and the like.

The non-oxidative disinfectant components useful in the present invention are preferably present in the liquid medium in concentrations in the range of about 0.00001% to about 0.01% (w/v) . The more preferred range for polyguads (e.g., poly-quaternium-1) and biguanides is 0.00005% to about 0.0015% (w/v) and for quaternary ammonium substituted polypeptides (e.g., Croquat L) and

polymers (e.g. WSCP) is in the range of about 0.003% to 0.015% (w/v) .

More preferably the agent is present in the working solution at an ophthalmically safe concentration such that the user can rinse the lens with the solution and thereafter directly place the lens in the eye.

For purposes of the present invention an aqueous solution containing about 0.00001% to about 0.005% (w/v) of a non-oxidative disinfectant component may be used as a multipurpose solution. That is, the solution (liquid medium) can be used for disinfection, cleaning (together with the enzyme component) , storage and rinsing. Thus, by using the methodology of the present invention, the user only needs to have the enzyme component/deactivator component couple, for example, in the form of a delayed release tablet, and a single solution, the multi-purpose solution noted above or a single multi-purpose solution which contains an acid-acting protease which is neutralized by tears or fluids in the eye. There is no longer a need to rub and rinse the cleaned lens or to use a separate saline solution.

During practice of this invention, the enzyme component is in a liquid medium, typically about 1 to about 10 ml of liquid medium. The liquid medium may be isotonic, hypotonic or hypertonic, and may include an effective amount of a disinfectant component. The contact lens to be treated is preferably introduced into the liquid medium at the same time the enzyme component- containing formulation is so introduced if the enzyme component is not already present in the liquid medium. The contact lens/liquid medium contacting occurs at conditions effective to obtain the desired beneficial cleaning of the contact lens or cleaning and disinfecting of the contact lens. If the liquid medium is aqueous- based, as is preferred, contacting temperatures in the

range of about 0°C to about 100°C are preferred, with temperatures in the range of about 10°C to about 60°C being more preferred and temperatures in the range of about 15°C to about 40°C being still more preferred. Contact lens/liquid medium contacting at ambient temperature is very convenient and useful. Preferably, the cleaning contacting takes less than about eight hours, with about 1 to about 6 hours being more preferred.

Preferably, the lens is removed from the liquid medium and placed directly into the eye without the need for separate rubbing and rinsing steps. Alternately, the lens can be rinsed with a buffered saline solution, or with a liquid medium having the same composition as that used above (without enzyme) , prior to insertion into the eye.

It is most convenient to formulate the enzyme component, autolysing agent and other dry components as a powder or tablet structured for delayed or sequential release of components, as described herein. The contact lens may already be in the liquid medium when the enzyme component/autolysing agent is introduced.

If the autolysing agent is normally a liquid, such as for example ethyl alcohol, a solid material particulate, can be used to absorb the liquid to form a paste or powder, which can in turn be coated by the delayed release component to encapsulate the liquid autolysing agent. Alternately, the autolysing agent can be included in a second liquid medium or diluent, e.g., water, which is added to the enzyme component containing liquid medium when it is desired to autolyse the enzyme component. The autolysing agent-containing liquid can be added in the form of a liquid filled capsule which dissolves after a period of time to release the autolysing agent.

The following non-limiting examples illustrate certain embodiments of the present invention.

EXAMPLE 1

A quantity of 1 to 2 mg of subtilisin is dissolved in 1 ml of deionized water. A solution of sodium dodecyl sulfate in 1 ml of deionized water in a concentration of 20 % v/v is also prepared. The two solutions are added together and allowed to react for 10 minutes at 45°C. A control is prepared as above except that no sodium dodecyl sulfate is added.

After the ten minute period, phenylmethylsulfonyl fluoride is added to prevent further autolysis of the subtilisin enzyme component.

Thirty minutes after the initial mixing of subtilisin and sodium dodecyl sulfate, a 2% (w/v) solution of sodium dodecyl sulfate sample buffer is added in a 1:1 ratio to the test sample, and incubated at 85°C for 10 minutes. The sample is then loaded onto a 14% tris- glycine gel and run on a Novex electrophoresis system at 125 V for approximately 100 minutes.

Results of ^• the gel electrophoresis show no subtilisin bands in the gel, indicating complete autolysis of the enzyme component.

EXAMPLE 2 Example 1 is repeated using a 20% v/v solution of ethyl alcohol instead of the sodium dodecyl sulfate solution.

Results of the gel electrophoresis show no subtilisin bands in the gel, indicating complete autolysis of the enzyme component.

EXAMPLE 3 Example 1 is repeated using a 20% v/v solution of benzalkonium chloride instead of the sodium dodecyl sulfate solution. Results of the gel electrophoresis show no subtilisin bands in the gel, indicating complete autolysis of the enzyme component .

EXAMPLE 4 Example 1 is repeated using a 20% w/v solution of Carbopol 1382, a water-swellable cross-linked acrylic acid polymer instead of the sodium dodecyl sulfate solution.

Results of the gel electrophoresis show no subtilisin bands in the gel, indicating complete autolysis of the enzyme component .

EXAMPLE 5

This Example illustrates the specificity of autolysis produced by a number of autolysis candidates which have been evaluated.

The procedure of Example 1 is followed except that the sodium dodecyl sulfate is omitted and the following autolysis candidates substituted in its place: a) 1 - Decanesulfonic acid b) 1 - Heptanesulfonic acid c) 3 - [ (3-cholamidopropyl ) -dimethylammonio] - 2 - hydroxy-1-propanesulfonate d) Launic acid e) Sorbitan monolaurate f) Triton 770 surfactant g) Triton 0S44 surfactant h) octoxynol i) Calbiochem Zwittergent detergent

TABLE 1 Autolysis Action on Subtilisin A Enzyme

Autolysis Agent Candidate Autolysis

Ac ivi y

Sodium dodecyl sulfate, Ex. 1 Yes Ethyl alcohol, Ex. 2 Yes

Benzalkonium chloride, Ex. 3 Yes

Carbopol 1382, Ex. 4 Yes

1 - Decanesulfonic acid, Ex. 5a No

1 - Heptanesulfonic acid No 3- [ (3-cholamidopropyl) - No dimethylammonio] -2-hydroxy-1- propanesulfonate

Launic acid No

Sorbitan monolaurate No Triton 770 surfactant No

Triton 0S 4 surfactant No

Octoxynol No

Calbiochem Zwittergent No detergent

EXAMPLE 6

A layered tablet is prepared using conventional techniques and has the following composition:

Core

Crystaline catalase 520 activity units Cyano cobalamine 0.085 mg

Polyethylene glycol 3350 1.05 mg

Sodium chloride 89.4 mg

Sodium phosphate dibasic 12.5 mg (anhydrous) Sodium phosphate 1.0 mg monobasic monohydrate

Carbipol 1382 5 mg

Core Coating

Subtilisin A 0.0075 Anson Units

This tablet is introduced into 10 ml of a conventional aqueous solution containing 3% (w/v) of hydrogen peroxide. A debris laden contact lens is introduced into the solution at the same time. Very quickly, the Subtilisin A enzyme is released into the solution and effectively removes debris from the contact lens. The hydrogen peroxide in the solution also effectively disinfects the contact lens. After about 40 minutes, the core is released in the solution. The catalase in the core is effective to cause the destruction of all the hydrogen peroxide in the solution. Sodium dodecyl sulfate is effective to effect the autolysis of the Subtilisin A enzyme so as to substantially completely deactivate the Subtilisin A.

The cleaned and disinfected contact lens can be removed from the solution and placed directly in the eye for safe and comfortable wear. Alternately and preferably, the cleaned and disinfected contact lens can be rinsed with a conventional buffered saline solution before being placed in the eye for safe and comfortable wear.

EXAMPLE 7 Core

Conventional sugar-based filler(Di-Pac) 40 mg Polyvinylpyrrolidone 4 mg

Polyethylene glycol 3350 4 mg

Carbopol 1382 10 mg Core Coating

Hydroxypropylmethylcellulose 2 mg

Outer Layer

Subtilisin A .0017 Anson Units

The following solution is prepared:

Polyaminopropyl biguanide, w/v% 0.0001

Sodium chloride, w/v% 0.37

TRIS ⁽¹ \ w/v% 1.2 Nonionic surfactant ⁽²⁾ , w/v% 0.025

Purified water, USP QS

(1) Tromethamine, otherwise known as

2-amino-2-hydroxy methyl-1, 3-propanediol

(2) A nonionic surfactant containing oxyethylated tertiary octylphenol formaldehyde polymer and sold under the trademark Tyloxapol by Ruger.

Hydrochloric acid is added to the solution to give a pH of about 7.5. - The above-noted tablet and a debris laden contact lens (in a lens holder) are introduced into 1.8 ml of the above-noted solution at the same time. Upon being introduced into the solution, the Subtilisin A is quickly released in the solution and effectively removed debris from the contact lens. In addition, the contact lens is being effectively disinfected by the solution. After about 1 hour, the core is released in the solution. The ethyl alcohol is effective to substantially completely deactivate the Subtilisin A. The contact lens is left in the solution for an additional 3 hours to complete disinfecting the lens.

The cleaned and disinfected contact lens can be removed from the composition and placed directly in the eye for safe and comfortable wear. Alternately, the cleaned and disinfected contact lens can be rinsed with a conventional buffered saline solution or the above polyaminopropyl biguanide-containing solution before being placed in the eye for safe and comfortable wear.

While this invention has been described with respect to various specific examples and embodiments, it

is to be understood that the invention is not limited thereto and that it can be variously practiced within the scope of the following claims.