CA2126093A1 - Composition for irrigating intraocular tissues and maintaining mydriasis during intraocular surgery - Google Patents

Abstract

An improved pharmaceutical composition useful in ophthalmic surgery is described. The composition includes a mydriatic agent, such as epinephrine in an acidic solution. The acidic solution preferably also contains glutathione. The composition is preferably formulated as a two-part solution, with the mydriatic agent being included in a relatively small volume, acid solution, and one or more electrolytes being included in a neutral, buffered solution having a relatively large volume.

Description

2 PCI~/US93/09912 2~2Ç~U(~t~

COMPOSITION FOR IRRIGATING INTRAOCULAR TISSUES
AND
MAINTAINING MYDRlASIS DURIN(;~ INTRAOCULAR SURGERY

Cross Reference to Related A~lica~ion(~):

1 he present applicadon is a con~nuadon~ part of United States Patent A.pplicati~n Serial No. 071964,327 f;led October 21, 1992.

13ack~Eo~Q Inven~ion:
s 1. Field Qf the Inventiop The p~esent invention relates to the field of intraocular surgery. More par~cularly, the ~nvenhon ~elates to a soludon which perfoIms the dual functions of:
(1) maintaining mydriasis, and (2) maintaining dle integIi~, stability, and func~on of ocula~
dssues, duIing invasiYe intraocular surg~cal procedur~s.
2. scussion Qf ~at~r~
Ihe ~QW~ of ~ew surgical techniques and associated products over d~e past decade has been quite rema~kable. For example, c~Jara~t surgeIy, which is a ve~y delicate op~a~on ~volving Ieplacement of the natural crystallin lens o~ ~e human eye with an ar~lcial lens, was previously consid~red to be a major surgical pr~cedure requiring lS hospitalization of the pa~ent and a Sigl~ifiCallt recovery period, but today this procedure is routinely per~o~med on an out-pa~ent basis and enables vision to be res~ored almost ~nmediately. Similar advancements have been achieved in other a~eas of ophthalmic surgery. These remarkable advancements are attributable tO various factors, including improved equipment for perfoIming the surgenes, improved surgical techniques developed by innova~ve surgeons, an~ improved phannaceutical products which facilitate successful surgery by minimizing dle risks of damaging sensi~ive, irreplaceable ocular ~ssue during surgery. The present invention is directed to a further improvement in one such `t~ 2 phannaceutical product, a solution for iITigating ocular tissue during intraocular surgerv Such solutions are discussed in United States Patent No. 4,550,022; the entire contents of that patent are hereby incorporated in the present specification by reference. The importance of such solutions to ophthalmic medicine is explained in dle '022 patent. The relevant s por~ons of that explanadon are repea~ed below.
Any scission into the human body is detrirnental to the human body and invariably results in cell loss. The need to keep cell loss to a minimuJTI is par~cularly crucial d~ing any surgical p~ocedure perfonned on delicate and irreplaceable tissues, such as the tissues of the eye, nerves, etc.
o ~he comea of the eye is compnsed of five layers: epithelium, Bowman's membrane, stroma, Decemet's membrane, and endothelium. The endothelium layer is pa~icularly vulnerable to trauma as the endothelial cells are infrequently, if ever, replaced as a normal process in the adult life. The endo~elium is principally responsible for the maintenance of the proper state of hydration of the stromal layer. The stromal layer has a tendency to ~s imbibe fluid, a tendency which is counter-balanced by outward fluid ~anspo¢t ~a the endothelium. If the proper fluid balance is not maintained in the stromal layer, the comea thickens and the characteristic transparency of the cornea is lost. Accordi.qgly, cell loss or damage in the end~thelial layer will result in decreased vision. Pailure of the endo~elium to pe~f~n its fluid transport function for short p~riods of time will ~esult in coqneal tbicke~ing and visual clouding. Because of the in~portance of, and ~e vulnerability of, the endothelial layer, it is necessaly during eye surgery, such as ca~a~act and re~nal surgery or corneal tran~plants, to m~ke provisions for ~e protecdon of the e~do~elial cells.
A signif;cant fact~r causing cell loss d~g dssue scission is the traumatic change in en~nment expenenced by the intemal oells. E~pos~e to the a~nosphere presen~s a far 2s different enviroDment for the cells than is provided by ~e natural fluidsin which dley are bathed. To simulate the natural cellular envir~nment and thereby prevent cell clamage, exposed tissue dwing surgery is frequently irrigated in solutions which attempt to approximate natural body fluids. The value of bathing eye tissue dunng surgery to prevent cell damage has long been recognized. For internal ocular tissues, such as the endothelium, the aqueous bumor is the natural bathing fluid and, hence, an ophthalmic i~igatàng solution intended to protect the endotheliun~ should as closely as possible resemble the aqueous humor.

WO 94/08602 2 1 2 ~ g 3 PCr/US93/09912 Of pnmary concem in a tissue irrigating solution is that the osmolality o~ the solution be generally isotonic with cellular fluids so as to maintain equal osmotic pressure within and without the cell membranes. To this end, one of the early ophthalmic irrigadng solutions was isotonic (0.9%) saline. However, as has long been recognized, isotonic saline is quite inadequate as an ophthahnic irrigating soludon and has been sho vn to result in endothelial cell s velling, cell damage, and consequent coQneal clouding.
Because of the inadequacy of isotonic saline, various alternative electrolyte solutions have been proposed as ophthalmic imgating solutions in attempts to provide solutions which more closely resemble the aqueous humor and prevent cell damagc and corneal clouding.
Standard electrolyte soludons primarily intended for injection soludons, such as Ringer's soludon and lac~ed Ringer's soludon, have been used as ophthalmic ilrigating solutions because of their wide availability as sterile solutions.
A solution intended for ophthalmic i~Tigadon known as "bahnced salt solution" has also been develaped Balanced salt solution contains the essential ions, calcium, sodium, IS potassium, magnesium and chloride in generally optimal concentrations for ocular tissue, and has an acetale-citrate buf~er system which is compatiblc with divalent calcium and magnesium ions.
The various electrolyte solutions used for ophd~almic i~igation have been improvcments over nnal saline by providing necessaty ions in addition tO Na~ and Cl as provided by isotonic saline. Mg+~ is an important cofactor for adenosine ~iphosphatase, an enzyme which plays an important role in mediating ~e fluid transp~rt pump in dle eye. Ca~
is necess~r to m~intain the endothelial junctioD. K+ is a~ important factor in many biochemical processes, and d~e fluid transport pump of ~e endothelium requuIes a proper Na+/l~+ ra~o.
2s D~ing eye surgery and parPcularly during surgery which requires extended periods of dme, p~oper electroly~c balance alone ~s insufficient to retain nonnal corneal ~hicknèss.
To maintain proper corneal thickness and prevent cell ~nage, an irrigating solution in addition to electrolytic balance must provide metabolic support and must pardcularly provide factors needed for the enzyme-mediated Na~ pump system through which excess fluid is removed from the s~oma To incorporate factors necessary for sustained metabolism by endothelial cells, glutatbione-bicarbonate-Ringers soludon ("GBR") was developed in which NaH~03, wo g4/08602 . Pcr/uss3/ossl2 ,5i3~ 4 glutathi~he, dextrose and adenosine (an optional ingredient) are added to Ringer s solu~on.
Bicarbonate, dextrose and glutathione have been shown to be important factors inmaintaining structural integrity of endothelial cells. Bicarbonate is included because the aqueous humor has a bicarbonate buffer system; dextrose ~d-glucose) providcs a substrate 5 for various metabolic pathways; and glutathione has been shown to aid the metabolic pump mechanism by maintaining proper Na~ adcnosine-tnphosphatase. GBR has bcen shown effe~ve iD maintaining corneal thickncss and endothelial ccll integrity for up to threc hours.
Whilc the effectiveness of a GBR ocular irrigating soludon has been known fo~ many years, p~ior to the ly 1980's its use in surgery was quite limited due to stability and 10 sterility problems. It is to be appreciated that sterility of an ~phthalmic i~igadng soludon is absolutely essential. To ins~e steIility, it iS desirablc ~at an irngadng soludon be prepaclcaged so that the quality and sterility may be closcly monitared and testod as contrasted witb an e~ctempa~aneously mixcd solution as might bc prepared in a hospital pharmacy. lhe solutio~ will peIfuse tbc eye in esscndally a closed system where evcn a small numb of organistns, such as pscudomonas aeruginosa, can produce-an overwhelming endoph~almitis. GBR may not be prepa~cd due to the long term incompadbility and/or insa~bility of its various moietdes. Of thc moiedes added to Ringer's soludon to formulate GBR, bicubonae is pe~haps the most impartant. The bicarbona~ as well as tbe phosphate in a bicarbon~te-phospbatc buffer system may f~m insoluble prccipitates with Mg~ and 20 C~. While at the ionic concentrations useful in ophthalmic imgadon, precipitadon is nrot a problem in freshly prcpared soludon, long-term storage is proscribed. As insoluble crystals introduced into the cye will cloud vision, the importance of keeping a tissue ilIigating solution ~e of insoluble pre~pitates may be readily appreciated.
Complicating the maintenance of GBR's stability is the fact that the pH of GBR will 2s gradually increase due tO the inadequacy of the bicarbonate-phosphate buffer. To provide proper pH, i.e., about 7.4, the~pH of the onginal GBR solutions prepared in ~e hospitil pharmacy bad to be monitored and adjusted with CO2 immediately pnor to use and even dunng use. The chances for contamination dunng pH adjustment was great.
;~ A fur~er factor which proscribcs long-tenn storage of GBR is the unavailabiLity of 30 a proper pH at which all of the moiebes are stable. Several moiedes of GBR are unstable at the physiological pH of about 7.4. Below a pH of about 8, bicarbonate generally decompo_ to C~O2, resulting botb in a loss of bicarbonate concen~ation and increased pH.

Wo 94/08602 pcr/vs93/o9912 5 2~ 2~S~c~
On the other hand, glucose stability requires a pH of less than about 6. Glutathione, while biologically effective dther in reduced oq oxidized fonn, is preferred in the oxidized fonn because the reduced form quickly oxidizes in aqueous solutions, preventing proper labeling of the irrigadng soludon. Oxidized glutathione (glutathione disulfide~ is unstable over s extenW periods of time at a pH of above about 5. The concentration of glutathione may also decreasc to an unacceptable concentration when stored over long periods of time in admixture with all other components. Because of the demonstrated e~lcacy of GBR as an ocular irrigating soludon, it was highly desirable to provide a fonnulation which contains the essential factors found in GBR and which could be stored in a sterilized form for use in eye o surgery. The invention dcscribed in U.S. Patent No. 4,550,022 providcd such a product.
An embodiment of the two~ t imgadng solution described in U. S. Patent No.
4,550,0æ known as "BSS Plus~ Intraocular l~riga~ng Soludon" was imIoduced by Alcon l~baunies, Inc. in the early 1980's. Although that product has been remarkably successful in both a scien~fic and commercial sense, the need for inclusion of adjuncdve drugs ha!s become inc~easingiy app~ent. Mcre specifically, it has been noted that ophthalmic su~geons are in many cases adding adjunctive drugs to BSS Plus following mixing of the two parts of the p~duct. While this so~t of practicc is not uncommon (ie., physicians frequently add drugs to in~ravcnous soludons), it does present added risks with respect to possible inappr~iate final dn~g concentrations, and chemical or microbial contamination of the solution, and is genGrally not convenient for the physician or operating room personnel. It is, dlerefore, highly desirablg to include adjunctive drugs direcdy in ~e ~iga~ng solution at the ~me of mam~facn~e, if possible. UnfartuIIaoely, as discussed ab~ve, these solutions tend to be complex in ~ms of chemical incompatibilides, required pH condidons, and so folth. This is also t~ue of many of the adjunctive drugs which ophthaLTnic surgeons may 2s desire to add to the solution. One such drug is epinepbIine.
Epinephline is i~equently used in the field of ophthalmology to ef~ect dilation of d e pupil (i.e., mydIiasis). The use of this drug is particularly prevalent in ophthalmic surgical procedures, since dilation of the pupil is frequendy necessa~y in order to increase surgeons' ability to see inside dle eye with the aid of a microscope. More specifically, dilation of the - 30 pupil during intraocular surgery is necessary to allow visualization and manipulation of tissues which lie behind the plane of the iris, including the lens, re~na, and all ocular , .

WO 94/08602 PCr/USg3~0ss12 '~?.b~ 6 structures in the postenor segment. Pupillary dilation is accomplished by the use of sympathomime~ agents which stimulate the iris dilator muscle.
Intraocular injections of epinephrine are fr~quendy used during ophthalmic surgical procedures to produce and maintain mydriasis during surgery. The epinephrine may be hjcc~d dirocdy h the eye and/or may be administered as an added component of a surgical i~rigating soludon. The epinephrine added to intraocular irrigadng soludons for constant infusion hto the eye durhg tbc surgical procedD commody consists of commcrcial products intended for parenteral administradon. Parente~al preparadons, bowever, may contain undcsirable additives such as sodium bisulfite, an andoxidant, and chlo~obutanol, a prcscrvative. Tbe pH, osmolality, and buffer capacity of parcnteral epincphrine prcparations may also be inappropriate for in~r use. P ior studies bave sbown tbat the intraocular usc of parcnteral cpinep~ine farmuladons can cause coTneal swelling and loss of co~neal a~ial cclls. Sce Eddb aset, et al., "Corneal Edema and the L~traocular Use of Epi~pl~n, American 1~ of ~Ophtbalmolo~v, volume 93, pages 327^333 (1982).
The ~ osmblaliq and buffedng capacity of soludons injectcd into tbe oye are lhe e~e contains a ~dvdy small volume of fluid (ie., aqueous humor), and mucb of this fluid is lost as a rcsult of the innwcular surgery. ~nsog~ntly, thcre is very 1it~e n~rd fluid remaimng in th~e eye to dilute the deleterious effects o a ~neign solution whicb has apH, osmoJaliq ar~/or buffenng capacity which is incompatible with intraocular tissucs.
For these reasons, tbe intmduction of even a very small volumc of a pbysiologically incompatible soludon into tbc eye can have a very se~ious effect on the viability and funcdon of extremely delicate intIaocul~r tissues, such as the corneal endothelium. In contrast, the injec;tion of fluids into dle blood s~n involves the intmducdon of volumes which are quite small in rclation tO ~e volumes of the receiving mediwn (ie, the blood). Moreover, in the casc of int~nuscular injections, the tissues at the site of the injection are not nearly as sensitiv~ to shifts in chemical equilibrium nor as cridcal to naq~nal physiological functions as intraocular tissues. The criteria for formulating and udlizing parenteral preparations are therefore fundamentally different from the criteria for formulating and utilizing intraocular solutions.
Re~nuy a perv bve-free, sulfite-free sterile epinephrine solution was developedfor a rdiovascular use in children and as~madcs and has been purchased by sts for use as an intraocular inigating solution additive. This sterile WO 94/08602 PCI /US93/09g12 7 2:126~93 preparation allows the administration of epinep'nrine intraocularly without the associated toxic effects of preservatives. See Slack, et al., "A Bisulfite-free Intraocular Epinephrine Solution", Am~ican Journal of ODhthalmolo~v, volume l10, pages 77-82 (l990). However, even this sterile, non-preserved epinephrine solution bears risks associated with 5 extemporaneous compounding, such as concentration eIrors and contamination of the solution during preparation.
The administration of an improper concentration of a sympathomimetic agent during intraocular surgical procedures can have serious consequences. The administration of a low concentration (i.e., relative to the desi~d concentration) is generally not a problem, since the o surgeon will recognize that mydriasis is not being maintained and will therefore supplement the initial administration of the sympathomimetic agent. However, the administration of a high concentration is potendally dangerous. Sympathomimetic agents such as epinephrine constnct blood vessels and thereby restrict blood flow. This restricted blood flow may - conceal the need to cauterize a blood vessel during a surgica1 procedure. After the surgery is completed and the vasoconstricdw effect of the sympathomimetic agent has sub~ided, intr~ocul~ blecding will occur. This condition, ~no~vn as hyphemia, will cause the eye to look vely bloodshot, and may r~quire surgical in~ rvention in order -to stop the bleeding.
Epineph~ine is hlown to be chemically unstable because it is very susceptible tooxidadon when in solution. Since intraocular inigating solutions, particularly GBR solutions 20 such as BSS Plus~ Intraocular ~riga~ng Solu~don are already complex in tenns of the numbe~
of components, the chemical incompadbili~ of certain componen~s, and pardcular pH
conditions needed to maintain the stability of some components, the addi~o~ of an another cponent hlown to be ~ela~vely unstable in solutdon presents a significant problem.
In view of the f~egoing problems, there is a need for an improved in~aocular 2s i~rigating product which contains a sympathon~imetic agent to maintain mydriasis dunng intraocular surgical procedures.

Summalv of the Invention:
A p~incipal obpctive of the present invention is the provision of a standardizedophthalmic phannaceutical composition for maintaining mydnasis and inigating intraocular 30 tissues d~g intraocular surgical procedures. As utilized herein, the term "standardized"
denotes a composition which has certain specified characteristics and properties, and which WO 94/08602 PCI`/US93/09g12 ~ ,6~ 8 is substandally ready for use by ophthalmic surgeons at the time of surgery, without requiring any further, concentration calculadons, dilutions, pH adjustments, or other activities generally associated with the preparadon of pharmaceudcal composidons.
- As discussed above, the extemporaneous addidon of parenteral epinephrine 5 preparadons to ophthalmic irriga~ng soludons at the dme of surgery presents several significant risks, such as the Iisk of an improper conccntradon of epinephrine being utilized The present invcndon eliminates these risks by providing an ophthalmic pharmaceudcal composidon containing epinephrine or a similar mydriatic agent which is spccifically fonnulated and adapted for use as an intraocular i~rigant. Specific advantages of the o compositions of the present invendon therefore include: (1) delivery of a specified, controlled dose of a mydriadc agent to the padent, (2) assurance that the composidon is sterile at the dme of use, (3) eliminatdon of chcmical preservadves, such as sulfites, and other ingredients of parenteral preparadons which arc potentially damaging to intraocular tissues, and ~4? d~ of the pH, osmd~ y and buf~ing capacity of the composidon so that ~: 15 it is ideally suited for mllaocular use. These advantages and other features of the-p~esent in~rendon arc discussed in ~eater detail below.
The intraocular imga~ng composidons of the present invendon includes a first part ; ~ contahning a mydriatic agent. The first part is farmula~d as an acidic soludon. This soludon may be lyophilized to form a powder which is tbcn resolubilized prior toadminis1radon to lhe eye. The low pH of the solution improves the stability of t~he epinep~ine. The first part preferably also includes gluta~ione.
The intraocular ilngadng compositions of the present invention also include a second part containing a buffa to provide an ophthalmically acceptable pH when the first and second parts are combined. The first part preferably also includes one or more electrolytes 2s to facilitate the maintenance of normal cellular function dusing intraocular surgical procedures. Combining the first part and the second part provides a physiolo~gically balanced, standardized solu~on for maintaining mydriasis while maintaining the function and integrity of intraocular dssues.

Description of Plefened Embodiments:
~The imgating compositions of the present invention contain one or more agents to - ~ ~ produce and maintain mydriasis during an intraocular surgical procedure. Such agents are :
, :

WO 94/08602 PCr/US93/09912 2126Q9~

referred to herein as "mydriatic agents". The mydriatic agents used in the present invention are catecholamines having sympathomimedc acdvity. As udli~d herein, the term catecholamine denotes compounds which include a catechol group (~dihydroxybenzene) and an amino group on the side chain. The preferred compounds include epinephrine;
s phenylephdne; dipivalyl epinephdne; norepinephrine; isoproterenol; and the pivaloyloxy and phenylacetyloxy ester derivadves of epinephrine and narepinephrine described in U.S. Patents Nos. 3,8a9,714; 3,839,584; and 4,085,27Q Tbe entire contents of those patents are bereby inanp~ed in the prescnt spec~6cation by reference. Epinepbrine and dipavalyl epinephrine ('~PE") are particul~ly prefe~ Tbe l-isomer of epinephrine is appro~cimately 20 times o more acdve than the d-isomer, usc of the l-isomcr is therefore prefe~rcd. The ~igating solutions of the prescnt invendon will typically contain one or morc mydriatic agents in an amount of about QOû05 to 0.11 mM~.
The ilTigating solutions of tbe~ prescnt invention are farmed by combLning t vo or more parts immediately prior to an ophtbalmic surgical procedb~re. Tbe above~escribed s mydnatic agents are con~ined in a first part which is f~mulated as an acidic composition.
These agents, particulaIly epinephrine, are relatively stable in an acidic environment. A pH
of from about 3 to about 5 is prefen~ A pH of about 3 is most p~efe~red far cpinepbrine.
The ~cidity of tbe solutions gready enhances the stability of tbe myddadc agents, pardcularly epi~ephnne.
The acidic composidons containing one or more mydriatic agents prefe~ably also contain glutathione to assist in the maintenance of corneal endothelial cells. As used herein, "glutatbione" encompasses both the r~duced ~i.e., sulfhydryl) and oxidized (ie., disulfide) fo¢ms of tbis compound; however, use of tbe oxidized faQnn of glutathione is prefeIred.
Glutathione is available from various commercial sources.
~s The invention may be embodied in various types of imgating solutions. The most preferred embodiment is a two-part product similar to BSS Plus~ Intraocular ~Tigating Solution (Alcon Laboratories, Inc., Fort Worth, Texas USA). The first part is an acidic soludon containing one or more mydriadc agents, and preferably also glutathione. The second part is a buffercd, neutral solution containing one or more elec~olytes. The composidons of the nvo parts are such that each is individually stable and may be separately st~;d for long pNiods. When the first and second pans are combined, dle resuldng solution - ~ is useful fo¢ ocular surgery as it contains the necessary factors to maintain mydriasis, as well , ~ ~

WO 94/08602 ~;l,6~3Q$~ pcr/us93/og912 as maintain endothelial cell integrity and corneal thickness, during an intraocular surgical procedure. More specifically, when the first and second parts are combined, the resulting irrigating solution contains: one or mo~e mydriatic agents to maintain mydriasis during the procedure; electrolytes necessary fo~ dssue stability, Ca~, Mg~, Na', K~ and Cl-, in a s bicarbonatc-phosphatc buffer, glutathionc; and dextrosc. The elcctrolytes are providcd in proportions conducive to maintaining the physical intcgrity and mctabolism of corneal endothelial cclls and other ocular tissues. For this purpose, the iIrigating solution formcd by combining the above-dcscribed fîrst and second pw wiU typicaUy contain from about SO to about 500 millimoles per liter ("mM/l") Na~, from about 1 to about 10 mM~l K~, from about 0.1 to about 5 mM~ Ca~, ~om about 0.1 to about 10 mM~ Mg~ and from about 50 to about 500 m~ Cl. To maintain thc osmodc stability of the cells, the osmolality is betwccn about 260 and about 330 mOsm and prefcrably about 290 310 mOsm. So as tocloscly match thc physiological pH of 7.4, tbe pH of the final ilTigating soludon is between about 6.8 and about 8.0 and plef~bly about 7.2-7.8. To maintain the fluid pump systcm, u thc bic~ concentration in the combined ilTigadng soludon is bctwecn about 10 and about 50 mM/L To stabilize thc pH, an addidonal buffc~ing agcnt is provided. P~eferably thc buf~ing agent is pbospbate which is provided in sufficient quantity so that fi~al pbosphate concentration of the irrigadng soludon is between about 0.1 and about 5 mM/l.
Thc final inigating solution contains between about 1 and about 25 mM/l glucose and 20 between 0.01 and about 3 mMIl of glutathione.
The neutral, buffered solution provides the phosphate and bicar~onate buffering moieties, preferably in the foq~n of dibasic sodium phosphate and sodium bicarbonate. The pH o~ the solution is adjusted to about the physiological pH, of 7.4, preferably to between about 7.2 and about 7.8. As hereinbefare mentioned, the pH of a bicarbonate-containing 2S solution is preferably above about 8.0 to prevent decomposition of the bicarbonate.
However, the bicarbonate may be stabilized if it is added to a solution with a pH of above about 8 and thereafter adjusted to a pH bet~,veen 7 and 8. Accordingly, when the neutral, buffered solution is prepared, Na2HPO4 is added pIiOl to the addidon of NaHCO3 so that NaH03 is dissolved in a soludon with a pH of between about 8 and 9. The solution is ~o thereaf~ adjusted with dilute acid, such as H2SO4, H3PO4 or HCl, to the desired final pH
- of the neu~al, buffered solution. Alternativdy, carbon dioxide may be added to adjust the P

W094/08602 ~ ~ 2 ~ Q 9 ~ PCI/US93/09912 Potassium and additional sodium are provided in the neutral, buffered solunon in the form of sodium and potassium salts, such as sodium or potassium chlorides, sulfates, acetates, citrates, lactates, and gluconates. The sodium and potassium are compatible with all of the moieties present in the finished tissue irrigating solution, and sodium chloride and s potassium chloride may be added to dther solution or divided between the solutions.
However, in view of the fact that the neutral, buffered solution provides the buffer system, the pH of the final irrigation soludon may be more accuratcly detern~ined if all compatible salts arc included in that solution.
In addition to one or more mydnatic agents, the acidic solution preferably also lO includes Cà~ in the fonn of calcium chloride, Mg~ in the form of magnesium chloride, glutuhione and dextrose. The pH is adjusted to below about S to provide long-term stability to the myddatic agent, glutathione and dextrose. When epinephrine is udlized as the mydriadc agcnt, a pH of 3 is most preferred fa¢ tne acidic soludon, since this pH has been found to be optimal for cnhancing the stability of epinephrine.
IS As indicated above, the composidons of the present invention are standardized More spcifically, the volumes of the neutral, buffered soludo~ and the acid composition are selected so that adding the en~ire acid composition to the entire neutral, buffered solution results in a solution which contains an amount of one or mo~ mydriatic agents effecdvc to maintain mydriasis during an intraocular surgical proccdure, and has a pH, osmolality and 20 buffering capacity adapted for inigation of inlraocular tissue. This eliminates the need 1 calculate concentradons, measure volumes and/or perform dilutions, all of which create risks of concentration eITors ~d microbial contaminatio~. Because of dle reql~iIement that the acidic soludon have a low pH, it is preferable ~at the volume of dle neu¢al, buffe~ed solu~on gready exceed dle volume of the acidic solution and that the acidic solution contain 2s no buffering agents. The acidic solution may be adjusted below a pH of about S widl a relatively small amount of HCl. Because dle acidic solution is unbuffered, its pH is a reflection of the acid concentration and less acid is needed to adjust ~e pH of a small volume. The large volume of neutral, buffered solution may be adjus~ed very close to the final pH of the i~rigating solution and will be rela~vely unaffected by the addinon of the 30 small volumc of the acidic solution. Prcferably, the ratio of the volume of the neutral, buffered solution volume to the acidic solution volume is about 10 to 1 to about 50 to 1.
A ratio of 25 to 1 is particularly prcferred.

wog4/08602 ~9~ 12 Pcr/US93/09g12 If the acidic composition is provided in the folm of a solunon, rather than a lyophilized powder, the use of a relatively concentrat~, small volume solution is preferred.
The use of a more concentrated soludon is believed to enhance the stability of mydriatic agents such as epinephrine when those agents are in solution. In the absence of an s antioxidant, epinephrine breaks down through two primary mechanisms: racemization and oxidation. Racemization leads to d~pinephrine which is twenty times less active than l-epinephrine. There is less driving force for these decomposition reactions when the same quanaty of epineph~ine is dissolved in a smaller volume of solution. In other words, mare concentrated epinephrine solutions are less prone to decomposition due to the kinetics of low ! volume soludons, reladve to higher volume solutions. The stability of the epincphrine solutions is also enhanced by bubbling nitrogen through the solution to remove oxygon.
However, it may not be possible to rcmove all of the oxygen by means of this technique.
Utilizing a smaller volume solution results in less water and therefo~e less oxygen being present. Thus, the use of a smaller volume solution inherently reduces th~ amount of oxy~en 15 prcsent. The use of volumes on ~e ordcr of lO to 20 milliliters or less for the acid selution are preferred The neutral, buffered solution and the acidic composition are sterilized and separately bottled or contained u~der sterile conditions by standa~d ~hniques, such as autoclaving, or use of sterili~ng filters, but preferably by heat sterilization. Typically, ~e 20 neutral, buf~xed solution, which ~imarily contains inorganic moieties, is autoclave~, whereas ~he acidic solution, which preferably contains the orga~ic components, is microfilt~
The above-descIibed, two-part compositions may be packaged in various types of pharmaceutical containers. Por example, ~e cornposi~ons may be packaged in a con~uner 2S having a first chamber f~r the neutral, buffered solu~on, an isolated second chamber for the acidic solu~on, and means to communicate the chambers without opening the container.
The use of containers fonned fr~m Type I or Type-I SO2-~eated glass are preferred.
The two-part compositions of the present inven~on may also be packaged by means of a combination of a bottle for the neutral, buffered solution and a syringe for the acidic 30 composition containing one or more mydriatic agents. The acidic composition may be contained in the syringe as either a sterile solution or a sterile, lyophilized power. If it is in the fonn of a Iyophilized powder, the powder may be reconstituted by drawing an amount 2~26~3 of the neutral, buffered solution sufficient to dissolve all of the powder into the syringe. A
s~rile diluent otner than the neutral, buffered solution can also be utilized to dissolve the Iyophilized powder. A two-compartment synnge can also be utilized, with the lyophili~ed powder in one compar~nent and a diluent for the powder ~n a second compartment. The s compar~ents are separated by a movable stopper or membrane which can be displaced by depressing the plunger of ~e synnge, thereby allowing the diluent to be combined with the powder. Once the powder is dissolved, the resulting solution is then added to a bottle containing the neu~al, buffered solution by inserling a cannula attached to the front of the sylinge through a stopper in the t~p of the botde.
o Ihe first and sccond parts can also be packaged in separate bottles. A sterile double-ended needle can be used to transfcr the acidic solution to the neutral, buffe~ed solu~on by aseptic~lly inser;ting one end of thc needle into a vial containing the acidic solution and then aseptically inser~ng the other end of tne needle into the neutral, buffered solution package, whereby the vacuum that is maintained therein lransfers tbe acidic solution to the neutral, IS buffcred solution and is mixed.
The two-part composidon of the present invention also provides an advantage as to safety if a technician should fail to properly mix tbe two solutions~ The pH and osmolality of tbe larger volume neutral, buffered solution are at or near pbysiological levels, so that ~e~e is ~ess cbance of toxicity if ~e neutral, buffered solution were used witbout tbe acidic composidon being mixed tberewitb.
The pl~SeM invention may be embodied in va~ious t~s of formulations.
Representative formulations are descnbed in the following examples.

The following two-part formuladon is similar to the BSS Plus~ brand intraocular 2s irriga~ng solution available from Alcon Laboratones, ~c., Fort Worth, Texas, USA. ~at product, which is described in United States Patent No. 4,550,022 (Garabedian, et al.), consists of two solutions refened to as "Part I" and "Part II", respecdvely. ~e following description illustrates how that product or similar products could be modifled ~ incorporate the present inven~on.

WO 94/08602 ~ 93 PCr/US93/09s12 Part I ( neutral, buffered solution) is made by dissolving sodium chloride~ potassium chloride, and anhydrous dibasic sodium phosphate in water for injection at about 20 C.
Then sodium bicarbonate is added and dissolved. Additional water for injection is added to make the desired volume and lN HCl is added to adjust the pH to about 7.4. The solution s is then passed through a 0.45 micron Millipore filter and placed in a bottle. I~e filled bottle is then stoppered, vacuumed and sealed. The sealed bottle is sterilized by autoclaving at 121' C for about 23 minutes.
Part II (acidic soludon) is made by dissolving calcium chloride dihyd~ate, magnesium chloride hexahydrate, dextrose, reduced glutathione and epinephrine in water for injecdon.
o The soludon is then sterile filte~ed tbrough a 0.22 micron membrane filter and asepdcally f~ed into a pres~ilized botde and sealed with a presterilized rubber stopper.
When P~rts I and II are combined, the composidon of the resul~ing fonnula~on is as follows: -In~redients Concentration ~mWI) ~.
IS Glutathione 0.01-3.0 1- EpinephIine 0.0005-0.11 Bicarbonate 1-50 Calcium 0.1-5 Magnesium 0.1-10 ~o Potassium 1-10 Sodium . 5~500 Phosphate 0.1-5 Glucose 1-25 Chlonde 5~500 Sodium Hydroxide AdjustpH
and/or Hydrochloric Acid Adjust pH
Wate~ far Injec~on QS

As explained in ~eater detail in the following example, it is important to protect the 30 Part Il solu~on from light in order to prevent photo decomposition of the epinephrine.

WO 94/08602 PCrJUS93/09912 ;~ ~1 2 ~ ' .Q ~j The following formula~on is a more specific example of the Part ~ solution described in Example l above:
In~redients Percent (wei~ht/volume) s OxidizedGluta~ione, USP 0.46 + 25% xs 1- ~3pinephrine, USP 0.0025 ~ 10% xs Calcium Chlo~ide (Dihy~ate) USP 0.385 Magnesium Chloride Q500 (Hexahydrate) USP
o ~ex~ose Anhydrous, USP 2.3 Sodillm Hydr~xide, NF QS to pH 2.0 to 6.0 andlor Hydrochlo~ic Acid, NF
Wate~ fo¢ injection, USP QS to 100 ~s This fo~mulation may be pr~pared by means of the following procedure. First, all glassware is washed wi~ hot water for injection ~"WFI") depyrogenated at 250 b~ore use.
TJIen each of the following ingredients is sequen~blly added to about 80% of the total volume of WFI to be u~lized, allowing each ingredient to dissolve befare ~e next is added:
Calciwn Chlo¢ide, DihydIate, USP
Magnesium Chlonde, Hexahydrate, USP n ~ex~os~, USP
~luta~hione, USP
EpineR~ine, USP

It should be noted dlat it is impo~tant to protect the solu~on fr~m light, heat, metal sur~aces 2s and oxygen after the additior: of epinepl~e. The pH of the soludon is then checked and, if necessa~y, adjusted with hyd~ochloric acid NF and/or sodium hydroxide, NF. WFI is dlen added in an amount sufficient to reach 100% of the intended batch volume~ and the resul~ing solution is ~ed by sti~ing. The soludon is dlen passed through a 0.2 micron membrane filter into a pyrogen-~ee container. The container is ~en flushed with nitrogen gas (a 30 nitrogen blanket is maintained over the solution to displace air and protect the solution ~om oxidation). ~nmediately af~er flushing ~e filled container with nitrogen gas, it is sealed by Wo 94/08602 PCI/US93/09912 means of a rubber stopper. The filled and sealed container is ~en placed in a cardboard box or sealed pouch to protect the contents, particularly epinephrine, from light during storage.

lhe following f~mulation represents another embodiment of ~e present inventio~, s wherein phenylephrine is u~lized as the mydriatic agent in the acidic solution instead of epinephrine.
~redients Percent (wei~ht/volume) Calcium Chloride, dihydrate 0.385 Magnesiurn Chloqide, hexahydrate 0.5 o Dex~ose, anhyd~ous 2.3 Glutathione Disulfidle 0.46 + 10% xs Phenylephrine Hydrochl~de 0.005 Sodium Hydroxide, NF AdjustpH
Hydrochl~c Acid, NF Adjust pH
s Wate~forI~jecdon QS 100 This formul~tion can be prepared ~ acco~dance with ~e pr~cedures deseribed in Example 2 above.
The ~vention may also be embodiçd i~ products f~nnulated or corlfi~ di~er~ndy ~om d~e tw~part p~duct described above. Fo~ example, ~e acidic solution containing Buta~ione and epinephrine or anothar sympathomime~c compound can be lyophilized (i.e., ~eeze-dried) following p~epa~ation and then reconstituted as a soludon pri~r t~ use. Ihe low pH of the ~id svlution will have a stabilizing ef Fect on epinephrine, both when the solu~ion is initially fonned, and after the lyophilized soluhon is recons~ut~i The solution may be lyophilized in one basic step, o~ s~parate solutions may fîrst be sequendally frozen in a single container, and dlell iyophilized, as described in United States Patent No. 4,97~,419.
The lyophiliwd powder must be sto~ed in a sealed container, and that container should be pla~ed in a sealed pouch consuucted of a moisture impervious material, such as foil. The pouch should be opa~ue, in order to protect the epinephrine from light, and preferably also contains nitrogen gas, in order to protect the epinephrine from oxygen. If a bul~ng agent, W0~4/08602 2 1 2 6 0 ~ 3 Pcr/usg3/o99l2 such as mannitol, is utilized to form the lyophilized powder, this may increase the osmolality of the solution, and therefore necessitate an adjustment in the amount of sodium chloride contained in the second part of the composition.
In view of the instability of epinephrine, special precautions may need to be taken 5 during the manufacturing of the compositions of the present invention, particularly the first part wbich comprises epinephrinc or another mydriatic agent. If epinephrine is utiL~ized as the mydnatic agent. it will need to be protected fmm light, heat, oxygen and metal surfaces during thc manufacturing pro ess. In view of the sensitivity of epinephrine to light, only covered tanks or vessels should be used, and lighting of the area around the tanks or vessels lO should be reduced to the lowest e~ctent possible. Ultraviolet light should be totally elimin~, if possible. The epi~ephnne should also be protected from oxygen dunng the manuf=g process. This protection may include the following steps:

(1) using purified water, collected hot then cooled to 25-35C with a nit~ogen sparge, whcn c~npo~ (or a closed, recirculating system w~N2 bead);
(2) maintaining an N2 pu~e of 3I~min fmm the bottom of the compounding (3) filtenng all N2 tbrough a Q22 um or smaller steriLizing filter;
(43 prior to ~Ihng into final coqltainers:
utili~ng a p~ion of the solution to flush a glass-recei~nng ~ac~or (carboy) and tne filling apparatus, and after filling thc glass carboy, flusbing a por~on of the soludon through fill needles to purge air from the lines;
(~) filling into-final containers shardy after compounding; and (6) providing continuous nitrogen flush to filled units prior to capping.

, 2s Other precaudons which may need to be taken will be apparent to those skilled in the art.

, ~ .

Claims (10)

What is Claimed is:

1. A sterile, preservative-free ophthalmic pharmaceutical composition for maintaining mydriasis and irrigating intraocular tissues during intraocular surgical procedures, said composition comprising a first part and a second part, said first part comprising an acidic composition containing a mydriatic agent in an amount sufficient to maintain mydriasis, and said second part comprising a solution which comprises a buffer to provide an ophthalmically acceptable pH when said first part and said second part are combined .

2. A pharmaceutical composition according to Claim 1, wherein the pH of the first part is 3 to 5, and the pH of a solution resulting from the mixing of said first part and said second part is 6.8 to 8Ø

3. A pharmaceutical composition according to Claim 2, wherein the mydriatic agent is a catecholamine.

4. A pharmaceutical composition according to Claim 3, wherein the catecholamine is selected from the group consisting of epinephrine, dipivalyl epinephrine, norepinephrine, phenylephrine and isoproterenol.

5. A pharmaceutical composition according to Claim 4, wherein the catecholamine comprises epinephrine.

6. A pharmaceutical composition according to Claim 2, wherein the composition comprises one or more electrolytes in an amount sufficient to facilitate the maintenance of normal cellular function during an intraocular surgical procedure.

7. A pharmaceutical composition according to Claim 6, wherein the first part further comprises glutathione in an amount sufficient to facilitate the maintenance of normal cellular function during an intraocular surgical procedure.

8. A pharmaceutical composition a cording to Claim 7, wherein the glutathione consists essentially of oxidized glutathione.

9. A pharmaceutical composition according to Claim 8, wherein the concentration of the mydriatic agent in a solution formed by mixing the first part and the second part is 0.0005 to 0.11 mM/l.

10. A pharmaceutical composition according to Claim 9, wherein following mixingof the first part and the second part the composition comprises 0.1 to 5 mM/l calcium, 0.1 to 10 mM/l magnesium, 50 to 500 mM/l sodium, 1 to 10 mM/l potassium, 50 to 500 mM/l chloride, 0.1 to 5 mM/l phosphate, 1 to 50 mM/l bicarbonate, 1 to 25 mM/l dextrose and 0.01 to 3 mM/l oxidized glutathione.