SILVER-BASED ANTIMICROBIAL COMPOSITIONS

FIELD OF THE INVENTION

The present invention relates to silver-based antimicrobial compositions and processes for making such compositions that are suitable for use in the treatment and prevention of infections

BACKGROUND OF THE INVENTION I. Antimicrobial Agents Antimicrobial agents are chemical compounds that either destrov microbes, prevent their pathogenic action, or prevent their growth Antimicrobial agents, often referred to as anti-infective agents, are frequently applied topicallv to the skin and mucous membranes in the form of a solution, cream, or ointment, appropriate formulations mav be applied to wounds and body cavities, and to the eyes, nose, and mouth In general, topical antimicrobial agents are directed at bacteria, viruses, and fungi

They have been used successfully in the prevention and treatment of a number of infections. including impetigo, candidiasis. tinea pedis (athlete s foot), acne vulgaπs, and infections resulting from burns and surgical wounds

Most agents have a limited spectrum of activity For example, some are specific for particular gram (+) organisms, while others are specific for particular gram (-) organisms

Moreover, bactericidal agents tvpicallv are not fungicidal w hile fungicidal agents tvpicallv are not bactericidal

In addition, due to the widespread use and frequent over-prescribing of antimicrobial agents, there is an increasing incidence of microbes acquiring drug-resistance In other words, Λ microbe that was once susceptible (i.e , inhibited or killed) to a particular antimicrobial agent is no longer susceptible This is especially important with regard to bacteria

Acquired drug resistance is usually caused bv a mutation within the genome of the microbe or bv the acquisition of a plasmid For example, one of the ma|or mechanisms of resistance to the β-lactam antibiotics, including penicillins is the production of β-lactamases Moreover, resistance to one member of a class of agents (e g , the aminopenicilhn ampicilhn) can result in complete cross-resistance to other members of that class { e.g., the aminopenicillin amoxicillin)

II. Topical Silver-Containing Agents

A. Currently Used Therapeutic Agents

Two formulations containing silver have been utilized for therapeutic purposes, silver nitrate and silver sulfadiazine As set forth hereafter, each is associated with potentially severe adverse effects and other limitations

A 1 % silver nitrate ophthalmic solution can be used in newborns for the prophylaxis of gonococcal ophthalmia (gonococcal ophthalmia neonatorum) Because the silver ion is precipitated by chloride, the silver nitrate solution does not readily penetrate into tissue. Unfortunately, the silver salts stain tissue black as a result of the deposition of reduced silver, some of the staining may persist indefinitely Thus, silver nitrate is not used topically for other indications (e.g. , impetigo)

Silver sulfadiazine 1 % topical cream is routineiv used as an adiunct in the prevention and treatment of infection in burn victims [See U S Patent No 3,761.590 to Fox. hereby incorporated by reference] Silver sulfadiazine. produced by the reaction of silver nitrate with sulfadiazine, has been associated with necrosis of the skin In addition, sulfadiazine may accumulate in patients with impaired hepatic or renal function, requiring in severe cases examination of the patient ^' s urine for sulfonamide crystals Moreover, patients allergic to sulfa agents may exhibit cross-hypersensitivity with silver sulfadiazine [See generally, AHFS Drug Information. Gerald K McKevoy, ed , pp 1704-05 and 2215- 16 ( 1993)] B. Newer Antimicrobial Silver-Containing Compositions

One of the reasons whv there are few commerciallv available silver-containing therapeutic formulations is the difficulty of making such formulations photostable That is, such formulations turn a dark color and frequently lose antimicrobial efficacy upon short-term (e.g. , 3-4 days) exposure to ambient light There have been several recent efforts to produce a silver-containing formulation that exhibits high antimicrobial efficacy and photostability For example, U S Patent No 5,326,567 to Capelli, hereby incorporated bv reference, describes an antimicrobial composition comprising a stabilizing acyclic polyether polymer, silver ion. and a stabilizing halide The composition may be used in several manners, including topical application to a subiect and incorporation into a medical device

In addition, a new class of silver-containing agents, the silver thiosulfate ion complexes, has recently been disclosed in U S Patent No 5,429,819 to Oka et al. (hereafter "the Oka Patent"), hereby incorporated by reference [See also Tomioka el al.. "Synthesis of

Antimicrobial Agent Composed of Silver-Thiosulfate Complex Ion." Nippon Kagaku Kaishi 10 848-50 ( 1995)] The Oka Patent describes an antiviral composition that contains I) a thiosulfate salt and n) at least one thiosulfate complex salt of a metal and πi) a porous particulate carrier, the metal is either silver, copper or zinc, and the salts are carried on the porous paniculate carrier According to the Oka Patent s teachings, the thiosulfate complex salt and thiosulfate metal complex salt are first prepared as a solution Thereafter, a porous carrier such as silica gel is impregnated with the solution Finally, the thiosulfate complex and thiosulfate metal complex salt are immobilized on the porous carrier through drying This metal-containing porous carrier is then formulated into the compositions described in the Oka Patent

The antimicrobial compositions taught in the Oka Patent are associated with several notable shortcomings First, the silver thiosulfate ion complex compositions contain a l elativelv large concentration of waste salts, resulting from the complexation of a thiosulfate salt, sulfite salt, and a silver salt, and are thus relativelv impure For example, producing 1 part of a silver thiosulfate ion complex using 1 part of silver nitrate (or silver acetate) to 2 parts sodium thiosulfate and/or 2 parts sodium sulfite will result in 1 part waste sodium nitrate (or sodium acetate), the inclusion of these salts results in a lower concentration of silver Similarly, as indicated above, the silver thiosulfate ion complex requires the use of porous carrier particles, the necessity of these carrier particles limits the concentration of thiosulfate complex salt and thiosulfate metal complex salt Thus, the amount of porous carrier particles needed to provide silver at antimicrobial concentrations is high, and. as a result, a topical antimicrobial composition would feel gπttv and would be irritating to the skin oi wound In addition, if the concentration of thiosulfate complex salt and thiosulfate metal complex salt carried on the porous carrier is too high, the composition av discolor Finally, the compositions taught by the Oka Patent cannot be easily incorporated into a polymer matrix at high concentrations As stated above, incorporation of silver at antimicrobial concentrations requires concomitant incorporation of a large amount of porous carrier This can cause undesirable changes in the polymer matrix' physical properties (e.g. , a hvdrocolloid matrix that is stiff and less absorptive) In addition, such incorporation can be unwieldv For example, in an alginate matrix containing water-insoluble fibers, the silver- containing porous carrier cannot be incorporated into the alginate fibers, as a result, the porous carrier must be mixed loosely within the alginate fibers Unfortunately, the porous carrier can fall out when the almnate matrix is handled

From the above, it should be clear that the commerciallv-available silver-based antimicrobial agents have limited applications and can be associated with severe adverse effects Moreover, many recent efforts to develop a topical silver-containing formulation are connected with drawbacks, as exemplified bv the prior art requirement of a carrier What is needed is a stable silver-containing antimicrobial composition which is suitable for use in the treatment and prevention of a broad range of infections and that is not associated with the adverse effects and limitations of the agents that have previously been described

SUMMARY OF THE INVENTION The present invention relates generally to silver-based antimicrobial compositions and processes for making such compositions suitable for use in the treatment and prevention of infections In particular, the present invention relates to stable silver-based antimicrobial compositions, and processes for making such compositions, comprising carrier-free, suspended silver thiosulfate ion complexes in a base Preferably, the silver thiosulfate ion complexes are homogeneously suspended in an anhydrous base Alternatively, the silver thiosulfate ion complexes of the present invention can be incorporated into a matrix and used with a medical device Pharmaceutical compositions can also be produced bv combining the silver thiosulfate ion complexes with medicinal agents, including but not limited to antimicrobial agents, steroids, and anesthetics One advantage of providing silver thiosulfate ion complexes in a carrier-free form is the abilitv to produce antimicrobial compositions containing high concentrations of silver thiosulfate ion complexes so as to provide potent antimicrobial activity \ further advantage of the carrier-free compositions is the elimination of irritation that mav result from the carrier upon topical administration Thus, the invention contemplates a method of treating or preventing infections in comprising applying topically to the site (or potential site) of infection an effective amount of the foregoing composition

Λs alluded to above, the invention also contemplates methods of making the stable silver-based antimicrobial compositions It is preferred that the silver complexes of the present invention are derived from the complexation of silver cations from silver ha des (preferably silver chloride) with anions from the sodium thiosulfate salts, the molar ratio of the thiosulfate anions to the silver cations is preferably at least I 1 and more preferably at least 1 3 1 It is desirable that the silver thiosulfate ion complexes are solid and essentially

pure. / e . thev do not contain significant amounts of waste salts or other substances that interfere with their antimicrobial activity, in addition, they do not require carrier particles

The compositions are able to contain high concentrations of silver thiosulfate ion complexes, thereby providing strong antimicrobial activity Moreover, the compositions may be used in combination with other pharmaceutical (e g , topical) agents ( g , Bactroban ^κ

[mupirocin], SmithKline Beecham) Such combination mav serve to avoid antimicrobial resistance, increase the spectrum of activity, and have a svnergistic effect

The silver thiosulfate ion complexes of the present invention may be incorporated into medical devices, including medical implants, wound care devices, body cavity and personal protection devices, and the like By way of illustration, purified silver thiosulfate ion complexes may be incorporated with an anhydrous polymer matrix that is used to coat a uπnarv catheter in order to prevent infection Similarly, the silver thiosulfate ion complexes mav be used in cosmetics and personal care products to make them resistant to antimicrobial contamination Examples of cosmetics include lipsticks and glosses, l ip pencils, mascaras, eve l iners, eve shadows, moisturizers, liquid and powder makeup foundations, powder and cream blushes, perfumes, colognes, v arious creams and toners, etc . and assorted applicators like combs, brushes, sponges, and cotton swabs and balls, and examples of personal care products include deodorants, razors, shaving creams, shampoos, conditioners, v arious hair treatments like mousses and spravs, toothpastes, mouthwashes. dental flosses and tapes, sunscreens, moisturizers tampons, sanitary napkins pantv shields, diapers, baby wipes, facial tissues, toi let tissues, etc

The present invention contemplates a composition comprising carrier-tree suspended si lver thiosulfate ion complexes suspended in a base In one embodiment, the base is anhydrous It is contemplated that the concentration of si lver thiosulfate ion complexes within the base is sufficient to provide a therapeutic benefit Specifically, the present invention contemplates concentrations of si lver thiosulfate ion complexes within the base from 0 0 1 % to 30% (w/w ) and from 0 1 % to 3 0% (w/w) The preferred concentration of silver thiosulfate ion complexes within the base is from 0 2% to 1 5% (w/w) In one embodiment, the base is selected from the group consisting of polyethvlene glycol Λquaphor' and white petrolatum The present invention also contemplates a method of treating or preventing a topical microbial infection, comprising the steps of a) providing I ) a subiect infected with a topical microbial infection and n) an effective amount of carrier-free suspended si lver thiosulfate ion complexes in a base, and b) administering topically the effective amount of the carrier-free

suspended silver thiosulfate ion complexes in a base to the subiect thereby treating or preventing the topical microbial infection In one embodiment, the base is anhydrous

It is contemplated that the concentration of silver thiosulfate ion complexes within the base is sufficient to provide a therapeutic benefit For example, the present invention ^ specifically contemplates concentrations of silver thiosulfate ion complexes within the base trom 0 01 % to 30% (w/w) and from 0 1 % to 3 0% (w/ ) The preferred concentration of silver thiosulfate ion complexes within the base is from 0 2% to 1 5% (w/w) In one embodiment, the base is selected from the group consisting ot polvethvlene glycol, Aquaphor ^κ , and white petrolatum

10 The present invention further contemplates a method of imparting antimicrobial protection to an ob|ect comprising the steps of a) providing l) an ob|ect and n) an effective amount of carrier-tree suspended silver thiosulfate ion complexes and b) applying the ettectiv e amount of the carrier-free suspended silver thiosultate ion complexes in a base to the obiect, therebv imparting antimicrobial protection to the obiect It is preferred that the object

1 is solid and chemically inert

In one embodiment the concentration of silver thiosultate ion complexes is sufficient to provide a therapeutic benefit Specifically the present invention contemplates concentrations of silver thiosulfate ion complexes trom 0 01 % to 30% (w/w) and from 0 1 % to 3 0% (w/w) The preferred concentration of silver thiosultate ion complexes is from 0 2%

20 to 1 5% (w/w)

In still further embodiments the obiect is a medical device In particular embodiments the medical device compnses a matrix In some embodiments the matrix is a polvmer while it is anhydrous in still further embodiments

The present invention also contemplates a process tor producing essentially anhydrous

^" • silver thiosulfate ion complexes comprising a) making an aqueous solution of silver thiosulfate ion complexes, b) adding a solvent to the solution to create a biphasic separation wherein the silver thiosultate ion complexes separate into one phase c ) collecting the phase containing the silver thiosulfate ion complexes and d) removing water from the collected phase such that the silver thiosulfate ion complexes are essentially anhvdrous In particular embodiments the ratio of thiosulfate ions to silver ions is greater than or equal to 2 1 and preferably less than 3 1

In some embodiments the aqueous solution ot si l er thiosulfate ion complexes is formed bv reacting a silver hahde and sodium thiosulfate In other embodiments, the molar

ratio of silver cations from the silver ha de to thiosulfate anions from the sodium thiosulfate is preferably at least 1 1 and more preferably at least 1 3 1 In still further embodiments, the silver hahde is silver chloride

In other embodiments, the solvent is water-miscible The solvent is selected from the group consisting of ethyl alcohol, isopropyl alcohol, methvl alcohol, acetone, and tetrahvdrofuran in certain embodiments

Additionally the present invention contemplates a process for producing essentially anhydrous silver thiosulfate ion complexes, comprising a) making an aqueous solution of silver thiosulfate ion complexes, b) adding a solvent to the solution to precipitate the silver thiosulfate ion complexes, c) collecting the precipitated silver thiosulfate ion complexes, and d) removing water from the collected silver thiosulfate ion complexes such that the silver thiosulfate ion complexes are essentially anhydrous In particular embodiments the ratio of thiosulfate ions to silver ions is less than 2 1 and preferably greater than I I

In some embodiments, the aqueous solution of silver thiosulfate ion complexes is formed by reacting a silver hahde and sodium thiosulfate In other embodiments, the molar ratio of silver cations from the silver hahde to thiosulfate anions from the sodium thiosulfate is preferably at least I 1 and more preferably at least 1 3 1 In still further embodiments, the silver hahde is silver chloride

In other embodiments, the solvent is water-miscible The solvent is selected from the group consisting of ethvl alcohol, isopropyl alcohol, methvl alcohol, acetone, and tetrahvdrofuran in certain embodiments

The present invention also contemplates a pharmaceutical mixture, comprising a) a medicinal agent, and b) silver thiosulfate ion complexes In preferred embodiments, the silver thiosulfate ion complexes are carrier-free In particular embodiments, the pharmaceutical mixture further comprises an anhydrous base, in some embodiments, the base is selected from the group consisting of polyethylene glycol. Aquaphor ^* . and white petrolatum

In some embodiments of the present invention, the concentration of the si lver thiosulfate ion complexes in the pharmaceutical mixture is from 0 01 % to 30% (weight to weight) In further embodiments, the concentration of silver thiosulfate ion complexes is from 0 1 % to 3 0% (weight to weight), while in still further embodiments the concentration is from 0 2% to I 5% (weight to weight)

In particular embodiments, the medicinal agent of the pharmaceutical mixture is an antimicrobial agent In some embodiments, the antimicrobial agent is selected from the group

consisting of acyclovir, chloramphenicol, chlorhexidine chlortetracvchne. ltraconazole, mafenide. metronidazole. mupirocin, nitrofurazone, oxvtetracvchne, penicillin, and tetracvchne When the medicinal agent is an antimicrobial agent, in some embodiments the pharmaceutical mixture has a broader spectrum of antimicrobial protection than the silver thiosulfate ion complexes

Furthermore, the medicinal agent of the pharmaceutical mixture is a steroid in certain embodiments In particular embodiments, the steroid is selected from the group consisting of betamethasone benzoate, betamethasone valerate, desonide. fluocinolone acetonide, halcinonide, hydrocortisone. and metandienone Finally, the medicinal agent of the pharmaceutical mixture is an anesthetic in still other embodiments In certain embodiments, the anesthetic is selected from the group consisting of benzocaine. dibucaine docaine pramoxine hvdrochloπde and tetracacine

DEFINITIONS To facilitate understanding of the invention set forth in the disclosure that follows, a number of terms are defined below

The term "carrier" refers to a substance, like an inorganic oxide, in which a material can be impregnated and then, if necessarv, immobilized through drying For example, the Oka Patent describes the impregnation of a porous particulate carrier (e ., silica gel) with a solution containing thiosulfate complex salt and thiosulfate metal complex salt In contrast, the term "carrier" does not refer to the mere suspension ot materials like silver thiosulfate ion complexes in a base The term "carrier-tree" refers to being without such things as carrier particles porous paniculate carriers, and the like used as carπeis for other materials For example, the compositions of the present invention are "carrier-free" in that thev comprise silver thiosulfate ion complexes that do not require such a carrier

The term "base" l efers to anv substance useful for the suspension of the silver thiosulfate ion complexes of the present invention In a preferred embodiment, the base is "anhydrous" ( ., an ointment) and can be used to suspend a medicinal agent for topical administration Useful anhydrous bases include, but are not limited to. white petrolatum. Λquaphor" ointment base, and polyethylene glycol (PEG) polymers with molecular weights greater than 600 The preferred anhydrous base is a PEG ointment composition, an ointment made up of PEGs can absorb and associate with a small amount of water so that the water is not free to hydrolvze the thiosulfate hgand It should be noted that some water is tolerable in

the final product but that, generally speaking, the presence of water will reduce the shelf-life of the composition For example, an anhydrous base which contains no water and few, if anv, hydroxv or acid groups should have a shelf-life of many years, while a base containing small amounts of water (e g , less than 5%) would have a shorter shelf-life (e.g , less than 6 months) If a PEG ointment base has a verv small amount of water (e.g., much less than

1 %), the silver thiosulfate ion complexes should be stable enough to provide the product with an acceptable shelf-life ( , greater than one vear) In one embodiment the base is semisohd

The term "silver thiosulfate ion complexes" refers to the silver-containing material produced by the process of the present invention and incorporated into the compositions of the present invention More specifically, the silver thiosulfate ion complexes are obtained by adding a silver hahde, g , silver chloride, to an aqueous solution and then adding a thiosulfate salt, e g , sodium thiosulfate. to the solution Though the benefit provided bv the complexes of the present invention is not limited by an understanding of the precise nature of the complexes, the chemical formula of the primary silver thiosulfate ion complexes formed when a large excess of thiosulfate salt is used is represented by [Ag(S _: 0,), ^" By comparison, the chemical formula of the pπmarv silver thiosulfate ion complexes formed when onlv a small excess of thiosulfate salt is used is represented bv [Ag,(S _: 0 ₁ ) ₁ ] ^{4 "} The preferred silver thiosulfate ion complexes are those represented by [Ag _: (S _: 0 ₁ )ι] ^4' The resulting silver thiosulfate ion complexes are in a relatively pure solid form, and are stable, highly water soluble and antimicrobial! v activ e

The term "essentially anhvdrous silv er thiosulfate ion complexes" l efers to silver thiosulfate ion complexes that mav be essentially free of all remnant water. / e they mav contain a small amount of water (generally less than 5% of the original amount of water present preferably less than 1 % and most preferably less than 0 1 %), provided that the water does not interfere with the antimicrobial function of the complexes

The term "suspended" refers broadlv to the dispersion (/ e . not dissolution) of material (e g . silver thiosulfate ion complexes) in the base The material is preferably finely divided and preferably dispersed homogeneously throughout the base The term "aqueous solution" refers to a liquid mixture containing, among other things, water

The term "solvent" refers to a liquid that is capable of dissolving a substance The term "water-miscible solvent" refers to a solvent that is capable of being mixed with water and remaining so after completion of the mixing process

The term "phase" refers to a physicallv distinct and separable portion of a ^ heterogeneous svstem The term "biphasic separation" refers to the creation of two phases, generally speaking, a "biphasic separation" allows a material (e iζ , silver thiosulfate ion complexes) to be partitioned into one of the resulting phases, therebv facilitating isolation of that material As described in further detail below, the addition of an appropriate solvent (e g , ethyl alcohol) to an aqueous solution of silver thiosulfate ion complexes results in a 0 biphasic separation A smaller, denser, liquid phase primarily contains the silver thiosulfate ion complexes associated with water, there is little, if any, solvent in this phase A larger liquid phase primarily contains the waste salts and the solvent

The terms 'collecting " "collect" and the like refer to the general processes ot isolating partitioning, etc one material from another For example a desired material may partition 5 into one phase of a biphasic svstem. the phase containing that material (e , the silver thiosulfate ion complexes of the present invention) can be removed from the biphasic svstem using well known means (e g , pipet and separatorv funnel )

The term "removing" refers broadly to the use of methods for the complete or partial elimination of water from the phase containing the silver thiosulfate ion complexes (/ e the 0 collected phase) The present invention is not limited to any particular method, rather general ly known methods of removal ( g , freeze drving oven drving evaporation and solvent extraction ) mav be used in coniunction with the present inv ention

The term "effective amount" t efers to that amount of essentially anhydrous silver thiosulfate ion complexes that is required to provide some "therapeutic benefit" The present ^ invention is not limited bv the nature or scope of the therapeutic benefit provided The degree of benefit mav depend on a number of factors, e , the seventy of a S aiireus infection and the immune status ot the individual

The term "therapeutic composition" refers to a composition that includes essentially anhydrous silver thiosulfate ion complexes in a pharmaceutically acceptable form The 0 charactenstics of the form will depend on a number of factors including the site of topical administration and the method bv which the form will be used For example, a composition for use in conjunction with personal care products must be formulated such that the composition retains its antimicrobial properties while not adversely affecting the

characteristics of the personal care product itself The therapeutic composition may contain diluents, adjuvants and excipients. among other things

The terms "subject" and "host" refer to humans and animals

The term "approximately" refers to the actual value being within a range of the indicated value In general, the actual value will be between 5% (plus or minus) of the indicated value

The terms "topical," "topically " and the like include, but are not limited to, the surface of the skin and mucosal tissue, in wounds, in the eves, nose, mouth, anus and vagina

The term "wound" includes a burn, cut sore, blister, rash or any other lesion or area of disturbed skin The term "wound dressing" includes foam dressings, thin film dressings, burn dressings, surgical dressings, absorptive dressings, gauze, sheets or other types of medical device used to treat wounds

The terms "microbe, "m icrobial " and the like include bacteria, fungi, and viruses The terms "antimicrobial" and "antimicrobial activity" refer to the ability to kill or inhibit the growth of microbes

The term "photostable" means that an object or material is resistant to discoloration when exposed to ambient light for a period of at least 72 hours

The terms "matrix, " "matrices" and the l ike refer broadly to materials in which the si lver thiosulfate ion complexes of the present invention can be embedded in. attached to, or otherwise associated with A "polymer matrix" is one tvpe of matrix comprising one or more natural or svnthetic compounds, usually of high molecular w eight, in the form of repeated l inked units The term "anhydrous polvmer matrix " refers to anv sol id material that mav be free ot water or that mav contain a smal l amount of water ( general lv less than 5% bv weight), prov ided that the water does not interfere with the antimicrobial function of the complexes carried bv the matrix The preferred anhydrous polvmer matrix materials are materials compatible with the silver thiosulfate ion complexes of the present invention The most preferred polvmer matrix materials are those being compatible with the silver thiosulfate ion complexes and having some capacity to absorb and/or swel l in the presence of water Examples of anhydrous polymer matrix materials, include but are not l imited to, adhesives such as acryhc-based pressure sensitive adhesives, biopolvmers such as silk, hydrocolloid materials such as sodium carboxvmethvlcel lulose. either alone or when bound in a polymer, and polymers such as polvurethane in the form of coatings, films, foams, etc

The term "medical device" refers broadlv medical implants, wound care devices, body cavity and personal protection devices, and the like Medical implants include, but are not limited to, urinary and intravascular catheters, dialysis shunts, wound drain tubes, skin sutures, vascular grafts and impiantable meshes, intraocular devices, and heart valves Wound care ^ devices include, but are not limited to, general wound dressings, non-adherent dressings, burn dressings, biological graft materials, tape closures and dressings, and surgical drapes Finally, body cavitv and personal protection devices include, but are not limited to, tampons, sponges, surgical and examination gloves, toothbrushes, intrauterine devices, diaphragms, and condoms The silver thiosulfate ion complexes of the present invention can be use to impart

10 antimicrobial protection to objects including, but not limited to medical devices

The term "purified" means that the material has been sub|ected to a process (e g , extraction) to remove impurities Following the process the material mav be free from contamination of extraneous matter or more commoniv only contain impurities at levels that do not interfere with the intended function For example, it is advantageous to produce silver

I thiosulfate ion complexes that do not contain significant amounts of waste salts (e g , sodium nitrate or sodium acetate), if such waste salts are incorporated into compositions or medical devices, thev mav be irritating to the skin or other tissue In addition they mav reduce the concentration of antimicrobiallv active silver For example, if the silver thiosulfate ion complexes are made using silver iodide silver salt and sodium thiosulfate salt, the resulting 0 waste salt would be sodium iodide The iodide ion would aggressively compete for the dissociated ("free" ) silver ion resulting in reduced concentration of antimicrobiallv active si lv ei

DETAI LED DESCRIPTION OF THE INVENTION 5 The present invention relates to silver-based antimicrobial compositions, and processes for making such compositions, that are suitable for use in the treatment and prevention of infections In particular, the present invention relates to stable silver-based antimicrobial compositions, and processes for making such compositions, comprising carrier-free, suspended silver thiosulfate ion complexes in an a base, and silver thiosulfate ion complexes

30 incorporated into an anhydrous polvmer matrix and used with a medical device

The description of the invention is div ided into the following parts I) Processes To Obtain Silver Thiosulfate Ion Complexes In A Solid Form, II) Compositions Containing Silver Thiosulfate Ion Complexes III) Therapeutic Use Of Compositions Containing Silver

Thiosulfate Ion Complexes and IV) Incorporation Of Silver Thiosulfate Ion Complexes Into Matrices For Use In Medical Devices Each of these parts will be discussed in turn

I. PROCESSES TO OBTAIN SILVER THIOSULFATE ION COMPLEXES MATERIAL IN A SOLID FORM

As previously indicated the compositions of the Oka Patent contain a thiosulfate salt at least one thiosulfate salt of a metal, and a porous paniculate carrier The carrier was required because the thiosulfate salt and the thiosulfate salt of a metal can "hardly be obtained as a simple substance in a solid state" [Oka Patent, col 2, 11 45-46] In contrast to the Oka Patent the present invention is directed at a process for obtaining carrier-free silver thiosulfate ion complexes Based on the prior art s acknowledged difficulty in obtaining silver thiosulfate ion complexes in a carrier-tree solid state the discoverv of the process disclosed hereafter w as both surpπsinu and unexpected Moreover the process ot the present invention also results in carrier-free silver thiosulfate ion complexes in high yields, another surprising and unexpected l esult

The present invention contemplates the production ot carrier-free silver thiosulfate ion complexes wherein the ratio of thiosulfate ion to silver ion is preferably at least I 3 to I To optimize the antimicrobial effectiveness of the final products containing the silver thiosulfate ion complexes it is preferable that the complexes be purified (e iζ , subjected to methods to l emove contaminants such as waste salts in an amount that adversely interferes with the silver concentration obtainable)

The present invention prov ides two processes ot producing purified silver thiosultate ion complexes trom thiosulfate ions and silver ions The first process is preferred when the ratio of thiosulfate ions to silver ions is greater than oi equal to 2-to- l and the second process is preferred when the ratio is less than 2-to- l

A. Process For Producing Silver Thiosulfate Ion Complexes

When The Ratio Of Thiosulfate Ions To Silver Ions Is Greater Than Or Equal To 2-to- l The process for producing essentially anhydrous silver thiosulfate ion complexes when the ratio of thiosulfate ions to silv er ions is greater than 2-to- l involves four maior steps The first step consists of making an aqueous solution of silver thiosulfate ion complexes The aqueous solution of the silver thiosulfate ion complexes is obtained bv first adding a silver

hahde such as silver chloride, silver bromide, etc , to an aqueous solution Thereafter, a thiosulfate salt, such as sodium thiosulfate or potassium thiosulfate, is added to the aqueous solution

The use of a silver hahde instead of another silver-containing molecule is preferred because the silver thiosulfate ion complexes produced are associated with increased short-term stabihtv This is especially important when the concentration of the silver thiosulfate ion complexes is high and/or the ratio of thiosulfate ions to si lver ions is low Likewise, the use of a silver hahde promotes stabihtv when making a solution of the si lver thiosulfate ion complexes when the concentration of silver thiosulfate ion complexes in the resulting aqueous solution is high As indicated above when making silver thiosulfate ion complexes where the primary silver ion complexes formed is represented by the formula [Ag(S ₂ 0 ₁ ) _λ ] ^: ' , the preferred proportions of thiosulfate salt to si lver salt are equal to or greater than 2 moles of thiosulfate salt tor I mole of silver salt The most preferred proportions of thiosulfate salt to silver salt are equal to or greater than 3-to- l In making the aqueous solution of the silver thiosulfate ion complexes, the preferred silver hahde is silver chloride It should be noted that the silver chloride, as well as other silver hahdes can be made /// i/u in the aqueous solution In this wav a water-soluble silver salt such as silver nitrate or si lver acetate is first dissolved in the aqueous solution Λn equivalent oi greater molar amount of a hahde salt containing the chloride ion, such as sodium chloride, potassium chloride, and the like, is then added, resulting in the precipitation of the si lver chloride salt

Additionally in making the aqueous solution of the si lver thiosulfate ion complexes it is preferred that the concentration ot the initial si lv er hahde i n the aqueous solution be less than 25% Higher concentrations of the si lv er hahde can lead to i nstabi lity ot the resulting si lver thiosulfate solution, that is to say, the si lver thiosulfate ion complexes within the solution wil l "break down " or decompose, leading to discoloration of the solution and precipitation of silver sulfide

The second step in the process entails the addition of a solvent to the aqueous solution l esulting from the first step to create a biphasic separation in this wav, the silver thiosulfate ion complexes separate into one phase The preferred solv ents are those which are water miscible Solvents such as ethvl alcohol, isopropvl alcohol methvl alcohol acetone tetrahvdrofuran, and the like, are examples of solvents which are useful in causing phase separation The solvent is added to the silver thiosulfate ion complexes solution in an amount

such that the solution separates into two phases During the formation of two distinct phases, the silver thiosulfate ion complexes separate into one phase Tv picallv, the volume of the phase containing the silver thiosulfate ion complexes is onlv a fraction (e.g. , less than 20%) of the total volume of liquid, this denser liquid phase resembles a liquid mixture containing a heavy oil and an aqueous solution where the heavy oil accumulates at the bottom of the vessel containing the liquid mixture

The phase containing the silver thiosulfate ion complexes is thought to consist of a high concentration (/ e. , 50 - 70% of the total volume) of relatively pure silver thiosulfate ion complexes and water Excess thiosulfate salts, waste salts, solvent, and other contaminants are thought to remain in the other (larger) phase of the biphasic solution

In the third step, the separated phase containing the silver thiosulfate ion complexes can be collected using well known means For example the phase can be drawn up using a pipet and removed from the solution Likewise, a separatorv funnel can be used to separate the phase from the solution

After the liquid phase containing the silver thiosulfate ion complexes has been collected, the fourth step involves treatment of the collected phase to create essentially anhydrous silver thiosulfate complexes The silver thiosulfate complexes are purified, containing insignificant amounts of waste salts (e , sodium nitrate or sodium acetate) and other extraneous materials Treatments which are useful include but are not limited to. evaporation, oven drving, freeze drving, solvent extraction and the like After the treatment, the essentially anhydrous silver thiosulfate complexes are ground into a fine powder

B. Process For Producing Silver Thiosulfate Ion Complexes

When The Ratio Of Thiosulfate Ions To Silver Ions Is Less Than 2-to- l

The process for producing essentially anhydrous si lver thiosulfate ion complexes when the ratio of thiosulfate ions to silver ions is less than 2-to- l involves four major steps The first step, making an aqueous solution of silver thiosulfate ion complexes, is analogous to the

first step of the process where the ratio is greater than 2-to- l The major difference of this process from that where the ratio is greater than 2-to- l is that the second step of this process involves precipitation of the silver thiosulfate ion complexes from the aqueous solution (described below) 5 In the second step, a solvent is added to the aqueous solution of silver thiosulfate ion complexes to precipitate the si lver thiosulfate ion complexes The preferred solvents are those solvents which are water miscible Solvents such as ethvl alcohol, isopropyl alcohol, methyl alcohol, acetone, tetrahydrofuran, etc , are examples of solvents which are useful in causing precipitation The solvent is added to the silver thiosulfate ion complexes solution in an

10 amount such that the complexes precipitate

In the third step, the silver thiosulfate ion complexes precipitate can be separated from the solution using any standard well-known technique Tiltration represents one preferred separation technique The si lv er thiosulfate ion complexes are relatively pure, containing insignificant amounts of waste salts ( g , sodium nitrate or sodium acetate) and other

I 5 extraneous materials like excess thiosulfate salts that are thought to remain in solution (/ e , thev do not form a solid precipitate)

Following separation the fourth and final step of removing essentially al l remnant water from the complexes from the col lected phase creates essential ly anhydrous silver thiosulfate ion complexes Methods which are useful include, but ai e not l imited to,

20 evaporation, oven drying, freeze drving, and the like After the treatment, the essential ly anhydrous si lver thiosulfate ion complexes are ground into a fine powder

C. The Nature Of The Silver Thiosulfate Ion Complexes

While the benefit provided bv the complexes of the present i nv ention is not l imited bv

^ an understanding of the precise nature of the complexes, the solid material produced bv the two processes described above is thought to consist of a salt where the silver thiosulfate ion complexes are represented bv the formulas [Ag(S _: 0,)J ^{1 "} , [ Ag(S _: 0 ₁ ),] ^{> "} [Ag,(S _: 0,),] ⁴ [Ag,( S _: 0,) _t ]" , and similar complexes Unexpectedly, it was found that the form of the si lver thiosulfate ion complexes produced is v ery dependent on the ratio of thiosulfate ion to silvei

If the ratio of the thiosulfate ion to si lver ion is low (/ c , less than 2 1 ), si lver thiosulfate ion complexes represented bv the formulas [Ag (S-,0 ₁ ),] ^4" , [ A.g,(S ₁ 0,) ]" ^" and the

like can be produced The preferred silver thiosulfate ion complexes are those represented by [Ag _: (S ₂ 0,),] ⁴ , which can be produced in accordance with the following chemical equation

3 Na S ₂ 0, ⁺ 2 AgCl → Na Ag ₂ (S ₂ 0,), + 2 NaCl

Conversely, if the ratio of the thiosulfate ion to silver ion is high (/ e., greater than 2 1 ), relatively pure silver thiosulfate ion complexes represented bv the formulas [Ag(S-,0-,) ₂ ]' , [Ag(S ₂ 0,) ₁ ] and the like can be produced

The preferred silver thiosulfate ion complexes are those produced when the ratio of the thiosulfate ion to silver ion is low The purified silver thiosulfate ion complexes are carner- free, photostable, highly water soluble, non-staining and antimicrobiallv active This combination of features is not present in any commercially available or previously described silver-containing composition

II. COMPOSITIONS CONTAINING SILVER THIOSULFATE ION COMPLEXES

Topical antimicrobial agents include therapeutic heavy metal compounds such as silver-containing compounds Silver, in its ionic state ( Ag ), possesses a broad spectrum of antibacterial, antifungal, and antiviral properties and is relatively safe Early studies showed that the silver ion is ohgodynamic. / e , active at verv low concentrations [See genera/ , Russell el al . Antimicrobial Activity and Action of Silver." Progress in Medicinal Chemistry

3 1 35 1 -70 ( 1994)]

The present invention is directed at among other things, carrier-tree silver thiosulfate ion complexes compositions The piovision ot carπei -tree si lver thiosulfate ion complexes is advantageous for at least two reasons First, it provides the ability to make antimicrobial silver thiosulfate ion complexes compositions without the need for potentially irritating porous carrier particles Second it provides the ability to produce antimicrobial silver thiosulfate ion complexes compositions which can contain high concentrations of silver resulting in compositions with potent antimicrobial activitv

As set forth above, the carrier-free silv er thiosulfate ion complexes are stable However, the complexes are not stable in all pharmaceuticallv-acceptable compositions

Indeed, it was found that the silv er thiosulfate ion complexes decompose when incorporated into certain base compositions (See Experimental Section infra) The decomposition of the silver thiosulfate ion complexes results in the silver-based composition both changing to a

black color and losing antimicrobial activity Given the instability of silver thiosulfate ion complexes when incorporated in certain base compositions, it was surprising and unexpected to discover silver thiosulfate ion complexes compositions which were, in fact, stable

The stable si lver thiosulfate ion complexes compositions of the present invention ^ comprise carrier-free suspended silver thiosulfate ion complexes in a base The preferred base is anhvdrous. and in one embodiment the base is semisohd The stable silver-based compositions maintain their antimicrobial activity Moreover, the amount of silver in the compositions can be varied over a large range of concentrations to provide compositions with different levels of antimicrobial potency

10 During the first step of the previously-described process for producing essentially anhvdrous silver thiosulfate ion complexes, an aqueous solution of the complexes is made It should be noted that aqueous solutions of silver thiosulfate ion complexes can be added to an ointment or cream base to make an antimicrobial ointment oi cream composition, in other words, a composition can be made after completing onlv the first of the four steps However,

I the resulting antim icrobial ointment or cream composition suffers from two major drawbacks

First, the resulting silver thiosulfate ion complexes compositions will contain large quantities of excess thiosulfate salts as wel l as waste salts ( g , sodium nitrate, potassium nitrate, and potassium acetate) When applied topical ly, the antimicrobial composition containing these impurities may be irritating The second major problem is that ointment or cream 0 compositions made with si lver thiosulfate ion complexes from such an aqueous solution are not stable for long periods of time That is to sav. over a period of time the resulting silver- based antimicrobial compositions w i l l turn black and lose antim icrobial efficacy

This destabi hzation occurs w hether or not the si lver-based compositions are stored in an opaque containei or a clear container Therefore the destabihzation is not a photo- 5 i eduction of the silv er Rather, w hat occurs is that the thiosulfate ion component of the silver thiosulfate ion complexes experiences a chemical breakdown The effect of this chemical process is the breakdown of the silv er thiosulfate ion complexes

Again, whi le an understanding of the mechanisms i nvolved is not necessary, it is believed that the thiosulfate ion w hich makes up the si lver thiosulfate ion complexes is

30 formed bv adding a sulfur atom to a sulfite ion in a complex reaction that can be summarized bv the fol lowing chemical equation S + SO, ^{~ "} → S.O^ The sulfur atom that is added to the sulfite ion to giv e S 0, ^{2 '} is somewhat labi le, thus, S _: 0, ^: mav appropriately be l epresented as S-SO, ^' In aqueous solutions, thiosulfate decomposes over time At

moderately low pH levels the sulfur atom readilv splits off. nominally yielding sulfur as follows

S-SO, ^{2 "} + H ^{^} → S + HSO,' - While the acid decomposition of the thiosulfate ion nominally yields sulfur, it should be mentioned that very finely divided particles of sulfur in an acidic aqueous solution have the character of polysulfide ions [Levenson Complementarv Processes (Ch 14), in The Theory of the Photographic Process. Fourth Ed MacMillan Publishing Co . Inc . New York ( 1977)]

As a result of the instability of the thiosulfate ion. w hen dissolved in water silver thiosulfate ion complexes also chemically decompose over time It is believed that when the thiosulfate component of the silver thiosulfate ion complexes chemically breaks down, it releases silver ions which react with the released sulfur ions to form silver sulfide Silver sulfide is a black material having the molecular formula of Ag ₂ S Due to si lver sulfide's high dissociation constant ( pK = 49 1 ), silver sulfide is essentially non-antimicrobial That is to sav, the si lver ion is bound tightlv to the sulfur ion so that it can on ly ionize very slowly from the silver sulfide salt As a result, little, if any, ionized si lver is available to provide antimicrobial activity

Likewise, silver thiosulfate ion complexes, when added to either an ointment base which contains a small proportion of water or a water-containing cream base in order to form an antimicrobial composition, w i l l decompose over a i elativ ely short period of time The l esuiting antimicrobial composition wi l l turn black as the si lver thiosulfate ion complexes in the composition decompose to silver sulfide \ddιtιonal lv the composition will lose its antimicrobial efficacy with decomposition ot the silver thiosulfate ion complexes

In contrast, the previously described four-step process for producing essential ly anhvdi ous si lver thiosulfate ion complexes al lows the production of compositions that are stable over long periods of time The stable si lver thiosulfate ion complexes compositions of this invention comprise carrier-free suspended silver thiosulfate ion complexes in a base The bases which ai e most useful for the present invention entai l any compound or m ixture which is capable of suspending the complexes Preferablv, the base is essential ly anhvdrous and can be used topical ly to deliver a medicinal agent By wav of i llustration, bases that are useful include white petrolatum, Aquaphor" ointment base, polaxomers. and polvethvlene glycol

( PEG) polymers with molecular weights greater than 600 The preferred base is a PEG ointment composition containing a combination of PEG polymers with molecular weights greater than 1 000 and polaxomers

The methods for suspending the purified silver thiosulfate ion complexes, in the form of a fine powder, into a base to form a silver-based antimicrobial composition are well known in the art For example, one method involves heating the base until it has liquefied, then, while the base cools, adding the silver thiosulfate ion complexes and stirring until the base has resolidified This method produces a suspension of the silver thiosulfate ion complexes within the base, preferably a homogeneous suspension

The concentration of the silver thiosulfate ion complexes within the base is such as to provide antimicrobial activity The preferred concentration of the si lver thiosulfate ion complexes is 0 1% to 3 0% However, silver thiosulfate ion complexes concentrations can range up to 10% to 30% depending on the antimicrobial potency required The most preferred concentration is between 0 2% and 1 5% Generally speaking, the effective concentration is that concentration w hich is higher than the minimum inhibitory concentration for a particular microbe Vs would be expected, certain m icrobes are more sensitive to silver than other microbes, g , gram (-) microbes are generally more sensitive than gram (+) microbes As a result, a concentration less than 0 1 % could be effectiv e depending on the microbe and the intended use of the final product

The resulting silver thiosulfate ion complexes compositions of the present invention are antimicrobiallv active and stable when compared to compositions that use bases which ai e not anhvdrous Additionally, the silver-based antimicrobial compositions of this invention show no photo-discoloration when exposed to ambient room light over a 72 hour period

Though the compositions must be in an anhvdrous base in order to maintain their stabihtv it is not intended that the compositions ot the present invention be l imited bv the particular nature of the therapeutic preparation For example the present invention contemplates compositions that include physiological ly tolerable di luents, adjuvants and excipients. such as pharmaceutical grades of mannitol, lactose starch, magnesium stearate. sodium saccharin, cellulose, magnesium carbonate, and the like These compositions typically contain l %-95% of active ingredient preferablv 2%-70% In addition, if desu ed the compositions may contain minor amounts of auxiliary substances such as stabilizing or pH buffering agents or preservatives

III. THERAPEUTIC USE OF COMPOSITIONS CONTAINING SILVER THIOSULFATE ION COMPLEXES

The silver thiosulfate ion complexes compositions of the present invention can be used topically, for example, on skin, in wounds, in the eyes, nose, and mouth, in the treatment and ^ prevention of infection As alluded to above, the compositions are effective against bacteria, viruses, and fungi For example toll and manv species of Klehsiella, Proteus, Pseiidomonas, Slaphy/ococciis and Candida may be inhibited or killed by the compositions of the present invention In general, the dosage required for therapeutic efficacy will vary according to the microbe involved, the type of use and mode of administration, as well as the

10 particularized requirements of individual hosts

The therapeutic preparations can be administered for clinical use in humans and for veteπnarv use, such as with domestic animals in manners known in the art and similar to other therapeutic agents Though not limited to any particular means of application, the antimicrobial compositions can be applied using gloved hands or by an applicator Likewise.

I 5 the antimicrobial compositions can be applied to the surface of a dressing, which can then be applied topically Ophthalmic infections can be treated using standard procedures in the art, such as bv pulling down the lower evehd to form a pocket and applying the composition thereto By way of further i llustration, infections of the mouth can be treated bv applying the composition with a sponge applicator or a toothbrush 0 Bacterial resistance to si lver is known to occur in certain situations, more specifically, schei ichia toll and Salmonella i\phιmιtι mm are known to develop plasmid-encoded l esistance to silver [Russell el al Progress in Medicinal Chemistrv 3 1 35 1 -70 ( 1 994)] Two t elated methods are commonly used to prevent and combat drug resistance

The first method entails the combination of two or more therapeutic agents into a final ^ composition For example the β-lactamase inhibitor clav ulanate potassium has been added to amoxicilhn, resulting in a combination preparation (Augmentin™ SmithKhne Beecham) with expanded antimicrobial activity While clavulanic acid has only weak antibacterial activity when used alone its combination with amoxicilhn results in a svnergistic effect

The second method entails the concomitant administration of two or more distinct

30 antimicrobial agents This method is based on the principle that a microbe that is resistant to one agent mav be susceptible to another This is especially important e g , in tuberculosis which is caused bv Mvcohactet nim niherculosis Particular Λ/ liihei ciilosis bacteria that cause tuberculosis are known to displav resistant to each of the pπmarv therapeutic agents As a

result, treatment of tuberculosis often requires combinations of three or more drugs for periods exceeding one year [See Dooly el al "Multidrug-resistant tuberculosis," Ann Int Med 1 17 257-59 ( 1992), Nadler "Multidrug resistant tuberculosis, " N Eng J Med 327 1 1 72-75 ( 1992)] The present invention contemplates combining a topical silver-containing preparation with another medicinal agent to form a pharmaceutical composition Indeed, the present invention contemplates the use of many diverse medicinal agents, including antimicrobial agents topically active drugs, and svstemicallv active drugs The preferred medicinal agents contemplated for use in the pharmaceutical compositions of the present invention are those that can be used as antimicrobial agents in the treatment and prevention of infection and disease Suitable antimicrobial agents include, but are not limited to penicillin, tetracvchne, oxvtetracvchne chlortetracvchne chioramphenicol chlorhexidine mupirocin metronidazole miconazole acvclovir itraconazole and sultonamides Additional antimicrobial agents include antimicrobial peptides such as magainins, cecropins. protegπns, bactenocins and defensins The phaimaceutical compositions of the present invention possess an additional broad spectrum of antimicrobial protection by combining antimicrobial medicinal agents in a stable fashion with silver thiosulfate ion complexes Furthermore as previously indicated, the use of silver thiosulfate ion complexes with an antimicrobial medicinal agent mav aid in preventing the formation of drug-resistant microbes Moreover, since silver ions are oligodvnamic and are not immediately exhausted (/ e thev have a long-lasting or "residual" effect), the presence of silver ions in the pharmaceutical compositions results in compositions which are longer lasting than those containing a single antimiciobial agent

Medicinal agents besides antimicrobial agents are also contemplated for use in the pharmaceutical compositions of the present invention including topically active drugs for the treatment of diseases Suitable topically activ e drugs include but are not limited to. acne preparations such as isotretinoin benzovl peroxide, sahcvhc acid and tetracvchne, anesthetics for topical administration such as dibucaine. hdocaine, benzocaine. tetracacine, deperodon and pramoxine hvdrochloπde, anti-inflammatorv agents such as betamethasone benzoate betamethasone valerate desomde fluocinolone acetonide halcinomde hvdrocortisone. antiperspirants and medications used in the treatment ot hv perhidrosis such as glutaraldehvde, methenamine, glycopyrrolate. scopolamine hvdrobromide. antipruπtic and external analgesic agents such as camphor, menthol sahcvhc acid methvlsa cv late, cleansing agents such as soaps and shampoos, keratolvtic cv totoxic, and destructi e agents such as anthrahn,

canthaπdin. fiuorouracil, podophyllotoxin. resorcinol, and pigmenting an ^" d" 3e'p ^* i^rrιerιtmg agents, sunscreens such as hvdroquinone. monobenzone. tπoxsalen and /?-amιnobenzoιc acid, anabolic steroids for building up tissues under wound healing such as methandienone, proteolvtic agents for the decomposition of fibrin such as trvpsin, vasodilating substances for improving the flow of blow during wound healing such as tolazohne. thrombosis-hampering substances such as heparin. certain biologicallv active substances which affect tissue formation and tissue stabilization such as ascorbic acid and EGF (epidermal growth factor), EGF-URo ( EGF-urogastron). somatostatin. somatotropin asellacnne. and TGF, and mucolvtic and antiviral medicaments which are globulins such as lysozyme A pharmaceutical composition with a broad spectrum of antimicrobial protection is produced by combining one or more topically active drugs in a stable fashion with a pharmaceutical composition containing si lver thiosulfate ion complexes In situations where the topical ly active drugs ai e used to treat a disease which has an abundance of dead tissue ( e g , a fungating tumor or a decubitus ulcer), the addition ot antimicrobial si lver ions wi l l aid in the prevention of a secondary infection at the diseased site Furthermore, the presence of ionized si lver in the pharmaceutical composition can aid in the prevention of malodor caused by anaerobic and aerobic microbes at the diseased site Finally, combining a topically active drug with the si lver thiosulfate ion complexes minimizes the need to apply additional topical antimicrobial compositions which may be incompatible with the medicinal agent, resulting in both time and cost savings

In addition to medicinal agents which are antimicrobial agents or topical l ^y active agents the present invention also contemplates the use of svstemical lv active drugs in the pharmaceutical compositions of the present invention The svstemical lv active drugs are absorbed bv the bodv surface when appl ied topical ly, either neat or w ith the aid of a solvent Suitable svstemical lv active drugs include, but are not lim ited to. sedatives and hypnotics such as pentobarbital sodium, phenobarbital, secobarbital sodium, carbromal, and sodium phenobarbital, psychic energizers such as 3-(2- l -amιnopropvl )-ιndole acetate and 3-(2- ammobutvl )-ιndole acetate, tranquihzers such as reserpine. chlorpromazine hvdrochlonde, and thiopi opazate hvdrochlonde, hormones such as adrenocorticosteroids. for example, 6- - methvlprednisolone. cortisone, cortisol, and tπamcinolone. androgenic steroids, for example, methvl-testosterone. and fluoxvmesterone. estrogenic steroids, for example, estrone, l 7β-estradιoi and ethinyl estradiol, progestational steroids, for example 1 7-α- hvdroxvprogesterone acetate, medroxvprogesterone acetate. 1 9-norprogesterone. and

norethindrone. and thvroxine. antipyretics such as aspirin, sahcylamide. and sodium sahcylate. antispasmodics such as atropine. methscopolamine bromide, and methscopolamine bromide with phenobarbital. antimalaπals such as the 4-amιnoquιnohnes, 8-amιnoguιnohnes, and pyπmethamine, and nutritional agents such as vitamins, essential amino acids, and essential 5 fats

A pharmaceutical composition with a broad spectrum of antimicrobial protection is produced by combining one or more svstemicallv active drugs in a stable fashion with silver thiosulfate ion complexes The addition of silver thiosulfate ion complexes with one or more svstemicallv active drugs to produce a pharmaceutical composition assists in the preservation 10 of the pharmaceutical composition bv protecting it from microbial proliferation and overgrowth, which could otherwise lead to spoilage of the medicinal composition containing the svstemicallv active drugs

Finally, the antimicrobial compositions mav be useful in making infection-resistant cosmetics and personal care products I S

IV. INCORPORATION OF SILVER THIOSULFATE ION COMPLEXES INTO MATRICES AND THE USE OF SUCH MATRICES This section describes the incorporation of silver thiosulfate ion complexes into matrices, most preferably anhvdrous polymeric matrices In turn the matrices products can 0 be used in conjunction with medical devices for the treatment and prevention of infections and diseases In general the silver thiosulfate ion complexes can be incorporated into the polvmer matrix either ( i ) during the production of the polvmer matrix or ( u ) after the polvmei matrix has been produced It is most preferred that the complexes are homogeneously dispersed in the matrix

A. The Nature of Silver Thiosulfate Ion-Containing Anhydrous

Polymeric Matrices Similar to the situation described above regarding compositions, aqueous solutions of silver thiosulfate ion complexes which have not been purified can be incorporated into 30 polvmer matrices to render the matrices compositions antimicrobial However, the resulting matrices compositions will contain large quantities of excess thiosulfate salts as well as waste salts such as sodium nitrate, potassium nitrate, potassium acetate, etc As set forth above, these impurities mav be irritating when the matrices compositions are applied topically

Furthermore the presence of the waste salts mav have a negative impact on the physical characteristics (e g, feel, strength, and stiffness) of the final matrices compositions

The purified carrier-free silver thiosulfate ion complexes of this invention can be incorporated into an anhvdrous polvmer matrix to produce photostable antimicrobial matrices ^ compositions, these compositions are useful in making medical devices The present invention contemplates that anv solid material that does not contain a significant amount of water mav be used as an anhydrous polymer matrix The preferred anhvdrous polymer matrix material is anv material that is compatible (/ e , does not contain reactive components which could lead to the destruction of the thiosulfate hgand, thereby destabilizing the silver 0 thiosulfate ion complexes) with the silver thiosulfate ion complexes of this invention The most preferred polvmer matrix material is one that is compatible with the silver thiosulfate ion complexes of this invention and has some capacity to absorb and/or swell in the presence ot water the ability ot the polvmer matrix to absorb and/or swell in the presence ot water assists in the dissolution and diffusion of the silver thiosulfate ion complexes from the polymer matrix

It should be noted that the silver thiosulfate ion complexes of the present invention can be used with anhvdrous polymer matrices which do have reactive components as long as the media is such that the reactive chemical component of the polymer matrices cannot react with the silver thiosulfate ion complexes For example when incorporated into a solution of 0 alginate material (which contains a number of chemical reactive groups such as carboxvhc acid) the silver thiosulfate ion complexes of the resulting composition are unstable ov er long periods the water in the solution acts as a media in which the reactiv e groups ot the alginate materials can destabilize the silver thiosulfate ion complexes However when the alginate material is dry the silver thiosulfate ion complexes l emain stable ^ Anhvdrous polvmer matrix materials useful in this invention include, but are not limited to the following adhesi es such as acrvhc-based pressure-sensitive adhesives biopolvmers such as silk alginate materials, etc , hydrocolloid materials such as sodium carboxvmethvlcellulose either alone or when bound in a polvmer, polvmers such as polvurethane, sihcone. etc in the form of coatings, films oi foams and the like These 0 anhvdrous polvmer matrix compositions can be used alone or as a component of another material such as a medical device

The concentration of the silv er thiosulfate ion complexes within the anhvdrous polymeric matrix should be such as to provide antimicrobial activity The preferred

concentration of the silver thiosulfate ion complexes in the final polvmeπc matrix is 0 1% to 3 0% However, silver thiosulfate ion complexes concentrations can range up to 10% to 30%, depending on the antimicrobial potency required and the permeability of the polymeric matrix The most preferred concentration is between 0 2% and 1 5% The resulting silver thiosulfate ion complexes-containing matrices compositions of this invention are antimicrobially active and stable Additionally, the compositions of this invention show no photo-discoloration when exposed to ambient room light over a 72-hour period

It should be noted that the silver thiosulfate ion complexes-containing matrices compositions of the present invention can be used alone in the treatment and prevention of infection in a manner analogous to the compositions described above Moreover, as previously alluded to, the matrices compositions can be used to make medical devices such as dressings, tamponades. etc which can be used in the treatment and prevention of infection

B. Incorporation During Production Of Polymer Matrix

The method of incorporating the silver thiosulfate ion complexes during the production of the polymer matrix itself will be dependent on the production process for that polymer matrix The methods of incorporation for several polvmer matrices follows Of course, deviations from these methods as well as the use of different matrices than those specifically mentioned are within the scope of the present invention

The first method of incorporation is useful if the polvmer matrix is produced from a solvent solution of polvmer matrix material In this situation the si lv er thiosulf ate ion complexes in a solid powder form can be added to that solution and mixed thoroughl ^y I pon elimination of the solvent through standard means in the art the remaining polvmer matrix material w ill hav e the silver thiosulfate ion complexes dispersed, preferablv the complexes are dispersed homogeneously For example, in an adhesive material dissolved in a solvent, the silver thiosulfate ion complexes in a powder form are thoroughly mixed in The mixture is then coated on a liner and dried The resulting adhesive film has the silver thiosulfate ion complexes incorporated as a dispersion

Another method of incorporation is useful if the production process for the polymer matrix involves the use of water as a solvent. (/ e . latex polvmer systems, solvent extraction svstems) or as a reactant (/ e , polvurethane foam production, alginate fiber production, etc ) With this method, the silver thiosulfate ion complexes can be dissolved in the water prior to the production process To illustrate, if a polvmer film is being produced bv coating with a

polvmer latex solution, the silver thiosulfate ion complexes can be added directlv to the latex solution Once added, the silver thiosulfate ion complexes will dissolve After coating and drving, the resulting polymer film will have the silver thiosulfate ion complexes homogeneously dispersed in the film

Likewise, in producing a polyurethane foam matrix bv reacting the polyurethane prepolvmer with water, the silver thiosulfate ion complexes can be dissolved in the water prior to reacting it with the prepolvmer After the polvurethane foam has reacted and been dried, the silver thiosulfate ion complexes will be dispersed throughout the foam matrix

Additionally, in producing a water insoluble alginate material bv reacting an alginate solution with an aqueous calcium chloride bath, the silver thiosulfate ion complexes can be dissolved in either the water making up the alginate solution or the calcium chloride bath The alginate solution when extruded into the calcium chloride bath w ill result in crosshnked alginate fibers which incorporate the silver thiosulfate ion complexes Upon drving of these fibers, the silver thiosulfate ion complexes will be dispersed throughout the alginate matrix

Another method of incorporation can be used in conjunction w ith the production of polymer matrices such as a hvdrocolloid matrix made up ot a hvdrocolloid material (e.g , carboxvmethvlcellulose) in a polvmei binder In this situation, the silver thiosulfate ion complexes, in a solid form, can be mixed directly with the hvdrocolloid material prior to the production process Likewise, the silver thiosulfate ion complexes can be dissolved in water which is then used to treat the hvdrocolloid material so that the solution is absorbed bv the hvdrocolloid material and then dried Thereafter, the treated hvdrocolloid material is processed using standard procedures to produce the hvdrocolloid polvmer matrix which contains the silver thiosulfate ion complexes dispersed in the hvdrocolloid component of the matrix

C. Incorporation After Production Of Polymer Matrix

In addition to incorporation prior to or during the production of the polvmer matrix, silver thiosulfate ion complexes can be incorporated after the polvmer matrix has been produced One approach is to form an aqueous solution ot the silver thiosulfate ion complexes and then apply this solution to the finished polv mer matrix This silver thiosulfate ion complexes solution can be applied to the polvmer matrix bv spraving, dipping, painting or other suitable means

By wav of illustration, an aliquot of the silver thiosulfate ion complexes can be applied onto and absorbed into a finished foam dressing After drv ing, the silver-based foam

composition will be stable and antimicrobial Likewise, the silver thiosulfate ion complexes solution can be sprayed on the surface of a polymer or adhesive film which, after drying, will be stable and antimicrobial

D. Precautions During Incorporation

Regardless of the method of incorporating the silver thiosulfate ion complexes with the polymeric matrix, certain precautions need to be considered First, if incorporation of the silver thiosulfate ion complexes into the polymeric matrix involves the use of water, it is very important that the water be removed from the polymeric matrix If the water is not removed, the silver thiosulfate ion complexes will become destabilized within the polymeric matrix over

Second, though the water can be removed using anv standard method, if the water is l emoved bv drving the polymeric matrix in an oven, care should be taken to use only moderate temperatures, temperatures of 20°C to 70°C mav be used, while temperatures of 30°C to 50°C are preferred If the temperature becomes too hot. rapid destabihzation of the silver thiosulfate ion complexes can occur

Finally, when the silver thiosulfate ion complexes are in solution, contact with metai surfaces should be avoided The silver thiosulfate ion complexes solution can be destabilized upon contact with metal surfaces such as aluminum and copper An effort should be made to ensure that the solution comes into contact with materials such as glass or plastic, which appear to be less destabilizing

EXPERIMENTAL

In the disclosure which follows, the following abbreviations apply L (liters), ml ( milhhters), μl (microhters ), g (grams), mg (milligrams), μg (micrograms), mol (moles), mmol (milhmoles), μmol (micromoles), cm (centimeters ), mm ( millimeters), nm ( nanometers), °C (degrees Centigrade), MW and M W (molecular weight), N (normal), w/w ( weight-to-weight), w/v (weight-to- olume). mm (minutes). No (number), ICP (inductively coupled plasma), CFU (colony forming units), PEG (polyethylene glycol), MHM (Mueller Hmton Medium ), ZOI (zone of inhibition), ATCC (American Tvpe Culture Collection.

Rockv ille. MD), USP (United States Pharmacopeia), NCCLS (National Committee for Clinical Laboratory Standards), NIOSH (National Institute of Safety and Health), Avitar (Avitar, Inc . Canton. MA), Aldπch (Milwaukee. WI). Averv Denmson. Inc (Mill Hall, PA),

BASF (BASF Corp , Chemical Division, Parsippany, NJ), Belersdorf Inc (BDF Plaza Norwalk. CT), Columbus (Columbus Chemical Industries. Columbus. WI), Cook Composites and Polymers (Kansas Citv, MO), Difco (Difco Laboratories, Detroit, MI), Hampshire (Hampshire Chemical Co . Lexington, MA), Johnson & Johnson Medical, Inc (Arlington, Tx), Owen Laboratories (San Antonio, TX), Protan (Drammen, Norway), Roundy (Roundy s

Inc , Milwaukee, WI), Sigma (Sigma Chemical Company, St Louis, MO), SmithKline Beecham (Philadelphia, PA), Stenseal (Steπseal Ltd, England), Whatman (Whatman International Ltd , England). WOHL (Wisconsin Occupational Health Laboratory, Madison, WI) The following examples serve to illustrate certain preferred embodiments and aspects of the present invention and are not to be construed as limiting the scope thereof The experimental disclosure which follows is divided into I) Processes To Obtain Silver Thiosulfate Ion Complexes. II) Compositions Containing Silver Thiosulfate Ion Complexes, III) Antimicrobial Activity Of Compositions Containing Silver Thiosulfate Ion Complexes, IV) Use Of Silver Thiosulfate Ion Complexes in Medical Devices, and V) Use Of Silver

Thiosulfate Ion Complexes in Combination With Other Medicinal Agents

I. PROCESSES TO OBTAIN SILVER THIOSULFATE ION COMPLEXES

EXAMPLE 1

Process For Making Silver Thiosulfate Ion Complexes Using Silver Chloride When The Ratio Of Thiosulfate Ions To Silver Ions Is Greater Than 2-to- l

This example il lustrates the process for producing silver thiosulfate ion complexes when the ratio of thiosulfate ions to silver ions is greater than 2-to- l That is. a biphasic separation is employed in this example

The silver thiosulfate ion complexes were produced bv first making a silver chloride precipitate in an aqueous solution (hereafter, "silver chloride precipitate/aqueous solution" ) The silver chloride precipitate/aqueous solution was made bv mixing 20 ml of a silver nitrate (Aldrich. deionized water as the diluent) solution ( 1 mmol/ml) with 22 ml of a sodium chloride solution ( 1 mmol/ml) (Aldrich, deionized water as the diluent) in a 500 ml separatorv funnel To the resulting silver chloride precipitate/aqueous solution was added 60 ml of a sodium thiosulfate (Columbus, deionized water as the diluent) solution ( I mmol/ml) The

resulting mixture was agitated by shaking the separatorv funnel until all of the silver chloride precipitate was dissolved

The silver thiosulfate ion complexes produced were separated by adding 200 ml of ethvl alcohol to the container Upon addition of the ethvl alcohol, the solution became cloudv and separated into two separate phases The two phases were separated using the separatorv funnel The weight of the material in the phase containing the silver thiosulfate ion complexes was approximately 1 7 g This phase was then treated by adding 70 ml ethyl alcohol and 40 ml of acetone to make the silver thiosulfate ion complexes essentially anhydrous After sitting overnight, the silver thiosulfate ion complexes were in the form of a pure, white solid material in the bottom of the container Thereafter, the solvent was decanted and the white solid was dried in an oven (62°C) and ground to a fine white powder using a mortar and pestle The weight of the dried silver thiosulfate ion complexes was 1 0 03 g

The silver thiosulfate ion complexes were analyzed for silver, sodium and sulfur using Inductively Coupled Plasma Argon Emission Spectrometrv The analysis, performed by

Wisconsin Occupational Health Laboratory (WOHL), included measurement of the amount of silver using a method based on NIOSH S I 82 Bπeflv, a representative portion of the silver thiosulfate ion complexes was weighed and diluted 1/1000 in a dilute nitric acid solution Thereafter, an aliquot of the sample was analvzed (Jarrel ASH ICP. Franklin, MA), the analysis gave the following results (expressed as percentages of the air dried samples)

Silvei 20%

Sodium 1 7%

Sulfur 32%

The results of the analvsis suggest that the silver thiosulfate ion complexes were l elatively pure and corresponded to the formula Na H[Ag( S ₂ 0,),] (Silver 20 I 1 % (w/w), Sodium 1 7 13% (w/w), Sulfur 3 s 75% (w/w))

The calculated yield of si lver thiosulfate ion complexes using the process of this example is 93 7%

EXAMPLE 2

Process For Making Silver Thiosulfate Ion Complexes Using Silver Chloride When The Ratio Of Thiosulfate Ions To Silver Ions Is Equal To 2-to- l

^ This example illustrates the process for producing silver thiosulfate ion complexes when the ratio of thiosulfate ions to silver ions is equal to 2-to- l The silver thiosulfate ion complexes were isolated through the use of a biphasic separation

In this example, silver thiosulfate ion complexes were produced by first making a silver chloride precipitate in an aqueous solution bv mixing 10 ml of a silver nitrate (Aldrich, 0 deionized water as the diluent) solution ( 1 mmol/ml) with 10 mi of a sodium chloride

(Aldrich, deionized water as the diluent) solution ( 1 mmol/ml) in a 100 ml specimen container To this silver chloride precipitate/aqueous solution was added 20 ml of a sodium thiosulfate (Columbus, deionized w ater as the diluent) solution ( I mmol/ml ) The resulting mixture was agitated bv shaking the container until all of the silver chloride precipitate was dissolved

Thereafter, the silver thiosulfate ion complexes were separated bv adding 50 ml of acetone to the container Upon addition of the acetone, the solution became cloudv and separated into two separate phases The two phases were separated into individual containers using a pipet The phase containing the silver thiosulfate ion complexes was treated bv 0 adding 50 ml of acetone to make the silver thiosulfate ion complexes essentially anhvdrous

After sitting overnight, the si lver thiosulfate ion complexes were in the form of a pure w hite solid material Thereafter the solvent was decanted and the white solid w as dried in an cwen (62°C) and ground to a fine w hite powder using a mortar and pestle The weight of the dried silver thiosulfate ion complexes was 3 97 grams ^ The resulting silver thiosulfate ion complexes material was analyzed for silver, sodium and sulfur using an Inductively Coupled Plasma (ICP, described above) The analvsis gave the following results

Silver 25%

Sodium 17% 0 Sulfur 30%

The results of the analysis indicate that the silver thiosulfate ion complexes were l elatively pure corresponding with the following theoretical formula NaJAg(S ₂ 0,) ₂ ] ^« 2HoO (Silver 24 7% (w/w), Sodium 1 5 78% (w/w), Sulfur 29 3% (w/w))

The calculated yield of making silver thiosulfate ion complexes using the process of this invention is 90 8%

EXAMPLE 3

Process For Making Silver Thiosulfate Ion Complexes Using Silver Chloride When The Ratio Of Thiosulfate Ions To Silver Ions Is Less Than 2-to- l

This example further illustrates the process for pioducing silver thiosulfate ion complexes when the ratio of thiosulfate ions to silver ions is less than 2-to- l As in the preceding example, the silver thiosulfate ion complexes were isolated through the formation of a precipitate rather than a biphasic separation In this example, silver thiosulfate ion complexes were made bv first making a silver chloride precipitate in an aqueous solution by mixing 1 0 ml of a silver nitrate (Aldrich, deionized water as the diluent) solution ( 1 mmol/ml) with 20 ml of a sodium chloride ( Aldrich, deionized water as the di luent) solution ( 1 mmol/m l ) in a 1 00 ml specimen container To this silver chloride precipitate/aqueous solution was added 1 5 ml of a sodium thiosulfate (Columbus, deionized water as the diluent) solution ( I mmol/m l) The resulting mixture was agitated bv shaking the container until all of the silver chloride precipitate was dissolv ed

Thereafter, the silver thiosulfate ion complexes ere precipitated from the solution bv adding ^0 m l of acetone to the containei The precipitated si lver thiosulfate ion complexes were in the foi m of a pure white solid material The solvent was decanted and the white solid was dried in an oven (62°C) and ground to a fine w hite powder using a mortar and pestle

The si lver thiosulfate ion complexes were analyzed for silver, sodium and sulfur using an Inductively Coupled Plasma ( ICP, described above) The analysis gave the following r esults

Silver 32%

Sodium 14%

Sulfur 29%

The results of the analysis indicate that the silver thiosulfate ion complexes were relatively pure corresponding with the following theoretical formula Na ₄ [Ag ₂ (S ₂ 0,),]*H ₂ 0 (Silver 32 6% (w/w) , Sodium 1 3 9% (w/w). Sulfur 29 0% (w/w))

EXAMPLE 4 Process For Making Silver Thiosulfate Ion Complexes Using Silver Bromide

In making the aqueous solution of silver thiosulfate ion complexes, the preferred silver hahde is silver chloride (Examples 1 -3 ) this example illustrates that other silver hahdes mav be used In this example, the silver thiosulfate ion complexes were produced bv first making a silver bromide precipitate in an aqueous solution (hereafter "silver bromide precipitate/aqueous solution") bv mixing 2 ml of a silver nitrate (Aldrich. deionized water as the diluent) solution ( I mmol/ml) with 2 2 ml of a sodium bromide (Aldrich, deionized water as the diluent) solution ( 1 mmol/ml) in a 50 ml beaker To this si lver bromide precipitate/aqueous solution was added 6 0 ml of a sodium thiosulfate (Columbus, deionized water as the diluent) solution ( I mmol/ml ) The resulting mixture was agitated bv stirring until all of the sodium bromide precipitate w as dissolved

The silver thiosulfate ion complexes were separated bv adding 20 0 ml of acetone to the container Upon addition of the acetone the solution separated into two phases The phase containing the silver thiosulfate ion complexes was collected and treated bv adding 7 0 ml ethvl alcohol and 4 0 ml of acetone to make the silver thiosulfate ion complexes anhvdrous After sitting overnight the silver thiosulfate ion complexes were in the form ot a white solid material at the bottom of the container The solvent was decanted and the white solid was dried in an oven (62°C) and ground to a fine w hite powder using a mortar and (nestle The resulting weight of the dried silver thiosulfate ion complexes was 0 88 g

EXAMPLE 5

Process For Making Silver Thiosulfate Ion Complexes Devoid Of A Phase Separation Procedure

To illustrate the importance of making silver thiosulfate ion complexes using the processes of this invention, silver thiosulfate ion complexes were made by a process which did not use a phase separation procedure when the ratio of thiosulfate ions to silver ions is greater than 2-to- l

This comparison process was performed by first making a silver chloride precipitate in an aqueous solution (hereafter, "silver chloride precipitate/aqueous solution") by mixing 2 ml of a silver nitrate (Aldrich, deionized water as the diluent) solution ( 1 mmol/ml) with 2 2 ml of a sodium chloride (Aldrich, deionized water as the diluent) solution ( 1 mmol/ml) in a 50 ml beaker To this silver chloride precipitate/aqueous solution was added 6 0 ml of a sodium thiosulfate (Columbus, deionized water as the diluent) solution ( 1 mmol/ml) The resulting mixture was agitated bv stirring until all of the sodium chloride precipitate was dissolved

The resulting silver thiosulfate ion complexes solution was placed in a convection oven at 62 °C overnight to evaporate the water The solid material produced had a splotchy tan color with areas which had a deep brown color The lack of a pure white solid indicates that this process leads to a breakdown or decomposition of silver thiosulfate ion complexes

I I. COMPOSITIONS CONTA INING SILVER TH IOSULFATE ION COMPLEXES

EXAMPLE 6

Stable Antimicrobial Composition - PEG Base

The previous examples were directed at processes for making silver thiosulfate ion complexes This example, as well as Examples 7-9 that follow compare various antimicrobial compositions containing the silver thiosulfate ion complexes In this example, a siiver-based antimicrobial composition was produced in a PEG base Specifically, 40 g of a [rølvethvlene glycol (PEG) base (PEG 600 PEG 1000 = 0 3 0 7. Aldrich) was melted While cooling, 0 47 g of the silver thiosulfate ion complexes of Example I were stirred into the melted PEG base The stirring w as continued until the si lv er thiosulfate ion complexes were

homogeneously suspended While stirring, the melted PEG/silver thiosulfate ion complexes composition was cooled to produce a semisohd base The amount of silver in this silver- based antimicrobial composition was equivalent to 0 5% silver nitrate

EXAMPLE 7

Stable Antimicrobial Composition - Aquaphor"

To further illustrate a silver-based antimicrobial composition of this invention, 40 g of Aquaphor" Cholesterohzed Absorbent Eurceπte Ointment Base was melted Aquaphor" is a stable, neutral odorless, anhvdrous ointment base (Belersdorf Inc) While cooling, 1 26 g of the silver thiosulfate ion complexes of Example 1 were stirred into the melted Aquaphor" base The stirring was continued until the silver thiosulfate ion complexes were homogeneously suspended While stirring, the melted Aquaphoi "/silver thiosulfate ion complexes composition was cooled to a semisohd base The amount of silver in this silver- based antimicrobial composition was equivalent to 1 0% silver nitrate

EXAMPLE 8

Stable Antimicrobial Composition - White Petrolatum USP

To illustrate an alternative silver-based antimicrobial composition of the present invention 40 g of white petrolatum USP (Roundv ^' s Pure Petroleum Jell v White Petrolatum USP) w as melted While cooling. 2 52 g of the silver thiosultate ion complexes of Example 1 were stirred into the melted white petrolatum base The stirring was continued until the silver thiosulfate ion complexes were homogeneously suspended Whi le stirring, the melted white petrolatum/silver thiosulfate ion complexes composition was cooled to a semisohd base The amount of silver in this silver-based antimicrobial composition was equivalent to 2 0% silver nitrate

EXAMPLE 9 Stability Of Anhvdrous And Hvdrated Antimicrobial Compositions

This example illustrates the instability of hvdrated silver-based antimicrobial compositions comprising silver thiosulfate ion complexes The experiments of this example

utilize the compositions produced in Examples 6-8. as well as a composition containing a different base. Velvachol " Cream

EXAMPLE 9A PEG Base Plus Water

A hydrated silver-based antimicrobial composition was made where the composition base was PEG The composition was made by mixing 9 g of the silver-based antimicrobial composition of Example 6 with 1 ml of water This silver-based antimicrobial composition contained approximately 10% water by weight

EXAMPLE 9B

Aquaphor" Plus Water

A hydrated silver-based antimicrobial composition was made where the composition base w as Aquaphor" The composition was made bv mixing 9 5 g of the silver-based antimicrobial composition of Example 7 with 0 5 ml of water This silver-based antimicrobial composition contained approximately 5% water

EXAMPLE 9C

White Petrolatum Plus Watei

A hvdrated si lver-based antimicrobial composition was made where the composition base w as white petrolatum The composition was made bv mixing 9 5 g of the silver-based antimicrobial composition of Example 8 with 0 5 ml of water This silver-based antimicrobial composition contained approximately ^% water

EXAMPLE 9D

Velvachol Cream

A silver-based antimicrobial composition containing 0 47 g of the silver thiosulfate ion complexes of Example 1 were stirred into 20 g of Velvachol " (Owen Laboratories)

VelvachoT is a neutral hvdrophihc cream which contains some water (amount unknown) The amount of silver in this silver-based antimicrobial composition was equivalent to 1 0% silver nitrate

The stability of the silver-based compositions of Examples 6 7 8, and 9A-D was evaluated over time The stability of the compositions was determined by measuring the change ot color if anv when the compositions were stored in transparent containers in ambient light Change of color indicates decomposition ot the silver thiosulfate ion complexes Table 1 below indicates the initial color ot each composition and the change in color on days 7 and 14 and after 1 month As depicted bv the results of this study, the silver-based compositions described in

Examples 6 7 and 8 demonstrated no change in color In contrast the hvdrated silver-based compositions Examples 9 A-D demonstrated maior changes in color some after only 7 days (Examples 9B and 9D) all of these compositions / e Examples 9A-D changed from their initial color to a brown or black color Thus the results of this study indicate that the anhydrous compositions of this invention were stable while the analogous hvdrated samples were not

TABLE 1

Stabilin Of Sih cr-Based Composilions

0 III. ANTIMICROBIAL ACTIVITY OF COMPOSITIONS CONTAINING

SILVER THIOSULFATE ION COMPLEXES

EXAMPLE 10

Antimicrobial Activity Of Silver Thiosulfate Ion Complexes s

The /// vino antimicrobial activity was ev aluated bv finding the minimum inhibitory concentration tor the powder of silver thiosulfate ion complexes from Example ^~ This powder was tested in serial two-fold dilutions ranging from I 95 to 250 μg/ml Broth microdilution was performed in serial dilution of the silver thiosulfate powder in tryptic sov ι0 broth (Difco) Each dilution was inoculated with 0 005 ml of a 24-hour growth of a microbe

( 10" to 10 ⁷ CFU/ml) After the dilutions were incubated at 37°C overnight, the lowest dilution of the silver thiosulfate ion complexes that was w ithout evidence of growth (/ e was not cloudv) was the minimum inhibitory concentration ( MIC) reported in terms of μg/ml The results shown in Table 2 demonstrate that the silver thiosulfate ion complexes 3 powder has antimicrobial activity against both gram (+) and gram (-) microbes (Difco)

TABLE 2

EXAMPLE 1 1

Antimicrobial Activity Of Silver-Based Compositions

The antimicrobial activity of the silver-based compositions of Examples 6 7 and 8 were e luated using a zone of inhibition (ZOI) protocol In this ZOI protocol 1 c - diametet discs (Whatman Filter Paper, Quantitative 1 ) were coated with a thin laver of the compositions from Examples 6 7 and 8 These coated discs were placed on Mueller Hinton Medium (MHM, Difco) with lawns of S auretis (ATCC 25923 , 24 hours growth from MFCvl plate) \fter incubation at 36 °C for 1 8 hours, the size of the zone of growth inhibition was measured (in mm ) from the edge of the disc to the point of microbial growth Table 3 shows the ZOI results for each composition on Dav 1 and at one month

TABLE 3

Antimicrobial Of Sih cr-Bascd C ompositions

As can be seen bv the l esults of this studv, the silv er-based compositions of this invention (Examples 6. 7 and 8) demonstrated good antimicrobial activity that was stable for the duration of the studv period That is to sav. the size of the zone of growth inhibition was essentially unchanged over the one month period

IV. USE OF SILVER THIOSULFATE ION COMPLEXES IN MEDICAL DEVICES

EXAMPLE 12 Foam Dressings Containing Silver Thiosulfate Ion Complexes

As previously indicated, the silver thiosulfate ion complexes of the present invention can be used in conjunction with medical devices This example il lustrates the use of silver thiosulfate ion complexes to prepare a medical device made up of a foam polymer matrix In this example, the complexes were incorporated into the matrix during the manufacturing of the polymer matrix

A foam dressing was produced bv first dissolving 0 ^4 g of si lver thiosulfate ion complexes powder in 1 50 m l ot a 0 5 Pluromc L-62 (BASF) aqueous solution This solution was the mixed with 140 g of a polvurethane prepolvmer (Hypol 2002, Hampshire) in a 1 -I ιter disposable plastic beaker The resulting mixture instantly began to react to form a foam After 10 minutes the foam was removed from its container and sliced to produce individual foam dressings (approximately 7 5 cm in diametei The sl ices of foam dressings were dried at 50°C in a dark convection oven

These foam dressings were light stable and antimicrobiallv active In this example and Examples 1 3- 1 8 that follow, the terms "l ight stable " "photostable " and the l ike mean that the samples did not discolor after 72 hours of exposure to ambient room l ight In this example and Examples 1 3- 1 8 that follow the term "antimicrobiallv activ e" means that a small piece ( nominal ly 1 cm x I cm or I cm strands in the case of alginate fibers ) produced zones ot i nhibition when placed on both a lawn of S aiireus ( ATCC 25923 ) and a lawn ot /. toll ( ATCC 25922) The lawns were produced bv plating 24-hour growth microbes on MHM plates after incubation for 24 hours each sample was exam ined to determine whether a zone of inhibition was present

This foam dressing can be used for a large vaπetv ot medical applications, including as an antimicrobial absorptive foam dressing

EXAMPLE 13

Foam Dressing Containing Silver Thiosulfate Ion Complexes

This example further illustrates the use of silver thiosulfate ion complexes to prepare a medical device made up of a foam polymer matrix In contrast to the previous example, the silver thiosulfate ion complexes were incorporated into polvmer matrix following the matrix ^' manufacture

In this example, a foam dressing (Hvdrasorb " Sponge Foam Dressing ( 10 cm x 10 cm), Avitar) was submerged in an aqueous solution containing silver thiosulfate ion complexes powder from Example 3 (0 1 g per liter) The foam dressing samples were removed and dried at 50°C in a convection oven These silver thiosulfate ion complexes- containing foam dressings were light stable and antimicrobiallv active As indicated in the previous example, these foam dressings can be used for a large variety ot medical applications including as an antimicrobial absorptive foam dressings

EXAMPLE 14

Hydrocolloid Dressing Containing Silver Thiosulfate Ion Complexes

This example illustrates the use of the silver thiosulfate ion complexes to prepare a medical device which is made up of a hvdrocolloid absorbent polymer matrix In this example the complexes were incorporated into the matrix during the manufacturing of the polvmer matrix

A hvdrocolloid dressing containing silv er thiosulfate ion complexes was produced bv first thoroughly mixing 0 1 57 g of silver thiosulfate ion complexes powder (mesh 100) from Example 1 with 10 O g of sodium carboxvmethyl cellulose ( Aldrich) Thereafter 4 g of this treated carboxvmethyl cellulose was mixed thoroughly with 4 g of a polyurethane prepolvmer

(Aquapol 035-003 1. Cook Composites and Polvmers) This mixture was then pressed between a polyurethane film and a silicone-treated hvdrocol loid matrix and was al lowed to cure for 24 hours The resulting silver thiosulfate ion complexes-containing hvdrocolloid dressing was photostable and antimicrobiallv activ e This tvpe of dressing is useful on exudating, malodorous wounds

EXAMPLE 15

Hvdrocolloid Dressing Containing Silver Thiosulfate Ion Complexes

This example further illustrates the use of silver thiosulfate ion complexes of this 5 invention to prepare a medical device which is made up of an hvdrocolloid absorbent polymer matrix However, in this example the silver thiosulfate ion complexes were incorporated into the polymer matrix by a different procedure than that presented in the preceding example

The hydrocolloid dressing was produced by first dissolving 0 1 57 g of a silver thiosulfate ion complexes powder (mesh 100) from Example 1 in 10 0 ml of water To this 10 solution was added 100 g of sodium carboxvmethyl cellulose (Aldrich, Milwaukee, WI) which absorbed the solution The treated sodium carboxymethvl cellulose was allowed to dry at room temperature Thereafter 4 g of the dried treated carboxvmethyl cellulose was mixed thoroughly with 4 g of a polyurethane prepolvmer ( Aquapol 035-003 1 Cook Composites and Polymers) This mixture was then pressed between a polyurethane film and a silicone treated I lmer and was allowed to cure for 24 hours

As with the silver thiosulfate ion complexes-containing hvdrocolloid dressing produced in the preceding example the hvdrocolloid dressing is photostable and antimicrobiallv active and is useful on exudating, malodorous wounds

0 EXAMPLE 16

Adhesive Films Containing Silvei Thiosulfate Ion Complexes

This example illustrates the use of silver thiosulfate ion complexes to produce adhesive films Specificallv . a pressure sensitive adhesive (PSA) containing silver thiosulfate ion 5 complexes was produced in this example Adhesive films are. among other things, especially useful in covering painful abrasive-tvpe skin wounds and partial skin graft sites

The silver thiosulfate ion complexes-containing PS A was made bv mixing 0 25 g of the si lver thiosulfate ion complexes powder from Example I in An adhesive solution consisting of 45 g of a proprietary medical grade acrylic based latex (58% solids) (Averv

30 Denmson. Inc ) and 5 g poiyethvlene glycol (M W 600) ( Aldrich) w as first prepared Then

0 25 g of the silver thiosulfate ion complexes powder from Example I was mixed with the adhesive solution, forming an adhesive mixture This adhesive mixture, when coated and dried, produces a tackv. adhesiv e film

The adhesive film is photostable and antimicrobiallv active. This adhesive film can be laminated to dressing backing materials to produce dressings which are antimicrobiallv active. Dressings with the silver thiosulfate ion complexes-containing PSA are especially useful in covering painful abrasive-type skin wounds and partial skin graft sites.

EXAMPLE 17 Alginate Materials Containing Silver Thiosulfate Ion Complexes

This example illustrates the use of silver thiosulfate ion complexes to produce a medical device which is made up of non-adherent alginate material. Specifically, the method of this example involves the use of a calcium chloride bath which results in crosshnked alginate fibers that incorporate the silver thiosulfate ion complexes.

First, water-swellable alginate fibers were produced containing si lver thiosulfate ion complexes. The alginate fibers were made by using a syringe to inject a 5% sodium alginate solution (Pronova LV M Sodium alginate. Protan) into a bath consisting of a 10% calcium chloride solution (Aldrich. deionized water as diluent) containing 0. 1 g/liter silver thiosulfate ion complexes powder from Example 3. The alginate solution immediately formed water- insoluble alginate fibers upon contact with the calcium chloride/silver thiosulfate ion complexes bath. The fibers were pulled from the bath and allowed to dry (50°C). The resulting fibers are photostable and antimicrobiallv active. These fibers can be used to make antimicrobial alginate dressings and tamponades. Alginate materials containing si lver thiosulfate ion complexes are especially useful in covering painful abrasive-type skin wounds and wound ulcers as well as for filling in deep wounds and cavities.

EXAMPLE 18

Alginate Materials Containing Silver Thiosulfate Ion Complexes

To further i llustrate the use of the silver thiosulfate ion complexes of this invention to produce a medical device which is made up on non-adherent alginate material, this example utilizes a method that does not include a calcium chloride bath.

First, an aqueous solution containing 0. 1 g/liter of a silver thiosulfate ion complexes from Example 3 was prepared. The resulting aqueous solution was then applied to a 9.5 cm x 9.5 cm alginate dressing (Steriseal Sorbsan Surgical Dressing. Steriseal ) bv spraving the

solution onto the dressing Alternatively, the silver thiosulfate ion complexes solution can be applied bv dipping the alginate dressing into the solution The alginate fibers of the dressing absorbed the applied solution, thereafter, the treated alginate dressing was allowed to dry (room temperature) The alginate dressing was light stable and was antimicrobiallv active, and, as noted in the preceding example, it is especially useful for malodorous wounds as well as for covering painful abrasive-tvpe skin wounds and wound ulcers

V. USE OF SILVER THIOSULFATE ION COMPLEXES IN COMBINATION WITH OTHER MEDICINAL AGENTS

EXAMPLE 19

Pharmaceutical Composition Combining Mupirocin With Silver Thiosulfate Ion Complexes

To illustrate an antimicrobial pharmaceutical composition consisting of a combination of the silver thiosulfate ion complexes of the present invention with one or more agents, 0 02 g of the silver thiosulfate ion complexes from Example 2 were blended into 2 0 g of a mupirocin ointment (Bactroban " [2% mupirocin acid in a PEG base], SmithKlme Beecham) The mupirocin ointment is a topical antimicrobial with excellent gram (+) antimicrobial properties The silver thiosulfate ion complexes were blended into the mupirocin ointment bv first melting the mupirocin ointment and then stirring the si lv er thiosultate ion complexes into the melted ointment The ointment was stirred continuallv until it cooled and resolidified

EXAMPLE 20

Pharmaceutical Composition Combining Mafenide With Silv er Thiosulfate Ion Complexes

To further illustrate an antimicrobial pharmaceutical composition consisting of a combination of the silver thiosulfate ion complexes of this invention with one or more agents,

0 25 g of mafenide (Sigma) (/ -amιnomethvlbenzesulfonamιde) and 0 25 g of the silver thiosulfate ion complexes of Example 3 were blended into 24 50 g of a PEG composition ("PEG Composition" ), the PEG Composition was produced bv melting together a blend of

40% PEG (M W 3450) and 60% PEG (M W 600) The pharmaceutical composition was produced by first melting the PEG Composition and then stirring in the silver thiosulfate ion complexes and mafenide The resulting pharmaceutical composition was stirred continually until cooled and resolidified The resulting pharmaceutical composition has use as a broad spectrum topical antimicrobial

EXAMPLE 21

Pharmaceutical Composition Combining Metromdazole With Silver Thiosulfate Ion Complexes

To further illustrate an antimicrobial pharmaceutical composition consisting of a combination of the silver thiosulfate ion complexes of the present invention with one or more agents 0 25 g of metromdazole (Sigma) and 0 25 g ot the silver thiosulfate ion complexes of Example 3 were blended into 24 50 g of a PEG composition ("PEG Composition"), the PEG Composition was produced bv melting together a blend of 40% PEG (M W 3450) and 60%

PEG (M W 600) The pharmaceutical composition was produced bv first melting the PEG Composition and then stirring in the silver thiosulfate ion complexes and metromdazole The resulting pharmaceutical composition was stirred continually until it cooled and resolidified This pharmaceutical composition has use as a broad spectrum topical antimicrobial and is especially useful in the treatment of malodorous wounds

EXAMPLE 22

Pharmaceutical Composition Combining Chlorhexidme With Silver Thiosulfate Ion Complexes

To further illustrate an antimicrobial pharmaceutical composition consisting of a combination of the silver thiosulfate ion complexes of the present invention with one or more agents 0 25 g of chlorhexidme diacetate hydrate (Aldrich) and 0 25 g of the silver thiosulfate ion complexes of Example 3 were blended into 24 5 g ot Aquaphoi ^κ (a cholesterolized absorbent Euceπte ^R ointment base produced bv Belersdorf Inc ) The pharmaceutical composition was produced by first melting the Aquaphor" ointment and then stirring in the silver thiosulfate ion complexes and chlorhexidme The resulting pharmaceutical composition

was stirred continually until it cooled and resolidified This pharmaceutical composition has use as a broad spectrum topical antimicrobial

EXAMPLE 23 Pharmaceutical Composition Combining Tnclosan

With Silver Thiosulfate Ion Complexes

To further illustrate an antimicrobial pharmaceutical composition consisting of a combination of the silver thiosulfate ion complexes of the present invention with one or more medicinal agents, 0 50 g of tnclosan (Irgasan DP 300 Ciba-Geigy, Greensboro, NC) and 0 50 g of the silver thiosulfate ion complex of Example 3 were blended into 24 00 g of Aquaphor" (a cholesterolized absorbent Euceπte " ointment base produced bv Belersdorf Inc ) The pharmaceutical composition was produced bv first melting the Aquaphoi " ointment and then stirring in the silver thiosulfate ion complexes and tnclosan The resulting pharmaceutical composition was stirred continually until it cooled and resolidified This pharmaceutical composition has use as a broad spectrum topical antimicrobial

EXAMPLE 24

Pharmaceutical Composition Combining Hvdrocortisone With Si lver Thiosulfate Ion Complexes

To further i l lustrate an antimicrobial pharmaceutical composition consisting ot a combination of the si lver thiosulfate ion complexes ot the present inv ention with one or more agents 0 50 g ot Hvdrocortisone 2 1 - Acetate ( Sigma) and 0 50 g of the si lver thiosulfate ion complexes of Example 3 were blended into 24 00 g ot Aquaphor" (a cholestei oi ized absorbent

Euceπte" ointment base produced bv Belersdorf Inc ) The pharmaceutical composition was produced bv first melting the Aquaphor" ointment and then stirring in the si lver thiosulfate ion complexes and hvdrocortisone The resulting pharmaceutical composition was stirred continual ly until it cooled and resolidified This pharmaceutical composition has use topically as an anti-inflammatorv and an anti-itch treatment which also has antimicrobial properties to prevent a secondary infection when applied topical ly to blistered wounds caused bv dermatitis insect bites, poison IVV, etc

EXAMPLE 25

Pharmaceutical Composition Combining Lidocaine With Silver thiosulfate Ion Complexes

To further illustrate an antimicrobial pharmaceutical composition consisting of a combination of the silver thiosulfate ion complexes of the present invention with one or more agents 0 50 g of lidocaine (Sigma) and 0 50 g of the silver thiosultate ion complexes of Example 3 were blended into 24 00 g of PEG composition ("PEG Composition"), the PEG Composition was produced by melting together a blend of 40% PEG (M W 3450) and 60% PEG (M W ) The pharmaceutical composition was produced bv first melting the PEG

Composition and then stirring in the silver thiosulfate ion complexes and lidocaine The resulting pharmaceutical composition was stirred continually until it cooled and resolidified This pharmaceutical composition has use as a topical anesthetic which also has antimicrobial properties to prevent a secondarv infection when applied to exposed tissues or wounds

EXAMPLE 26

Pharmaceutical Composition Combining Pramoxine With Silver Thiosulfate Ion Complexes

To further illustrate an antimicrobial pharmaceutical composition consisting of a combination of the silver thiosulfate ion complexes ot the present invention with one or more agents I 00 g of pramoxine hvdrochlonde (Sigma) and 0 50 g ot the silver thiosulfate ion complexes of Example 3 were blended into 23 50 g of PEG composition ( "PEG Composition" ), the PEG Composition was produced bv melting together a blend of 40% PEG (M W 3450) and 60% PEG (M W 600) The pharmaceutical composition was produced by first melting the PEG Composition and then stirring in the si lver thiosulfate ion complexes and pramoxine The resulting pharmaceutical composition was stirred continually until it cooled and resolidified This pharmaceutical composition has use as a topical anesthetic which also has antimicrobial propeπies to prevent a secondarv infection when applied to exposed tissues or wounds

From the above, it should be evident that the present invention provides for silver- based antimicrobial compositions and processes for making such compositions that are

suitable for use in the treatment and prevention of infections It should be understood that the present invention is not limited to the specific compositions shown nor to the uses of the compositions described In light of the foregoing disclosure, it will be apparent to those skilled in the art that substitutions, alterations, and modifications are possible in the practice of this invention without departing from the spirit or scope thereof

CLAIMS

I claim

1 An antimicrobial composition, comprising silver thiosulfate ion complexes in a base

2 The composition of Claim 1 , wherein said silver thiosulfate ion complexes are homogeneously suspended in said base

3 The composition of Claim 1 , wherein said base is anhydrous

4 The composition of Claim 1 vv' herein the concentration of said silver thiosulfate ion complexes within said base is from 0 01 % to 30% (w/w )

5 The composition of Claim 1 , wherein the concentration of said silver thiosulfate ion complexes within said base is from 0 1 % to 3 0% (w/w)

6 The composition of Claim 1 , wherein the concentration of said silver thiosulfate ion complexes within said base is from 0 2% to 1 5% (w/w)

7 The composition of Claim 1 , wherein said base is selected from the group consisting of polvethvlene glycol Aquaphor® and white petrolatum

8 The composition of Claim I , wherein said silver thiosulfate ion complexes are derived from the complexation of a silver cation from silver hahdes with anions

9 The composition of Claim 8, wherein said silver hahde comprises silver chloride and said anions comprise sodium thiosulfate salts

10 The composition of Claim 9, wherein the molar ratio of the thiosulfate anions to silver cations is at least 1 1

1 1 The composition of Claim 9 wherein the molar ratio of thiosulfate anions to silver cations is at least 1 3 1

12 A pharmaceutical mixture, comprising a) a medicinal agent, and b) silver thiosulfate ion complexes

13 The pharmaceutical mixture of Claim 12, wherein said silver thiosulfate ion complexes are carrier-free

14 The pharmaceutical mixture of Claim 12, further comprising an anhydrous base

1 5 The pharmaceutical mixture of Claim 13, wherein said base is selected from the group consisting of polyethylene glycol, Aquaphor . and white petrolatum

16 The pharmaceutical mixture of Claim 12 wherein the concentration of said silver thiosulfate ion complexes in said pharmaceutical mixture is from 0 01% to 30%> (w/w)

1 7 The pharmaceutical mixture of Claim 12, wherein the concentration of said silver thiosulfate ion complexes in said pharmaceutical mixture is from 0 1 % to 3 0%o (w/w)

1 8 The pharmaceutical mixture of Claim 12, wherein the concentration of said si lver thiosulfate ion complexes in said mixture is from 0 2% to I 5% (w/w)

19 The pharmaceutical mixture of Claim 12, wherein said medicinal agent of said pharmaceutical mixture is an antimicrobial agent

20 The pharmaceutical mixture of Claim 19, wherein said antimicrobial agent is selected from the group consisting of acvclovir, chloramphemcol. chlorhexidme. chlortetracycline, itraconazole, mafenide, metro dazole. mupirocin. nitrofurazone, oxvtetracychne, penicillin, and tetracvchne

21 The pharmaceutical mixture of Claim 12, wherein said medicinal agent of said pharmaceutical mixture is a steroid

22 The pharmaceutical mixture of Claim 21 , wherein said steroid is selected from the group consisting of betamethasone benzoate, betamethasone valerate, desonide, fluocinolone aceto de, halcinomde, hvdrocortisone, and metandienone

23 The pharmaceutical mixture of Claim 12, wherein said medicinal agent of said pharmaceutical mixture is an anesthetic

24 The pharmaceutical mixture of Claim 23, wherein said anesthetic is selected from the group consisting of benzocaine. dibucaine. lidocaine, pramoxine hvdrochlonde and tetracacine

25 A method of imparting antimicrobial protection, comprising a) providing i ) a product, and n) an effective amount of carrier-free suspended silver thiosulfate ion complexes, and b) applying the effective amount of the carrier-free suspended silver thiosulfate ion complexes in a base to the ob)ect

26 The method of Claim 25 wherein said product is solid

27 The method of Claim 26, wherein said product is a medical device

28 The method of Claim 27 wherein said medical device comprises a matrix

29 The method of Claim 28, wherein said matrix is a polymer

30 The method of Claim 29 wherein said polymer is anhydrous

3 1 The method of Claim 25. wherein product is a personal care product

32 The method of Claim 3 1 , wherein said personal care product is selected from the group consisting of lipsticks, hpgloss, lip pencils, mascaras, eye liners, eye shadows, moisturizers, liquid makeup foundations, powder makeup foundations, powder blushes, cream blushes, perfumes, colognes, toners, deodorants, shaving creams, shampoos, conditioners, hair mousses, hairsprays, toothpastes, and mouthwashes,

33 The method of Claim 28 wherein said personal care product is selected from the group consisting of combs, brushes, sponges, cotton swabs, cotton balls, razors, dental flosses, dental tapes, sunscreens, moisturizers, tampons, sanitary napkins, panty shields, diapers, baby wipes, facial tissues and toilet tissues

34 A device, comprising a medical device coated with an antimicrobial compositions comprising silver thiosulfate ion complexes

35 The device of Claim 34 wherein said medical device is selected from the group consisting of medical implant wound care devices, bodv cavitv and personal protection devices

36 The device of Claim 34 wherein said device is a uπnarv catheter and said silver thiosulfate ion complexes comprise an anhydrous polymer matrix

37 A method of treating or preventing a microbial infection, comprising a) providing l) a subject, said sub|ect either infected or at risk of infection by a topical microbial infection, and n) an effective amount of carrier-free suspended silver thiosulfate ion complexes in a base to form a pharmaceutical mixture, and

b) administering the effective amount of the carrier-free suspended silver thiosulfate ion complexes in a base to the sub|ect

38 The method of Claim 37. wherein said silver thiosulfate ton complexes are carrier-free

39 The method of Claim 37 wherein said base is anhydrous

40 The method of Claim 39 wherein said base is selected from the group consisting of polyethylene glycol. Aquaphor®. and white petrolatum

41 The method of Claim 37 wherein the concentration of said silver thiosulfate ion complexes in said pharmaceutical mixture is from 0 01 % to 30% (w/w)

42 The method of Claim 37 wherein the concentration of said silver thiosulfate ion complexes in said pharmaceutical mixture is from 0 1 % to 3 0% (w/w)

43 The method of Claim 37 wherein the concentration of said silver thiosulfate ion complexes in said mixture is from 0 2% to I 5% (w/w)

44 The method of Claim 37 wherein said pharmaceutical mixture further comprises a medicinal agent

45 The method of Claim 44 w herein said medicinal agent is a microbial agent

46 The method of Claim 45 wherein said antimicrobial agent is selected from the group consisting of acvclovir, chloramphemcol, chlorhexidme, chlortetracycline, itraconazole, mafenide metromdazole, mupirocin nitrofurazone. oxytetracvcline, penicillin, and tetracvchne

47 The method of Claim 44 wherein said medicinal agent of said pharmaceutical mixture is a steroid

48 The method of Claim 47 wherein said steroid is selected from the group consisting of betamethasone benzoate, betamethasone valerate, desonide. fluocinolone acetonide, halcinonide, hvdrocortisone. and metandienone

49 The method of Claim 44 wherein said medicinal agent of said pharmaceutical mixture is an anesthetic

50 The method of Claim 49, wherein said anesthetic is selected from the group consisting of benzocaine, dibucaine, lidocaine, pramoxine, hydrochlonde and tetracacine

51 A method for producing essentially anhydrous silver thiosulfate ion complexes, comprising a) providing an aqueous solution of silver thiosulfate ion complexes. b) adding a solvent to said solution to create a biphasic separation wherein said silver thiosulfate ion complexes separate into a single phase, c) collecting said single phase containing said silver thiosulfate ion complexes, and d) removing water from said single phase such that said silver thiosulfate ion complexes are essentially anhydrous

52 The method of Claim 5 1 wherein the ratio of thiosultate ions to silver ions in said silver thiosulfate ion complexes is greater at least 2 1

53 The method of Claim 52 wherein the ratio of thiosulfate ions to silver ions in said silver thiosulfate ion complexes is less than 3 1

54 The method of Claim 5 1 wherein said aqueous solution is formed by reacting a silver hahde with sodium thiosulfate

55 The method of Claim 54 wherein the molar ratio of silver cations from said silver hahde to thiosulfate anions from said sodium thiosulfate is at least 1 1

56 The method of Claim 55. wherein the molar ratio of silver cations from said silver hahde to thiosulfate anions from said sodium thiosulfate is at least 1 3 1

57 The method of Claim 54. wherein said silver hahde comprises silver chloride

58 The method of Claim 5 1 , wherein said solvent is water-miscible

59 The method of Claim 58, wherein said solvent is selected from the group consisting of ethyl alcohol, isopropyl alcohol, methyl alcohol, acetone, and tetrahvdrofuran

60 A method for producing essentially anhydrous silver thiosulfate ion complexes, comprising a) providing an aqueous solution of silver thiosulfate ion complexes, b) adding a solvent to said aqueous solution to precipitate said silver thiosulfate ion complexes, c) collecting said precipitated silver thiosulfate ion complexes, and d) removing water from said collected silver thiosulfate ion complexes such that said silver thiosulfate ion complexes are essentially anhydrous

61 The method of Claim 60, wherein the ratio of thiosulfate ions to silver ions in said silver thiosulfate ion complexes is less than 2 1

62 The method of Claim 61 wherein the ratio of thiosulfate ions to silver ions in said silver thiosulfate ion complexes is greater than 1 1

63 The method of Claim 60 wherein said aqueous solution of silver thiosulfate ion complexes is formed by reacting silver hahde with sodium thiosulfate

64 The method of Claim 63 w herein the molar ratio of silver cations from said silver hahde to thiosulfate anions from said sodium thiosulfate is at least I 1

65 The method of Claim 63 wherein the molar ratio of silver cations from said silver hahde to thiosulfate anions from said sodium thiosulfate is at least 1 3 1

66 The method of Claim 63 wherein said silver hahde is silver chloride

67 The method of Claim 60 wherein said solvent is water-miscible

68 The method of Claim 67 wherein said solvent is selected from the group consisting of ethyl alcohol, isopropyl alcohol methyl alcohol, acetone, and tetrahydrofuran

nternationa app ication o PC17US97/14697

Box I Observations where certain claims were found unsearchable (Continuation of item 1 of first sheet)

This international report has not been established m respect of certain claims under Article 17(2Xa) for the following reasons

1. I I Claims Nos.:

^~^ because they relate to subject matter not required to be searched by this Authoπty, namely.

2. I I Claims Nos.:

*— ' because they relate to parts of the international application that do not comply with the prescribed requirements to such an extent that no meaningful international search can be earned out, specifically

D Clai s Nos. because they are dependent claims and are not drafted in accordance with the second and third sentences of Rule 64(a)

Box II Observations where unity of invention is lacking (Continuation of item 2 of first sheet)

This International Searching Authoπty found multiple inventions in this international application, as follows

Group I, claims 1-26 and 37-68 a composition and methods of use and production. Group II, claims 27-30 and 34-36 a medical device. Group HI, claims 31-33 personal care products

α As all required additional search fees were timely paid by the applicant, this mteraational search report covers all searchable claims

2. As all searchable claims could be searched without effort justifying an additional fee, this Authoπty did not invite payment of any additional fee.

3. I I As only some of the required additional search fees were timely paid by the applicant, this mteraational search report covers only those claims for which fees were paid, specifically claims Nos..

No required additional search fees were timely paid by the applicant Consequently, this international search report is restricted to the invention first mentioned in the claims; it is covered by claims Nos

Remark on Protest I The additional search fees were accompanied by the applicant's protest

I I No protest accompanied the payment of additional search fees

Form PCT/ISA 210 (continuation of first sheet(l)XJuly 1992)*