HK1076755B - Wound dressing - Google Patents

Description

Wound dressing

The present invention relates to silicone-based compositions, methods of making the compositions, and the use of the compositions in medicine. In particular, but not exclusively, the present invention provides a silicone-based wound dressing.

Skin injuries caused by injury or surgery, such as incisions, trauma, and/or skin lesions, may result in scarring rather than regenerative prototissues. Scars are undesirable because they not only cause embarrassing cosmetic problems, but scar tissue often lacks the function of normal skin. For example, the touch may be degraded or lost altogether, and a light spot may form where scar tissue interfaces with undamaged tissue. Various therapies and treatments have been developed with a view to reducing scar formation and improving existing scars.

Suitably, wound dressings have been developed comprising hydrated plastic films or hydrogels in an attempt to reduce scar formation and prevent pathogen growth at the target tissue of injury. A particular disadvantage of using hydrogel dressings is that they do not conform well to changing body topography and thus apply different pressures at different parts of the body. Suitably, the hydrogel dressing does not completely cover the target tissue site. In addition, since the moisture content of a hydrogel dressing changes with the humidity of the air, thereby changing the effectiveness and longevity of the dressing, a covering or outer film is typically applied over the dressing. In addition, since hydrogel dressings are heavy, inconvenient to use, and very difficult to maintain in the correct position, professional care of a doctor or nurse is often required for proper maintenance.

Suitably, alternative wound dressings have been developed which contain silicone oil, also known as silicone. While silicone oils may exhibit good compatibility with human tissue and exhibit the necessary biological properties, such as allowing moisture, gases and toxins to permeate from the skin while acting as a barrier to potential pathogens, thereby allowing the skin to function properly, generally silicone oils are themselves in the form of free-flowing fluids/oils and do not exhibit the physical consistency necessary to be suitable for use as a wound dressing. In general, the consistency of the thick ointment or grease used in wound dressings should be such that the dressing adheres sufficiently firmly to the underlying target tissue site and needs to be carefully removed from the target site.

To increase the viscosity of silicone oils, wound dressings have been developed that contain a blend of silicone oil and up to about 3% by weight fumed silica. While this blend may provide a consistency superior to that of unblended silicone oils, a higher viscosity blend is generally required to improve adhesion to wounds and prevent staining of the dressing (i.e., stain resistance). However, silicone oil/fumed silica blends that exhibit high viscosity, provide improved adhesion and "anti-fouling" are often difficult to apply to target tissue without causing further damage and/or pain.

In order to reconcile the conflict between improving adhesion to the target tissue site and causing further injury and/or pain, wound dressings have been developed that contain silicone oil, fumed silica, and a volatile diluent. Suitably, the addition of a biocompatible volatile diluent allows the wound dressing to be prepared in the form of an easily spreadable ointment, gel or oil which can be applied to a wound without causing further damage or discomfort. After the blend is placed on the wound, the volatile diluent evaporates from the composition, typically resulting in a higher viscosity product composition that exhibits increased adhesion to the wound and increased resistance to staining. While this composition is helpful in addressing the problem of preparing a silicone oil-based wound dressing of the requisite consistency, a particular problem with such wound dressings is the relatively long time required after application of the composition to the target tissue site before the resulting composition exhibits the desired increased viscosity, adherence and stain resistance. Typically, the evaporation time required may be 15 minutes or more before the composition exhibits sufficient adherence to the target tissue site. As a result, during this period, in order to prevent the composition from slipping off the target tissue site while achieving a desired viscosity, it is necessary to fix the target site or fix the composition to the target site. Suitably, this may reduce the effectiveness and applicability of the composition due to the difficulty of applying the composition to certain parts of the body, particularly parts that are not easily immobilized and not easily accessible. In addition, after application of the composition, it is necessary to wait a considerable period of time until the composition reaches the desired viscosity and the target tissue site needs to be fixed, which may result in decreased patient compliance and necessitate professional application and care by a doctor or nurse.

Accordingly, the present invention seeks to provide improved compositions suitable for application to a target tissue site, in particular a target tissue site susceptible to infection and/or scarring by a pathogen, particularly a skin lesion or wound.

According to a first aspect, the present invention provides a composition comprising a non-volatile silicone fluid in admixture with fumed silica, a volatile diluent and a silicone elastomer. Hereinafter, the composition is referred to as the composition of the present invention.

Suitably, the composition of the present invention is intended to address the aforementioned technical problems associated with the application of a wound dressing to a target tissue site. Unexpectedly, it has been found that the addition of a silicone elastomer to the compositions of the present invention not only produces compositions having substantially the same viscosity as a control composition without the silicone elastomer, but also promotes the evaporation of the volatile diluent from the compositions of the present invention. Suitably, the composition of the present invention evaporates the volatile diluent in a shorter time after application to the target tissue site to achieve the desired higher viscosity, adhesion and stain resistance than a substantially identical composition without the silicone elastomer. Conveniently, there is generally no need to fix the target tissue site or to fix the composition at the target tissue site, and the volatile diluent is evaporated to form a product composition having the necessary viscosity, adhesion and stain resistance to allow it to function as a wound dressing. Suitably, the compositions of the present invention are more effective and applicable than comparative compositions that do not contain silicone elastomers because they can be applied to target tissue on body parts that are not readily accessible or easily immobilized. In addition, the compositions of the present invention may be in the form of an easily spreadable ointment, gel or oil, which may be applied to the target tissue without causing further damage or discomfort. Conveniently, the compositions of the present invention allow for increased patient compliance without the need for professional application and care by a doctor or nurse.

Indeed, the compositions of the present invention may be referred to as "fast-dry compositions" relative to substantially identical compositions that do not contain the silicone elastomer. Although only by theory, it is believed that the silicone elastomer can facilitate evaporation of the volatile diluent from the composition of the present invention.

As used herein, the term "silicone elastomer" refers to a silicone polymer that is capable of substantially recovering shape and size after removal of a stretching force at room temperature without exceeding the elastic limit. Suitably, the silicone elastomer is a thixotropic solid, whereby the viscosity of the silicone elastomer decreases over time when a shear force is applied thereto.

Suitably, the silicone elastomer has a weight average molecular weight of greater than or equal to 150,000, preferably greater than or equal to 200,000, more preferably greater than or equal to 250,000, and more preferably greater than or equal to 300,000.

Preferably, the silicone elastomer comprises a silicone polymer. More preferably, the silicone elastomer is a silicone crosspolymer (i.e., a crosslinked silicone polymer). It is also preferred that the silicone elastomer comprises a dimethicone crosspolymer (i.e., a crosslinked dimethicone polymer). The silicone elastomer, in particular the dimethicone crosspolymer, may be unsubstituted or substituted, for example with a polyether such as polyethylene glycol (PEG). Most preferably, the silicone elastomer, in particular the dimethicone crosspolymer, is unsubstituted.

Suitably, when the silicone elastomer comprises a silicone crosspolymer, the silicone crosspolymer preferably comprises less than or equal to 10 wt% crosslinker, more preferably less than or equal to 8 wt% crosslinker, and even more preferably less than or equal to 5 wt% crosslinker. Preferably, the silicone crosspolymer includes greater than or equal to 1 wt% crosslinker, more preferably greater than or equal to 2 wt% crosslinker.

The compositions of the present invention preferably comprise greater than or equal to 0.1 wt%, preferably greater than or equal to 0.2 wt%, more preferably greater than or equal to 0.25 wt%, more preferably greater than or equal to 0.3 wt%, and most preferably greater than or equal to 0.5 wt% silicone elastomer. The compositions of the present invention preferably comprise less than or equal to 10 wt%, more preferably less than or equal to 5 wt%, more preferably less than or equal to 2 wt%, more preferably less than or equal to 1.5 wt%, most preferably less than or equal to 1 wt% of silicone elastomer. Particularly preferred compositions of the invention comprise between 0.2 and 1% by weight, especially between 0.2 and 0.8% by weight, of silicone elastomer.

Conveniently, for ease of handling, the silicone elastomer may incorporate one or more low viscosity silicone fluids, such as the non-volatile silicone fluids and/or volatile silicone fluids described below, for example linear polydimethylsiloxanes or polycyclomethicones. Suitably, a mixture of silicone elastomer and non-volatile silicone fluid is used to make the elastomer easier to mix with the other components of the composition of the invention, i.e. with the fumed silica, the non-volatile silicone fluid and the volatile diluent.

Preferably, the silicone elastomer is compounded with one or more non-volatile silicone fluids of low viscosity, in particular non-volatile linear polydimethylsiloxanes. As an alternative embodiment, the silicone elastomer is mixed with one or more volatile silicone fluids, in particular a polycyclomethicone, described hereinafter, and specifically decamethylpentasiloxane or dodecamethylhexasiloxane.

It will be appreciated that when a mixture of silicone elastomer and low viscosity silicone fluid is applied to the composition of the invention, the low viscosity silicone fluid in the mixture of silicone elastomer and low viscosity silicone fluid may be the same as the volatile diluent or non-volatile silicone fluid in the composition of the invention. As an alternative embodiment, the low viscosity silicone fluid in the mixture of silicone elastomer and low viscosity silicone fluid may be different from the volatile diluent or nonvolatile silicone fluid in the composition of the present invention.

Particularly preferred mixtures of silicone elastomers and low viscosity silicone fluids include mixtures of dimethicone crosspolymers as defined herein and non-volatile dimethicone or non-volatile polycyclomethicone or pentasiloxane. Particularly preferred silicone crosspolymers include dimethicone crosspolymers as defined herein, such as the Dow Corning9040 silicone elastomer blend available from Dow Corning inc.

Suitably, the mixture of silicone elastomer and low viscosity silicone fluid is also thixotropic. Suitably, the mixture of silicone elastomer and low viscosity silicone fluid exhibits a high viscosity when measured at 25 ℃. The viscosity of the silicone elastomer/low viscosity silicone fluid mixture can be measured by a rotational viscometer, such as a Brookfield Synchro-lec viscometer or a Wells-Brookfield cone/plate viscometer available from Brookfield Engineering Laboratories, Stoughton, MA, USA, using test methods ASTM D-1084 (for cup/spindle viscometer) and ASTM D-4287 (for cone/plate viscometer). Suitably, a viscometer designed for the high viscosity region (HA and HB modes) is used.

Suitably, it comprises 15% by volume of silicone elastomer and 85% by volume of silicone elastomer having a thickness of 5mm at 25 ℃ when measured by the method described above²A mixture of linear polydimethylsiloxanes having a kinematic viscosity per second (centistokes) of greater than or equal to 220,000mm, i.e.Dow Corning200 fluid 5cSt from Dow Corning²S, more preferably 240,000mm or more²S, most preferably greater than or equal to 250,000mm²And s. Preferably, whenComprising 15% by volume of a silicone elastomer and 85% by volume of a silicone elastomer having a thickness of 5mm at 25 ℃ when measured by the method described above²Mixtures of linear polydimethylsiloxanes having a dynamic viscosity per second (i.e., Dow Corning200 fluid 5cSt from Dow Corning) have a dynamic viscosity of less than or equal to 800,000mm²S, more preferably 700,000mm or less²S, most preferably less than or equal to 600,000mm²/s。

Suitably, the silicone elastomer itself is non-volatile. Suitably, the mixture of silicone elastomer and low viscosity silicone fluid is non-volatile. In other words, neither the silicone elastomer itself nor the mixture of silicone elastomer and low viscosity silicone fluid exhibits a measurable vapor pressure at ambient temperature. Preferably, the volatile content of the silicone elastomer itself and of the mixture of silicone elastomer and low-viscosity silicone fluid is less than or equal to 0.6% by weight, more preferably less than or equal to 0.4% by weight, most preferably less than or equal to 0.3% by weight, respectively, at 150 ℃, based on the total weight of the silicone elastomer itself and of the mixture of silicone elastomer and low-viscosity silicone fluid.

Suitably, when the silicone elastomer is in the form of a mixture of a silicone elastomer and a low viscosity silicone fluid, the silicone elastomer is present in an amount of less than or equal to 40% by volume of the mixture, preferably less than or equal to 30% by volume of the mixture, more preferably less than or equal to 20% by volume of the mixture. Suitably, when the silicone elastomer is in the form of a mixture of a silicone elastomer and a low viscosity silicone fluid, the silicone elastomer is present in an amount of greater than or equal to 5% by volume of the mixture, preferably greater than or equal to 10% by volume of the mixture, more preferably greater than or equal to 15% by volume of the mixture. The remaining components of the aforementioned mixture generally consist essentially of one or more of the said low viscosity silicone fluids.

Those skilled in the art will appreciate that when the silicone elastomer is in the form of a mixture of silicone elastomer and low viscosity silicone fluid, it is necessary to include an appropriate amount of this mixture so that the total silicone elastomer content of the composition of the present invention is preferably within the preferred limits set forth above. Suitably, the amount may be determined by routine experimentation based on known concentrations of silicone elastomer and low viscosity silicone fluid mixture.

Preferably, when the silicone elastomer is in the form of a mixture comprising a silicone elastomer as defined herein and a low viscosity silicone fluid, the mixture is present in an amount greater than or equal to 1% by weight, more preferably greater than or equal to 1.5% by weight, most preferably greater than or equal to 2% by weight, based on the total weight of the composition. Preferably, when the silicone elastomer is in the form of a mixture comprising a silicone elastomer as defined herein and a low viscosity silicone fluid, the mixture is present in an amount of less than or equal to 10 wt%, more preferably less than or equal to 7 wt%, most preferably less than or equal to 5 wt% of the total weight of the composition. It is particularly preferred that the composition comprises 3% by weight of the total composition of a mixture consisting of a silicone elastomer as defined herein and a low viscosity silicone fluid.

The term "volatile diluent" as used herein refers to a diluent that evaporates substantially at normal body temperature (i.e., up to and including 38 ℃) and atmospheric pressure. Preferably, the volatile diluent is substantially vaporized at room temperature (i.e., 25 ℃) and atmospheric pressure.

Suitably, the volatile diluent exhibits a significant vapour pressure at ambient temperature. Preferably the volatile diluent exhibits a heat of vaporization of greater than or equal to 50kJ/kg at 25 ℃, more preferably greater than or equal to 75kJ/kg, more preferably greater than or equal to 100kJ/kg, and most preferably greater than or equal to 125 kJ/kg. Preferably the volatile diluent exhibits a heat of vaporization of less than or equal to 275kJ/kg at 25 ℃, more preferably less than or equal to 250kJ/kg, more preferably less than or equal to 225kJ/kg, and most preferably less than or equal to 200 kJ/kg.

Suitably, the volatile diluent exhibits a low viscosity when measured at 25 ℃. The viscosity of the volatile diluent can be measured using a glass capillary viscometer, such as an Ubbelohde viscometer, available from Fisher Scientific Co., Pittsburgh, Pa., USA, using the measurement method ASTM D-445, IP 71.

The volatile diluent preferably has a thickness of greater than or equal to 0.5mm when measured as described above²Dynamic viscosity/s, more preferably greater than or equal to 2mm²S, particularly preferably greater than or equal to 3mm²And s. The volatile diluent preferably has a thickness of less than or equal to 10mm when measured as described above²Dynamic viscosity/s, more preferably less than or equal to 9mm²S, particularly preferably less than or equal to 8mm²/s。

The volatile diluent is preferably a volatile silicone fluid (e.g., a liquid) because it is generally compatible with the non-volatile silicone fluid. Suitably, the volatile silicone fluid comprises a silicone polymer, in particular a cyclomethicone silicone polymer. The volatile silicone fluid is preferably selected from the group consisting of polydimethylcyclosiloxanes, such as cyclohexasiloxane, cyclopentasiloxane, dodecamethylcyclohexasiloxane, decamethylcyclopentasiloxane, octamethylcyclotetrasiloxane; polymethyldisiloxane such as hexamethyldisiloxane; or polymethyltrisiloxane, such as octamethyltrisiloxane. Highly preferred volatile silicone fluids include polydimethylcyclosiloxanes, especially cyclopentasiloxanes and cyclohexasiloxanes, specifically dodecamethylcyclohexasiloxanes and decamethylcyclopentasiloxanes.

Examples of suitable volatile silicone fluids are Dow Corning 244, comprising polycyclomethylsiloxane octamethylcyclotetrasiloxane; dow Corning245, comprising polycyclomethylsiloxane decamethylcyclopentasiloxane; dow corning246, comprising polycyclomethicone decadimethylcyclohexasiloxane; and Dow Corning 345, comprising polycyclomethylsiloxane decamethylcyclopentasiloxane.

The volatile diluent preferably has a weight average molecular weight of greater than or equal to 150, more preferably greater than or equal to 250, and most preferably greater than or equal to 300. The volatile diluent preferably has a weight average molecular weight of 1000 or less, more preferably 800 or less, still more preferably 600 or less, and most preferably 500 or less.

Mixtures of volatile silicone fluids can also be used to alter the rate of volatilization, if desired. Volatile diluents can be added to the mixture of non-volatile silicone fluid, fumed silica and silicone elastomer in any desired proportion to reduce the viscosity of the composition of the invention to prepare an oil or grease that is easy to apply. At high dilution, for example, if 1000 parts by weight of the volatile diluent are added to 1 part by weight of the mixture of non-volatile silicone fluid, fumed silica and silicone elastomer, the product can be applied in the form of a flowing fluid with a suitable applicator, such as a roll-on applicator, or even in the form of a spray from a sprayer. At the other extreme, as little as 1 part by weight of a volatile diluent may be added to a mixture of 99 parts by weight of a nonvolatile silicone fluid, fumed silica and silicone elastomer to produce a more viscous composition for ease of application.

Suitably, the volatile diluent is present in an amount of greater than or equal to 1%, more preferably greater than or equal to 5%, still more preferably greater than or equal to 10%, still more preferably greater than or equal to 15%, still more preferably greater than or equal to 20%, most preferably greater than or equal to 25% by weight of the total composition of the present invention. Suitably, the volatile diluent is present in an amount of less than or equal to 99.9%, preferably less than or equal to 80%, preferably less than or equal to 70%, preferably less than or equal to 60%, most preferably less than or equal to 50% by weight of the total composition of the present invention.

It will be apparent that if the silicone elastomer is in the form of a mixture of silicone elastomer and volatile silicone fluid, then the total amount of volatile diluent in the composition of the invention (i.e. the sum of the volatile silicone fluid and the volatile diluent itself in the mixture of elastomer and volatile silicone fluid) is preferably within the preferred ranges set forth above.

Suitably, a volatile diluent may form the balance of the composition of the present invention.

As used herein, the term "non-volatile silicone fluid" includes silicone fluids that do not substantially evaporate from the compositions of the present invention at normal body temperature (i.e., up to and including 38℃.) and atmospheric pressure. Preferably, the non-volatile silicone fluid does not substantially evaporate from the composition at room temperature (i.e., up to and including 25 ℃) and atmospheric pressure.

Suitably, the non-volatile silicone fluid does not itself exhibit a significant vapour pressure at ambient temperature. The volatile content of the non-volatile silicone fluid itself is preferably less than or equal to 0.8 wt%, more preferably less than or equal to 0.6 wt%, even more preferably less than or equal to 0.4 wt%, and most preferably less than or equal to 0.3 wt%, based on the total weight of the non-volatile silicone fluid itself, at 150 ℃.

Suitably, the non-volatile silicone fluid component forms the basis of the composition of the present invention and provides chemical properties that act as a barrier between the damaged target tissue and the environment. Suitably, the non-volatile silicone fluid is a silicone polymer.

The non-volatile silicone fluid is preferably a non-volatile silicone oil. The non-volatile silicone fluid preferably has a thickness of greater than or equal to 500mm at 25 DEG C²Dynamic viscosity/s, more preferably greater than or equal to 5,000mm²S, most preferably greater than or equal to 10,000mm²Measured in/s using a glass capillary viscometer as described herein in ASTM D-445, IP 71. The non-volatile silicone fluid preferably has a viscosity of less than or equal to 200,000mm at 25 DEG C²Dynamic viscosity/s, more preferably less than or equal to 100,000mm²S, most preferably less than or equal to 50,000mm²And s. Suitably up to 100,000mm²Viscosity per second can be measured by a glass capillary viscometer in ASTM D-445, IP71, 100,000mm²The viscosity above/s can be measured using a rotational viscometer and test methods ASTM D-1084 and ASTM D-4287. Highly preferred nonvolatile silicone fluids have a viscosity of about 30,000mm at 25 deg.C as measured by a glass capillary viscometer in accordance with ASTM D-445, IP71²Dynamic viscosity per second.

The non-volatile silicone fluid preferably comprises a silicone polymer, particularly a linear silicone polymer, especially a linear dimethylsiloxane polymer. Suitably, the linear siloxane polymer is substantially non-crosslinked. Highly preferred non-volatile silicone fluids include polydimethylsiloxane polymers, especially linear polydimethylsiloxane polymers.

The weight average molecular weight of the nonvolatile silicone fluid is preferably greater than or equal to 1,500, more preferably greater than or equal to 2,500, and most preferably greater than or equal to 5,000. The weight average molecular weight of the nonvolatile silicone fluid is preferably less than or equal to 100,000, more preferably less than or equal to 50,000, still more preferably less than or equal to 25,000, and most preferably less than or equal to 20,000.

Conveniently, in the compositions of the present invention, the mixture of silicone elastomer and, if used, silicone elastomer with a low viscosity silicone fluid has a higher viscosity than the non-volatile silicone fluid, which has a higher viscosity than the volatile diluent.

By increasing the viscosity of the non-volatile silicone fluid in the compositions of the present invention, compositions having increased resistance and resistance to removal from the target tissue site can be prepared, particularly after evaporation of the volatile diluent from the composition. Similarly, compositions that are easier to apply and remove from target tissue can be prepared by reducing the viscosity of the non-volatile silicone fluid component. By using a full range of silicone oil viscosities, the compositions of the present invention can be tailored to the unique needs of each situation. Particularly preferably about 30,000mm at 25 deg.C²Silicone fluids of viscosity/s because they provide a balance between residual durability and ease of application. A particularly preferred non-volatile silicone fluid is Dow Corning200, manufactured by Dow-Corning Inc., having a viscosity of about 30,000mm at 25 deg.C²Linear polydimethylsiloxane polymers of viscosity/s (Midland, Michigan).

The nonvolatile silicone fluid is preferably present in an amount greater than or equal to 20 weight percent, more preferably greater than or equal to 25 weight percent, even more preferably greater than or equal to 30 weight percent, and most preferably greater than or equal to 35 weight percent, based on the total weight of the composition of the present invention. The nonvolatile silicone fluid is preferably present in an amount less than or equal to 65 weight percent, more preferably less than or equal to 60 weight percent, and even more preferably less than or equal to 55 weight percent, based on the total weight of the composition of the present invention. Particularly preferred compositions of the present invention contain from 40 to 50% by weight of the nonvolatile silicone fluid, based on the total weight of the composition.

It will be apparent that if the silicone elastomer is in the form of a mixture of silicone elastomer and nonvolatile silicone fluid, then the total amount of nonvolatile silicone fluid in the composition of the invention (i.e., the sum of the nonvolatile silicone in the mixture of silicone elastomer and nonvolatile silicone fluid and the nonvolatile silicone fluid itself) is preferably within the preferred ranges set forth above.

Suitably, the fumed silica provides a microarchitectural structure when dispersed in a non-volatile silicone fluid to provide a gel. The fumed silica is preferably amorphous. The viscosity of the non-volatile silicone fluid increases dramatically when the fluid is mixed (i.e., blended) with an appropriate amount of fumed silica to form, for example, a non-fluid greasy gel. Any amorphous fumed silica suitable for thickening the non-volatile silicone fluid component can be employed. The fumed silica includes both untreated types and types that have been chemically treated to alter the surface of the fumed silica. Examples of suitable fumed silicas include, but are not limited to, Aerosil^TM90. 130, 200, 300, 380, R202, R805, R812, R972, R974(Degussa Corporation, Ridgefield Park, New Jersey) and CAB-O-SIL^TMTS-720 and M-5(Cabot Corporation, Tuscola, Illonois). Typically, Aerosil^TM200、Aerosil^TM R974、CAB-O-SIL^TMTS-720, as well as any other common equivalents made by other fumed silica manufacturers, are preferred because they suitably thicken the nonvolatile silicone fluid. Generally, the greater the amount of fumed silica in the blend, the greater the resulting gel viscosity.

The fumed silica content is preferably greater than or equal to 0.25 weight percent, more preferably greater than or equal to 0.5 weight percent, even more preferably greater than or equal to 1 weight percent, and most preferably greater than or equal to 2 weight percent, based on the total weight of the composition of the present invention. The fumed silica content is preferably less than or equal to 10 weight percent, more preferably less than or equal to 8 weight percent, even more preferably less than or equal to 6 weight percent, and most preferably less than or equal to 5 weight percent of the total weight of the composition of the present invention. Particularly preferred compositions of the invention comprise 2.5 to 3.5% by weight, in particular 3% by weight, of fumed silica, based on the total weight of the composition.

In the compositions of the present invention, the mixture of non-volatile silicone fluid and fumed silica preferably comprises greater than or equal to 0.25 weight percent, more preferably greater than or equal to 0.5 weight percent, and most preferably greater than or equal to 1 weight percent fumed silica. In the compositions of the present invention, the mixture of non-volatile silicone fluid and fumed silica preferably comprises less than or equal to 12 weight percent, more preferably less than or equal to 9 weight percent, and most preferably less than or equal to 5 weight percent fumed silica. The compositions generally provide a balance between consistency and applicability.

In the compositions of the present invention, the mixture of non-volatile silicone fluid and fumed silica preferably comprises less than or equal to 99.75 weight percent, more preferably less than or equal to 99.5 weight percent, and most preferably less than or equal to 99 weight percent of non-volatile silicone fluid. In the compositions of the present invention, the mixture of non-volatile silicone fluid and fumed silica preferably comprises greater than or equal to 88 wt%, more preferably greater than or equal to 91 wt%, and most preferably greater than or equal to 95 wt% of the non-volatile silicone fluid.

The mixture of non-volatile silicone fluid and fumed silica is preferably present in the compositions of the invention in an amount of greater than or equal to 1 weight percent, preferably greater than or equal to 22 weight percent, preferably greater than or equal to 24.9 weight percent, preferably greater than or equal to 47 weight percent, preferably greater than or equal to 49.9 weight percent, preferably greater than or equal to 57 weight percent, preferably greater than or equal to 59.9 weight percent, preferably greater than or equal to 62 weight percent, preferably greater than or equal to 64.9 weight percent, based on the total weight of the composition. The amount of the mixture of non-volatile silicone fluid and fumed silica in the compositions of the invention is preferably less than or equal to 98.9, preferably less than or equal to 96, preferably less than or equal to 94.9, preferably less than or equal to 92, preferably less than or equal to 89.9, preferably less than or equal to 87, preferably less than or equal to 84.9, preferably less than or equal to 82, preferably less than or equal to 79.9, preferably less than or equal to 77, preferably less than or equal to 74.9, preferably less than or equal to 72 weight percent of the total weight of the composition.

The compositions of the present invention preferably comprise 1-50 parts by weight of a silicone elastomer, 1-100 parts by weight of fumed silica, 400-600 parts by weight of a volatile diluent, and 400-600 parts by weight of a non-volatile silicone fluid. More preferably, the compositions of the present invention comprise 1 to 20 parts by weight of the silicone elastomer, 10 to 50 parts by weight of the fumed silica, 400-600 parts by weight of the volatile diluent, and 400-600 parts by weight of the nonvolatile silicone fluid.

Suitably, the compositions of the present invention have a lower viscosity than a comparative composition which does not comprise a volatile diluent, i.e. a composition comprising a non-volatile silicone fluid, a fumed silica and a mixture of silicone elastomers. As a result, the compositions of the present invention can be made in the form of an easily spreadable ointment, gel, oil or thin grease which can be applied to the wound without further damage or discomfort. Suitably, after the composition of the invention has been applied to a wound, the volatile diluent evaporates therefrom, and the resulting composition generally has a relatively high viscosity which is substantially equivalent to that of a composition comprising only a mixture of the non-volatile silicone fluid, the silicone elastomer and the fumed silica. In other words, a coating having the viscosity of a thick ointment, grease or film may be formed from the spreadable ointment, thereby providing greater wound adherence and stain resistance during application without causing further injury or excessive pain and discomfort to the wound.

It will be apparent to those skilled in the art that the consistency of the compositions of the present invention can be adjusted by varying the amounts of volatile diluents, silicone elastomers, non-volatile silicone fluids and fumed silica. As a result, the compositions of the present invention may be formed into films or coatings, and in the form of spreadable ointments, gels, oils, or thin greases. Generally, the physical and chemical properties of the remaining non-volatile silicone fluid, silicone elastomer and fumed silica mixture do not change upon evaporation of the volatile diluent. However, it is clear that, particularly for mixtures of high viscosity silicone fluids, silicone elastomers and fumed silicas, trace amounts of volatile diluents remain in the composition after application and are eventually driven off by body temperature.

The compositions of the invention are preferably in the form of gels or ointments. Generally, this provides a balance between the after-durability and ease of application of the final composition after evaporation of the volatile diluent.

The compositions of the present invention (e.g., fumed silica, non-volatile silicone fluid, volatile diluent, and silicone elastomer) preferably have a particle size of greater than or equal to 1,000mm when measured at 25 ℃ using a glass capillary viscometer using test method ASTM D-445, IP71²A dynamic viscosity in s of preferably 5,000mm or more²S, more preferably greater than or equal to 10,000mm²And s. The compositions of the present invention preferably have a viscosity of less than or equal to 25,000mm when measured at 25 ℃ using a glass capillary viscometer with test method ASTM D-445, IP71²Dynamic viscosity/s, more preferably 22,000mm or less²S, most preferably less than or equal to 20,000mm²/s。

The resulting composition after evaporation of the volatile diluent from the composition of the present invention (i.e., after coating) preferably has a thickness of greater than or equal to 27,000mm when measured at 25 ℃ using a glass capillary viscometer using test method ASTM D-445, IP71²Dynamic viscosity/s, more preferably greater than or equal to 30,000mm²And s. When using a glass capillary viscometer, toTest methods ASTM D-445, IP71 the resulting compositions of the invention preferably have a thickness of 45,000mm or less after evaporation of the volatile diluent when measured at 25 deg.C²Dynamic viscosity/s, more preferably 40,000mm or less²S, most preferably 35,000mm or less²/s。

Conveniently, a composition of the invention having a particular initial viscosity within the aforementioned limits (e.g., fumed silica, non-volatile silicone fluid, volatile diluent, and silicone elastomer) will generally reach the desired final viscosity within the aforementioned limits (i.e., after evaporation of the volatile diluent therefrom) more quickly than a comparative composition having the same particular initial viscosity that does not include the silicone elastomer.

Suitably, the volatile diluent is evaporated from the composition of the invention after it has been applied to the target tissue site (i.e. when the composition is subjected to a temperature of about 38 ℃), in the form of a gel/ointment having a viscosity of 15,000 mm and 20,000mm at 25 ℃²The composition of the invention having an initial dynamic viscosity (ASTM D-445, IP71) of 30,000-35,000mm at 25 ℃ was formed²The resulting composition has a dynamic viscosity per second (ASTM D-445, IP71) of less than or equal to 10 minutes, more preferably less than or equal to 8 minutes, still more preferably less than or equal to 6 minutes, still more preferably less than or equal to 4 minutes, and most preferably less than or equal to 3 minutes.

Highly preferred compositions of the invention comprise:

1-5 wt% fumed silica as defined herein;

35-65% by weight of a non-volatile silicone fluid as defined herein;

25-65 wt% of a volatile diluent as defined herein;

1-5% by weight of a mixture of silicone elastomer and low viscosity silicone fluid as defined herein, wherein the component parts of the composition total 100% by weight.

More highly preferred compositions of the present invention consist essentially of:

1-5 wt% fumed silica as defined herein;

35-65% by weight of a non-volatile silicone fluid as defined herein;

25-65 wt% of a volatile diluent as defined herein;

1-5% by weight of a mixture of a silicone elastomer and a low viscosity silicone fluid as defined herein; and

0-30 wt% of a pharmaceutically active agent as defined herein.

According to a preferred embodiment of the invention, the composition comprises one or more pharmaceutically active agents.

As used herein, the term "pharmaceutically active agent" includes any compound, including pharmaceutically acceptable drug derivatives, such as salts, solvates, and prodrugs, and any composition useful for the curative and/or prophylactic treatment of a condition in a human or animal.

The pharmaceutically active agent preferably has antibacterial, anti-inflammatory, antiviral and/or antifungal activity. Substantially preferred pharmaceutically active agents comprise antibacterial agents. Alternatively it is particularly preferred that the pharmaceutically active agent comprises an anti-inflammatory agent.

The pharmaceutically active agent is preferably present in an amount of less than or equal to 50%, more preferably less than or equal to 30%, more preferably less than or equal to 10%, and most preferably less than or equal to 3% by weight of the total composition of the present invention. The content of pharmaceutically active agent is preferably greater than or equal to 0.1%, more preferably greater than or equal to 0.5%, and particularly preferably greater than or equal to 1.0% by weight of the total composition of the invention.

Suitably, the pharmaceutically active agent may be in liquid, gel or powder form. The pharmaceutically active agent is preferably in powder form, in particular a powder that is insoluble in typical pharmaceutically acceptable diluents, such as water or ethanol insoluble powders.

Preferred antimicrobial agents include antibacterial zeolites, chlorhexidine, polymyxin sulfate B, benzachromiumchloride, bimatocin (Benzamycin), clindamycin, erythromycin, tetracycline, mupirocin, bacitracin zinc, and neomycin sulfate. Particularly preferred antimicrobial agents include antimicrobial zeolites.

Preferred antibacterial zeolites include zeolites in which the ion-exchangeable ions of the zeolite, such as sodium, potassium, calcium, magnesium and iron ions, have been partially or fully ion-exchanged with antibacterial ions. Examples of suitable antimicrobial ions include silver, copper, zinc, mercury, tin, lead, bismuth, cadmium, chromium, and thallium ions. Preferred antimicrobial metal ions are silver, copper and zinc ions. These ions may be used alone or in combination. A particularly preferred antimicrobial ion is silver.

Zeolites, whether natural or synthetic, may be used as the "zeolite component". Examples of such zeolites are disclosed in U.S. Pat. No. 5,556,699, which is incorporated herein by reference. The method of making the antimicrobial zeolites for use in the compositions of the present invention can be prepared by techniques well known to those skilled in the art, such as the techniques disclosed in U.S. Pat. No. 5,556,699.

The antimicrobial metal ion content of the zeolite is preferably greater than or equal to 0.1%, preferably greater than or equal to 0.25%, more preferably greater than or equal to 0.75%, and most preferably greater than or equal to 1% by weight of the zeolite. The antimicrobial metal ion content of the zeolite is preferably less than or equal to 15%, more preferably less than or equal to 10%, and most preferably less than or equal to 5% by weight of the zeolite. The term "% by weight of zeolite" as used herein refers to the weight% of zeolite weighed after drying at a temperature of 110 ℃.

It will appear to those skilled in the art that while antibacterial zeolites have suitable antibacterial activity, they generally require complex formulations suitable for topical application to the target tissue. Surprisingly, it has been found that antibacterial zeolites can be incorporated into the compositions of the present invention without the need for more complex processing techniques. Furthermore, the resulting compositions of the present invention including the antibacterial zeolite may exhibit higher antibacterial activity than the antibacterial zeolite alone.

Preferred anti-inflammatory agents include non-steroidal anti-inflammatory drugs (NSAIDs). Preferred NSAIDs include phenylpropionic acids such as ibuprofen, naproxen, ketoprofen and flurbiprofen. Another preferred NSAID is acetylsalicylic acid. Highly preferred NSAIDs include ibuprofen and acetylsalicylic acid, especially acetylsalicylic acid.

Suitably, the compositions of the present invention may comprise one or more pharmaceutically acceptable adjuvants. In particular, the compositions of the present invention may include an antioxidant. When present, the antioxidant is present in an amount less than or equal to 15 weight percent, more preferably less than or equal to 10 weight percent, based on the total weight of the composition of the present invention. The antioxidant content is preferably greater than or equal to 1% by weight, more preferably greater than or equal to 3% by weight, relative to the total weight of the composition of the invention.

Preferred antioxidants include alpha-tocopherol, gamma-tocopherol, delta-tocopherol, natural source extracts rich in tocopherol, L-ascorbic acid and its sodium or calcium salts, palmityl-DL-ascorbic acid, propyl gallate, octyl gallate, dodecyl gallate, Butyl Hydroxyanisole (BHA) gallate and Butyl Hydroxytoluene (BHT) gallate. A highly preferred antioxidant is alpha-biological phenol (vitamin E).

According to another aspect, the present invention provides a method of delivering a pharmaceutically active agent as defined above to a target tissue by applying a composition of the invention comprising the pharmaceutically active agent to the target tissue.

Suitably, the composition of the invention as defined herein is suitable for use in medicine, in particular for reducing and/or preventing scarring by applying the composition to a wound, incision and/or skin lesion. Conveniently, the compositions of the present invention may be administered locally to the target tissue site.

Conveniently, when applied, the compositions of the present invention improve or reduce existing scarring.

According to another aspect, the present invention provides a method of reducing and/or preventing scarring, in particular an overgrowth or keloid scar, comprising applying a composition of the invention as defined herein to a wound, incision and/or skin lesion. Similarly, the present invention provides a wound dressing comprising a composition of the invention as defined herein. Suitably, the wound dressing may be in the form described herein, for example a gel, thickened ointment, film or the like.

According to another aspect, the present invention provides a method of preparing a composition of the invention as defined herein, comprising contacting, preferably mixing, a non-volatile silicone fluid and fumed silica, a volatile diluent and a silicone elastomer (and a pharmaceutically active agent, if present). The volatile diluent and silicone elastomer (and pharmaceutically active agent, if present) are preferably added to the mixture of non-volatile silicone fluid and fumed silica.

The compositions of the present invention are preferably prepared by methods well known to those skilled in the art, for example, by using a blender, pulverizer, etc., and other methods suitable for mixing silicone oils with fumed silica. In addition, pressure vessels and condensing systems may be used to maintain the volatile diluent in the compositions of the present invention. Suitably, a mixture of the non-volatile silicone fluid and the fumed silica is first prepared and then mixed with the volatile diluent and the silicone elastomer. Alternatively, the mixture of non-volatile silicone fluid, fumed silica, and volatile diluent can be formed in one step, and the silicone elastomer added. It will be apparent to those skilled in the art that when a pharmaceutically active ingredient is present, it may be added at any step in the preparation of the compositions of the present invention.

Generally, when the compositions of the present invention include a pharmaceutically active agent or pharmaceutically acceptable adjuvant, a masterbatch comprising the pharmaceutically active agent or adjuvant in admixture with a non-volatile silicone fluid, fumed silica, silicone elastomer and volatile diluent is first prepared. Suitably, the masterbatch comprises 20% by weight of the masterbatch of a pharmaceutically active agent and/or adjuvant. The masterbatch is then diluted with a blend of non-volatile silicone fluid, fumed silica, volatile diluent and silicone elastomer to form the composition of the invention having the necessary concentration of the pharmaceutically active agent and/or adjuvant described herein (typically 1-5% by weight of the composition for the antibacterial zeolite). Advantageously, this processing technique ensures proper dispersion of the pharmaceutically active agent in the compositions of the present invention while minimizing agglomeration of the pharmaceutically active agent, thereby resulting in higher activity of the pharmaceutically active agent in the compositions of the present invention.

Alternatively, or additionally, dispersing agents such as magnesium stearate may be added to the masterbatch to facilitate dispersion of the pharmaceutically active agent in the composition of the invention. Typically, the anhydrous dispersion is mixed with the anhydrous pharmaceutically active agent prior to mixing. Preferably, 10% by weight of a dispersant is included. The pharmaceutically active agent/dispersant mixture may then be used to form a masterbatch as described herein. Preferably, particularly when an antibacterial zeolite is used, the compositions of the present invention are prepared under anhydrous conditions, since the inclusion of water in the compositions of the present invention promotes discolouration and aggregation of the pharmaceutically active agent, thereby reducing the efficacy of the composition.

It will be apparent to those skilled in the art that the compositions of the present invention may be administered by non-medical professionals. Suitably, the compositions of the present invention are applied to the target tissue by means well known to those skilled in the art, for example by means of a spatula, roll-on or spray-on applicator.

According to another aspect, the present invention provides a method of treating a wound comprising applying a composition of the present invention to the wound.

According to another aspect, the present invention provides a topical drug delivery system comprising a composition of the present invention and a pharmaceutically active agent.

According to another aspect, the present invention provides a wound dressing comprising a composition of the present invention. It is apparent that the wound dressing may be considered a self-drying wound dressing because only body heat is required to effectively evaporate the volatile diluent after application to the target tissue site.

According to another aspect, the present invention provides the use of a silicone elastomer for the manufacture of a wound dressing, in particular a wound dressing which self dries after application to a target tissue site of the body.

The invention will now be described by way of the following non-limiting examples.

The following raw materials were used:

dow Corning200, having a thickness of about 30,000mm at 25 deg.C²Viscosity per second (non-volatile silicone fluid);

fumed silica-Aerosil 200;

dow Corning245, comprising decamethylpentasiloxane, having a thickness of 4mm at 25 ℃²Viscosity per second (volatile diluent);

dow Corning246, comprising dodecamethylcyclohexasiloxane, having a thickness of 7.7mm at 25 ℃²Viscosity per second (volatile diluent);

dow Corning9040 silicone elastomer blends comprising dimethicone crosspolymer in polycyclomethicone and having a viscosity of 250,000-580,000mm at 25 ℃²Viscosity per second;

dow Corning9041 silicone elastomer blends comprising dimethicone crosspolymer in dimethicone fluid and having a viscosity of 300,000-500,000mm at 25 ℃²Viscosity per second;

Agion^TMantimicrobial zeolites, wherein the ion-exchangeable ions of the zeolite have been partially or fully exchanged with silver ions, are supplied by Agion Technologies, 60 Audubon Road, Wakefield, MA 01880, USA.

Example 1 preparation of the composition of the invention

A mixture comprising 45% by weight Dow Corning245, 50% by weight Dow Corning200, 3% by weight fumed silica (Aerosil 200) and 2% by weight Dow Corning9040 silicone elastomer blend was heated at ambient temperature withThe JH Day Pony mixer was stirred under anhydrous conditions for 2 hours. The resulting product contained a viscosity of 19,000-21,000mm at 25 ℃ when measured with a glass capillary viscometer in ASTM D-445, IP71²Gels in/s.

EXAMPLE 2 preparation of comparative composition

A mixture comprising 45 wt% Dow Corning245, 52 wt% Dow Corning200 and 3 wt% fumed silica (Aerosil 200) was stirred at ambient temperature with a JH Day Pony mixer under anhydrous conditions for 2 hours. The resulting product has a viscosity of 18,000-20,000mm at 25 ℃ when measured with a glass capillary viscometer in ASTM D-445, IP71²Gels in/s.

Example 3 drying time for examples 1 and 2

Ten different human subjects were selected. A sufficient amount of the composition of example 1 to cover a 2 inch area and the composition of example 2 applied in the same size area were applied to each subject's two forearms. Each subject was asked to monitor the sensory hardening and adherence of each composition to the skin, and the time when hardening and adherence no longer increased (referred to as the end time) (e.g., the effective time when substantially all of the volatile diluent evaporated from the composition) was recorded. The results for each composition were averaged (mean end time) for ten subjects and are listed in table 1.

TABLE 1

	Average end time
		Example 1	4.4 minutes
Example 2	15.2 minutes

The results show that the example 1 composition containing the silicone elastomer dried much faster than the comparative composition without the silicone elastomer (example 2) when both compositions were applied to the target tissue site of the body.

EXAMPLE 4 preparation of compositions of the invention incorporating an antimicrobial agent

By mixing Agion^TMThe powder was added to a mixture of a non-volatile silicone fluid, fumed silica, volatile silicone diluent, and silicone elastomer to produce a composition containing 20 wt% Agion^TMAnd the remainder of the masterbatch (80 wt%) comprises a mixture of Aerosil 200, Dow Corning245 and Dow Corning9040 silicone elastomers (3 wt% Aerosil 200: 50 wt% Dow Corning 200: 45 wt% Dow Corning 245: 2 wt% Dow Corning 9040). Stirring the masterbatch with a JH DayPony stirrer at ambient temperature under anhydrous conditions for 2 hours to achieve Agion^TMAnd (4) dispersing the powder. The masterbatch was then diluted with the requisite amount of a mixture of Aerosil 200, Dow Corning245 and Dow Corning9040 (3 wt%: 50 wt%: 45 wt%: 2 wt%, (Aerosil: Dow Corning 200: Dow Corning 245: Dow Corning 9040)) to form a viscosity of 19,000-²The following gel forms of the compositions according to the invention.

	AgionTM(in% by weight of the composition)	Aerosil: Dow Corning 200: Dow Corning 245: Dow Corning9040 (3: 50: 45: 2) in composition weight%
			Example 4a	1	99
Example 4b	2	98
			Example 4c	5	95

Example 5 wound healing/antibacterial Activity in vivo

Three volunteers with wounds that started to develop into keloid scars were selected.

The composition of example 4a (2g) was applied to the scar of the first volunteer to attach the composition to the tissue site.

A control composition (2g) comprising a mixture of 3 wt% Aerosil 200, 50 wt% Dow Corning200, 45 wt% Dow Corning245 and 2 wt% Dow Corning9040 was applied to the scar of the second volunteer to attach the resulting composition to the tissue site.

Separate Agion^TMPowder (40mg) was placed on the scar of the third volunteer and the powder was fixed to the tissue site with clear adhesive gauze.

Each patient was monitored over a month period and a reduction in redness (representing a reduction in infection) and a flattening of the scar (representing an improvement and/or prevention and/or reduction in scar) were recorded. The results are shown in Table 2 below.

TABLE 2

Sample (I)	Reduction of redness symptoms	Scar flattening
			Example 4a	The redness is immediately reduced after 1-2 days, and the occurrence of redness is further reduced	Scar levels steadily decrease. There was visible signs of scar regression after one month.
Control	The redness was slightly reduced after one month	Scar levels were reduced after one month, but were not as evident after one month as example 4a, and there was no evidence of scar regression.
			Agion aloneTM	After 4 days, a reduction in redness was observed	Scar aggravation

The results show that the composition of the present invention including an antibacterial agent not only reduces redness symptoms (indicator of antibacterial activity) of scars, but also prevents and/or improves scarring. In addition, the combination of the antimicrobial zeolite and the composition of the present invention also provides a synergistic effect of antimicrobial and/or scar reduction effects.

Example 6

The following compositions listed in Table 3 were prepared according to the above example 4 except that Agion^TMThe antibacterial zeolite is substituted with a suitable pharmaceutically active agent.

TABLE 3

	Pharmaceutically active agent (in% by weight of the composition)	Aerosil 200: Dow Corning 245: Dow Corning9040 (3: 50: 45: 2) (composition weight%)
			Example 6a	Dichlorobiguanide hexane acetate (2% by weight)	98% by weight
Example 6b	Bimassen (3 wt%)	97% by weight
			Example 6c	Erythromycin (3 wt%)	97% by weight
Example 6d	Acetylsalicylic acid (5 wt%)	95% by weight
			Example 6e	Vitamin E (4% by weight)	96% by weight
Example 6f	Ibuprofen (20 wt%)	80% by weight

Example 7

The following compositions listed in Table 4 were prepared according to example 1 above.

TABLE 4

	Aerosil weight%	Dow Corning245 wt%	Dow Corning246 wt%	Dow Corning 200% by weight	Dow Corning 9040% by weight	DowCorning 9041% by weight
							Example 7a	1	50	-	45	4	-
Example 7b	4	40	-	50	1	-
							Example 7c	6	45	-	45	4	-
Example 7d	6	-	45	45	4	-
							Example 7e	3	48	-	45	-	4

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where certain features and/or steps are incompatible with each other.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the above-described embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this invention (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims (35)

1. A wound dressing comprising a composition comprising 20 to 65% by weight of a non-volatile silicone fluid in admixture with 0.25 to 10% by weight fumed silica, 0.1 to 10% by weight silicone elastomer and greater than or equal to 1% by weight volatile diluent.

2. The wound dressing of claim 1, wherein the silicone elastomer comprises a silicone crosspolymer.

3. The wound dressing of claim 2, wherein the silicone crosspolymer comprises a dimethylsiloxane crosspolymer.

4. The wound dressing of claim 1, wherein the silicone elastomer is in the form of a mixture comprising the silicone elastomer in a low viscosity silicone fluid.

5. The wound dressing of claim 4, wherein the low viscosity silicone fluid comprises linear polydimethylsiloxane or polycyclomethicone.

6. The wound dressing of claim 4, wherein the mixture of silicone elastomer and low viscosity silicone fluid has a thickness of greater than or equal to 220,000mm when measured at 25 ℃²Viscosity in/s.

7. The wound dressing of claim 4, wherein the mixture of silicone elastomer and low viscosity silicone fluid has a thickness of less than or equal to 800,000mm when measured at 25 ℃²Viscosity in/s.

8. The wound dressing of claim 4, wherein the mixture of silicone elastomer and low viscosity silicone fluid is present in an amount greater than or equal to 1% by weight of the composition.

9. The wound dressing of claim 4, wherein the mixture of silicone elastomer and low viscosity silicone fluid is present in an amount less than or equal to 10% by weight of the composition.

10. The wound dressing of claim 1, wherein 15 volume percent of the silicone elastomer and 85 volume percent of the silicone elastomer have a thickness of 5mm at 25 ℃ when measured according to ASTM D-1084²A mixture of linear polydimethylsiloxanes having a viscosity of greater than or equal to 220,000mm²Dynamic viscosity in/s.

11. The wound dressing of claim 1, wherein 15 volume percent of the silicone elastomer and 85 volume percent of the silicone elastomer have a thickness of 5mm at 25 ℃ when measured according to ASTM D-1084²A mixture of linear polydimethylsiloxanes having a viscosity of less than or equal to 800,000mm²Dynamic viscosity in/s.

12. The wound dressing of claim 1, wherein fumed silica is present in an amount greater than or equal to 1% by weight of the composition.

13. The wound dressing of claim 1, wherein the volatile diluent is present in an amount greater than or equal to 25% by weight of the composition.

14. The wound dressing of claim 1, wherein the volatile diluent comprises a volatile silicone fluid.

15. The wound dressing of claim 14, wherein the volatile silicone fluid comprises a silicone polymer.

16. The wound dressing of claim 15, wherein the silicone polymer is polycyclomethicone.

17. The wound dressing of claim 1, wherein the non-volatile silicone fluid has a thickness of less than or equal to 200,000mm when measured at 25 ℃²Dynamic viscosity in/s.

18. The wound dressing of claim 1, wherein the non-volatile silicone fluid comprises a silicone polymer.

19. The wound dressing of claim 18, wherein the silicone polymer is a linear polydimethylsiloxane.

20. The wound dressing of claim 1, wherein the non-volatile silicone fluid is present in an amount greater than or equal to 20% by weight of the composition.

21. The wound dressing of claim 1, comprising

1-5 wt% fumed silica;

35-65% by weight of a non-volatile silicone fluid;

25-60% by weight of a volatile diluent; and

1-5% by weight of a mixture of a silicone elastomer and a low viscosity silicone fluid;

wherein the sum of the parts of the components of the composition is 100% by weight.

22. The wound dressing of claim 1, wherein the composition is in the form of a spreadable ointment, gel, thin grease, or a flowing fluid spray.

23. The wound dressing of claim 1, further comprising a pharmaceutically active agent.

24. The wound dressing of claim 23, wherein the pharmaceutically active agent has antibacterial, anti-inflammatory, antiviral, and/or antifungal activity.

25. The wound dressing of claim 23, wherein the pharmaceutically active agent is selected from the group consisting of antibacterial zeolite, chlorhexidine, polymyxin B sulfate, clindamycin, erythromycin, tetracycline, mupirocin, bacitracin zinc, neomycin sulfate, ibuprofen, naproxen, ketoprofen, flurbiprofen, and acetylsalicylic acid, or combinations thereof.

26. The wound dressing of claim 23, wherein the pharmaceutically active agent is selected from the group consisting of an antibacterial agent and an NSAID.

27. The wound dressing of claim 26, wherein the antimicrobial agent is an antimicrobial zeolite.

28. The wound dressing of claim 26, wherein the NSAID is acetylsalicylic acid.

29. The wound dressing of claim 1, wherein the composition further comprises an antioxidant.

30. A method of making the wound dressing of claim 1, comprising contacting a non-volatile silicone fluid with fumed silica, a volatile diluent, and a silicone elastomer.

31. Use of the wound dressing of claim 1 in the manufacture of a medicament for the prophylactic and/or curative treatment of a wound, incision or skin lesion.

32. A topical drug delivery system comprising the wound dressing of any one of claims 23-29.

33. Use of a silicone elastomer to promote evaporation of a volatile diluent from the wound dressing of claim 1.

34. An applicator comprising a reservoir containing the wound dressing of claim 1, and a dispenser in fluid communication with the reservoir for dispensing the composition from the reservoir.

35. The applicator of claim 34, wherein said dispenser comprises a sprayer, a roller, or an applicator nozzle.