TREATMENT DEVICE FOR WOUND THERAPY The present invention relates to devices for the treatment of wounds by the application thereto of therapeutic aerosols It is known to provide wound therapeutic substances, such as disinfectants, in aerosol containers. The aerosol format provides a quick, easy and hygienic way to apply the therapeutic substances over the whole surface of a wound.

US-A-5618515 describes an aerosol spray composition for the treatment of dermal bums by cooling and anaesthetising the wound. US-A-6372196 describes hemostatically active aerosol compositions comprising polyanhydroglucuronic acids.

The present invention provides a wound treatment device comprising a housing having a first opening and a second opening, wherein the device further comprises an adhesive- coated flange around the first opening for attachment of the device around a wound to be treated, and wherein the second opening is adapted for attachment to an aerosol container.

In use, the adhesive-coated flange is applied to the skin of a patient around the wound to be treated, whereby the housing then defines an enclosed treatment volume over the wound into which a therapeutic aerosol can be sprayed through the second opening.

The housing suitably comprises sheet material. The sheet material is preferably substantially continuous and also microorganism-impermeable. Suitable continuous sheet materials may be semipermeable to allow some passage of oxygen and water vapor to and from the wound under treatment. The sheet thickness is suitably in the range of about 10 to about 1000 micrometers, preferably about 100 to about 500 micrometers. Suitable polymers for forming the housing sheet include polyolefins, polyesters, polyurethanes and poly alkoxyalkyl acrylates. The housing may be somewhat flexible, but preferably the walls of the housing are sufficiently stiff to stand up under gravity and moderate pressure, such as that applied by a secondary dressing.

The housing normally encloses a substantial volume of air or other gases above the surface being treated. The aerosol can circulate in this volume so as to achieve uniform distribution over the surface being treated. In certain embodiments, the housing may also be collapsible to a minimal volume for storage and transportation.

The second opening is adapted for attachment to a nozzle of an aerosol container. In the present specification, the term aerosol container refers to a pressurized container having stored therein a propellant and a solid or liquid therapeutic agent, and having a nozzle assembly adapted to produce an aerosol or fine spray of the therapeutic agent in the propellant gas. In certain embodiments, the device further comprises an aerosol container having an outlet nozzle operatively attached to the second opening. The aerosol canister may be demountable from the second opening, so that it may be used with one or more further devices according to the invention and/or multiple different aerosols may be used with the same device to treat the same wound with different therapeutic agents. The aerosol canister may be adapted to provide a plurality of metered doses of the therapeutic substance.

The second opening may for example comprise snap-fitting projections, or a screw thread, or a bayonet fitting, or an interference fitting for removably attaching the aerosol canister.

The second opening may comprise a closure to seal the opening, for example when the aerosol is not attached thereto. The closure could for example comprise a valve or a clip.

This enables the housing attached around the wound to form a sealed enclosure. The volume of the sealed enclosure when the device is attached to a flat surface by the flange is suitably from about lOcm3 to about 5000cm3, for example from about lOOcm3 to about 2000cm3, typically about 250cm3 to about 1000cm3. Suitably, the maximum height of the housing when the device is attached to a flat surface by the flange is from about 2cm to about 20cm, for example about 4cm to about 15cm, typically about 5cm to about 10cm.

Preferably the ratio of maximum height to maximum width of the housing when the device is attached to a flat surface by the flange is from about 1: 5 to 5: 1, suitably from about 1: 3 to 3 : or example from about 1: 2 to 2: 1. These dimensions allow free circulation and uniform distribution of the aerosol within the housing.

The aerosol canister contains a wound healing therapeutic agent, for example selected from the group consisting of antimicrobial agents, hemostatic agents, analgesic agents, growth factors, enzyme inhibitors, pain relieving agents, and mixtures thereof. The therapeutic agent is usually in the form of lyophilized particles, but it may be a liquid, or it may be dissolved or dispersed in a liquid vehicle.

The antimicrobial agent may be selected from the group consisting of antiseptics and antibiotics and mixtures thereof. Suitable antibiotics include peptide antimicrobials (e. g. defensins, Magainin, synthetic derivatives of them) tetracycline, penicillins, terramycins, erythromycin, bacitracin, neomycin, polymycin B, mupirocin, clindamycin and mixtures thereof. Suitable antiseptics include silver sulfadiazine, chlorhexidine and its salts, povidone iodine, triclosan, other silver salts and colloidal silver, sucralfate, quaternary ammonium salts and mixtures thereof.

The pain relieving agent may be selected from the group consisting of an anaesthetic, an analgesic, an antiinflammatory or mixtures thereof. Suitable anaesthetics include lidocaine or novocaine. Suitable analgesics include non-steroidal anti-inflammatory drugs (NSAIDs). Suitable antiinflammatory agents include steroids such as prostaglandins.

The growth factor may be selected from the group consisting of platelet derived growth factor (PDGF), fibroblast growth factor (FGF), transforming growth factor beta (TGF-ß), epidermal growth factor (EGF), vascular endothelial growth factor (VEGF) and insulin- like growth factor (IGF), and mixtures thereof.

The enzyme inhibitor may be selected from the group consisting of Tissue Inhibitor of Metalloproteinase (TIMP), 4- (2-aminoethyl) benzenesulfonyl fluoride (AEBSF), antithrombin, (p-Amidinophenyl) methanesulfonyl fluoride (APMSF), Aprotinin, diisopropylfluorophosphate (DFP), phenyl methyl sulfonyl fluoride (PMSF), Antipain, Chymostatin, Leupeptin, Tosyl-lysine chloromethylketone (TLCK), Tosyl-phenyl chloromethylketone (TPCK), L-trans-epoxysuccinylleucylamido (4-guanidino) butane E- 64, Amastatin, Bestatin, Diprotin, Ethylenediamine tetra-acetic acid (EDTA), pepstatin and mixtures thereof. Kallikrein inhibitors may be selected from the group consisting of

aprotonin, kallistatin, nafamostat mesilate, protease inhibitor-6 (as described in US-A- 6472143), and mixtures thereof.

The hemostatic agent may for example be selected from the group consisting of thrombin, collagen, and hemostatic polysaccharides such as alginate.

Suitable freeze-dried particulate aerosols include powdered, freeze-dried sponges of collagen with polysaccharides, including collagen-alginate for example the product available under the registered trade mark FIBRACOL from Johnson & Johnson Medical Ltd, and collagen-oxidized regenerated cellulose as described in W098/00180 and available under the registered trade mark PROMOGRAN from Johnson & Johnson Medical Ltd.

Suitably, the area of the first opening is from about 4cm2 to about 200cm, for example from about 10cm2 to about 100cm2. Suitably, the flange is from about 5mm to about 50mm wide, for example from about 10mm to about 25mm wide.

The flange is coated with a medically acceptable adhesive to permit attachment to the skin of a patient around the wound to be treated. Suitable adhesives include pressure-sensitive adhesive layers of the type conventionally used for island-type wound dressings, for example, pressure sensitive adhesives based on acrylate ester copolymers, polyvinyl ethyl ether and polyurethane as described for example in GB-A-1280631. The basis weight of the adhesive layer is preferably 20 to 250 g/m2, and more preferably 50 to 150 g/m2.

Polyurethane-based pressure sensitive adhesives are preferred. The adhesive layer is normally protected before use by one or more peel-off cover sheets, for example a release- coated sheet or a fluoropolymer cover sheet.

The wound treatment device according to the present invention may be sterile and packaged in a microorganism-impermeable container.

The device according to the present invention allows delivery of therapeutics directly, and only to, the skin condition or wound being treated. The delivery of the therapeutic directly, and only to, the wound prevents delivery of the therapeutic to intact, healthy tissue. This

technology allows accurate delivery of therapeutics based upon surface area of the skin condition.

In the case of a lyophilised therapeutic used in combination with the device according to the present invention, the delivery of the therapeutic can be in a reduced dose as there are no dissociation complications with a delivery vehicle. Furthermore, there are no safety considerations required with respect to the constituents of the delivery vehicle. A non- toxic, safe, accurate, wound size-dependent, dose is delivered directly to the skin condition. This could not be achieved without the device of the invention.

The occlusive characteristic of the device according to the present invention promotes and maintains a moist environment. This technology can be used in conjunction with existing wound management dressings and devices.

The device of the present invention can be used to deliver solutions of, suspensions of or lyophilised therapeutics directly to skin conditions including, but not limited to, diabetic foot ulcers, venous leg ulcers, pressure ulcers, surgical wounds, acute wounds, psoriasis, blistering conditions, and skin infections.

Specific embodiments of the device according to the present invention will now be described further, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows a schematic perspective view of a first device according to the present invention when applied to a wound; and Figure 2 shows a schematic perspective view of a second device according to the present invention when applied to a wound.

Referring to Fig. 1, the device 1 comprises a rigid conical housing 2 of transparent plastic sheet, for example polyethylene terephthalate. A first opening in the housing 2 is surrounded by flange 3 of width about 5mm that is formed integrally with the housing 2.

The flange 3 is adhered to the skin 4 of a patient around a wound 5 in substantially air-and liquid-tight fashion by means of a medically acceptable pressure-sensitive adhesive. A second opening 6 is provided in the housing 2 for insertion of aerosol canister 7 containing

a lyophilized therapeutic agent and a propellant. The canister 7 can readily be removed from the second opening 6, for replacement or use on another device.

Referring to Fig. 2, the device 10 is similar to that of Fig. 1 except that the housing 11 is now formed from a tubular sheet of polyethylene film. A rigid flange 12 and rigid collar 13 are provided to define the first and second openings in the housing 11. The tubular sheet housing 11 is collapsible to a substantially flat shape. This is convenient for storage and shipping.

The above embodiments have been described by way of example only. Many other embodiments falling within the scope of the accompanying claims will be apparent to the skilled reader.