Medicating Impressed Film Wound Dressing

Preferred embodiments of dressings of the invention will now be described by way of example only and with reference to the drawings in which

FIG. 1 shows a dressing comprising a continuous film containing depressions within a boarder of flat film.

FIG. 2 shows a cross-section through the dressing of FIG. 1.

FIG. 3 shows a dressing comprising a film containing square pyramidal depressions which are apertured.

FIG. 4 shows a cross-section through a portion of the dressing of FIG. 3.

FIG. 5 shows a dressing comprising a film containing conical depressions the inner rows which are apertured and the outer rows which are continuous.

FIG. 6 shows a cross-section through the dressing of FIG. 5.

FIGS. 7 and 9 show a dressing comprising a continuous film with alternative patterns of depressions.

FIGS. 8 and 10 show a cross-section through a portion of the dressings shown in FIGS. 7 and 9 respectively.

FIGS. 11 and 12 show magnified portions of dressings of the type shown in FIGS. 1 and 5 respectively in which the land area between the depressions contains apertures.

The dressing illustrated in FIG. 1 shows a dressing (1) formed from a continuous film (2) which contains a pattern of depressions (3) in the form of a strip which lies in the centre of the dressing (1) and is the operative area of the dressing The film is formed from a moisture vapour permeable material such as a polyurethane, for example an Estane (Trade mark), an elastomeric polyester, for example a Hytrel (Trade mark) and a polyether-polyamide for example a Pebax (Trade mark). A preferred film may be prepared from a hydrophilic polymer such as a hydrophilic polyurethane which aptly contains from 20 to 40% by weight of water when hydrated. Suitable hydrophilic polyurethanes are described in United Kingdom Pat. No. 2093190B.

The film (4) which surrounds the depressions (3) is flat and could carry a coating of a skin-compatible pressure-sensitive adhesive for adhering the dressing to the skin. The pharmaceutically acceptable carrier is contained within the depressions (3).

FIG. 2 shows a cross-section through the dressing shown in FIG. 1 along the line 2--2. The figure shows the relatively small amount of land area (5) between the depressions (3). Only a small amount of this area (5) would contact the skin over the wound and hence the dressing shows lo wound adherency.

FIG. 3 shows a second embodiment of a dressing of the present invention. The dressing (6) comprises a film (7) which contains depressions (8) in the form of square pyramids the apices of which have been removed during their preparation. In this embodiment the film is completely covered by depressions. The pharmaceutically acceptable carrier (9) may be placed in any or all of the depressions (8). Prior to use the dressing is sandwiched between two removable protector layers (not shown) to prevent the carrier being ejected from the depressions for example during transportation or storage. The film is suitably formed from a blend of ethylene-vinyl acetate copolymer and polystyrene.

FIG. 4 shows a cross-section through a portion of a dressing shown in FIG. 3. The depressions (8) are caused to contain apertures (10) by removing the apices of the square pyramids in the forming process. The pharmaceutically acceptable carrier (9) is placed in the depressions (8). The land area (11) between the depressions (8) forms from 5 to 10% of the area of the film.

FIG. 5 shows a third embodiment of a dressing of the present invention. The dressing (12) comprises a film (13) which contains a pattern of conical depressions (14). In this dressing the two outer rows of the depressions (14) are not apertured while the inner rows contain an aperture (15) formed by removal of the apices of the cone during manufacture.

FIG. 6 shows a cross-section through a dressing shown in FIG. 5 along the line 6--6. The outer two rows of depressions (14) are not apertured while the centre three rows are apertured.

FIGS. 7 and 9 show dressings (16, 19) which comprise a continuous film (17, 20) which has different types of depressions (18, 21) impressed in the film. FIGS. 8 and 10 show the corresponding cross-section views of the dressings 7 and 9.

FIG. 11 shows a magnified section of the type of dressing shown in FIG. 1 which comprises a dressing (22) formed from a continuous film (23) having depressions (24) impressed out of the plane of the film. The land areas (25) contain small perforations (26) which permit transmission of wound exudate from heavily exuding wounds.

FIG. 12 shows a magnified section of the type of dressing shown in FIG. 5 which comprises a dressing (27) formed from a film (28) having conical depressions (29) the outer rows (30) of which are not apertured and the inner rows (31) which are apertured. The land areas (32) contain apertures (33) close to the non-apertured depressions (30).

A film was prepared by extruding a blend of ethylene-vinyl acetate copolymer (80 parts by weight), high impact polystyrene (20 parts by weight) and titanium dioxide (4% by weight of the weight of polymers). The film had a thickness of 75 to 100 .mu.m. A strip of the film was placed on an embossed film of polypropylene having hexagonal bosses arranged so that there are 10 embossments per sq.cm. (approx). The two films were passed in contact between the nip of two rollers under pressure, a silicone rubber coated roller and a metal roller heated to 100.degree. C. with a silicone rubber mat being in contact with the other side of the blend film. A second pass was made between a silicone rubber roller and a metal roller at 100.degree. c. to form the apertures, (if a non-apertured film is required this second pass will be omitted), whereby the excess polymer blend material from the apertures is removed on the metal roller. The embossed apertured polymer blend film was then removed from the polypropylene embossed film and then re-applied. A film of polyester was lightly adhered to the blend film over the apertures using pressure and heat. The embossed apertured film -- polyester laminate was then recovered from the polypropylene embossed film to provide the laminate of embossed apertured film containg depressions adhered to a polyester film which contacted and covered the apertures of the film.

An ointment comprising 1% silver sulphadiazine in a hydrophilic ointment was spread over the polymer blend film dressing so that the ointment entered into the depression. Any excess ointment was removed by scraping the surface with a flat blade. The presence of the polyester film prevents the ointment from running out through the apertures. The dressing may be covered by a second releaseable layer and packaged in a bacteria proof, water-proof pack and sterilised by 2.5 Mrad gamma-irradiation.

A film was prepared by extruding a blend of ethylene-vinyl acetate copolymer (90 parts by weight), high impact polystyrene (10 parts by weight) and titanium dioxide (4% by weight of the weight of polymers). The film had a thickness of 80 .mu.m. A strip of the film was placed on an embossed film of polypropylene having hexagonal embossment arranged so that there are 10 embossments per sq.cm. The two films were passed in contact between the nip of two rollers under pressure, a silicone rubber coated roller and a metal roller heated to 100.degree. C. A rigid, plain film of polyethylene was then placed onto the polymer blend film and a second pass was made between the nip of two metal rollers heated to 100.degree. C. The film sandwich was allowed to cool and the polyethylene film removed. A film of polyester (Melinex, trade mark) was lightly adhered to the embossed film over the apertures using pressure and heat. The embossed polymer blend film was then removed from the polyethylene embossed film, to provide a laminate of embossed polymer blend film adhered to a polyester film which contacted and covered the apertures of the embossed film.

An ointment was prepared by mixing together polyethylene glycol 400 (70 parts by weight), polyethylene glycol 4000 (20 parts by weight) and polyvinyl pyrrolidone -- iodine (10 parts by weight)

The ointment was spread over the polymer blend embossed film dressing so that the ointment was filled into the depressions. Any excess ointment was removed by scraping the surface with a flat blade. The presence of the polyester film prevents the ointment from running out through the apertures. The dressing may be covered by a second releasable layer and packaged in a bacteria proof, water-proof pack and sterilised by gamma-irradiation.

In use the dressing is removed from the pack and the first release layer removed, the dressing is then placed with the ointment against the skin and the polyester film is removed. An absorbent pad may be placed onto the dressing in contact with the apertures.

A polymer blend film was embossed in a similar manner to that described in Example 1. Instead of using a polyester film, a polypropylene film was vacuum formed over the embossed film to cover the apertures. The laminate could be peeled from the polyethylene embossed film because the polymer blend film adhered more strongly to the polypropylene than to the polyethylene. The ointment was then filled into the depressions as before in Example 1 and the dressing packaged an sterilised as previously.

In use the dressing was placed against the skin and the vacuum formed polypropylene peeled off.

A dressing similar to that described in Example 1 was prepared except that the ointment was formed from an oil-in-water emulsion containing silver sulphadiazine.

A dressing similar to that described in Example 1 was prepared except that the ointment was formed from an oil-in-water emulsion containing chlorhexidine di gluconate or chlorhexidine diacetate.

A film of a thermoplastic polyurethane, Estane 5714F, is placed against an embossed film of polypropylene. The two films are passed on contact between the nip of two rollers under pressure and at an elevated temperature. Depressions are formed in the polyurethane film without creating apertures. The film is removed from the embossments and an oil-in-water composition containing silver sulphadiazine is filled into the depressions and covered by a removable protector. The dressing so formed may be placed in a vacuum formed styrene tray and covered with a foil lid and sterilised.

A dressing similar to that described in Example 6 is prepared except that the film used is a polyetherpolyester elastomer, Hytrel 4056 and the composition comprises 10% polyvinyl pyrrolidone-iodine in a polyethylene glycol carrier.

A dressing similar to that describd in Example 6 is prepared using a hydrophilic polyurethane prepared in manner described in Example 2 of United Kingdom Pat. No. 2093190B. The depressions are filled with a hydrophobic ointment composition containing chlorhexidine digluconate and a surfactant.