Enzyme-sensitive therapeutic wound dressings
The invention provides a wound dressing comprising a therapeutic agent and a matrix comprising polymers joined by cross-linkages which cross-linkages comprise oligopeptidic sequences which are cleavable by a protease associated with wound fluid such that the rate of release of the therapeutic agent increases in the presence of the protease.
1 . A wound dressing comprising a therapeutic agent and a matrix comprising polymers joined by cross-linkages which cross-linkages comprise, or consist of, oligopeptidic sequences which are cleavable by a protease associated with wound fluid such that the rate of release of the therapeutic agent increases in the presence of the protease.
2 . A wound dressing according to claim 1 wherein the protease is associated with wound infection or ulcer formation.
3 . A wound dressing according to claim 1 or 2 wherein the polymers themselves are not degraded by the protease or other factors that may be present in the wound environment.
4 . A wound dressing according to claim 1 , 2 or 3 wherein the polymer is a synthetic polymer.
5 . A wound dressing according to claim 4 wherein the polymer is a polymer of N-(2-hydroxypropyl)methyacrylamide (HPMA).
6 . A wound dressing according to any one of the preceding claims wherein the oligopeptidic sequences consist of 3 to 15 amino acids.
7 . A wound dressing according to any one of the preceding claims wherein the protease is elastase and wherein the oligopeptidic sequence comprises or consists of lys-gly-ala-ala-ala-lys (SEQ ID NO: 1) -Ala-Ala-Ala-, Ala-Ala-Pro-Val (SEQ ID NO: 2), Ala-Ala-Pro-Leu (SEQ ID NO: 3), Ala-Ala-Pro-Phe (SEQ ID NO: 4), Ala-Ala-Pro-Ala (SEQ ID NO: 5) or Ala-Tyr-Leu-Val (SEQ ID NO: 6).
8 . A wound dressing according to any one of claims 1 to 6 wherein the protease is a matrix metalloproteinase and wherein the oligopeptidic sequence comprises or consists of -Gly-Pro-Y-Gly-Pro-Z- (SEQ ID NO: 7), -Gly-Pro-Leu-Gly-Pro-Z- (SEQ ID NO: 8), -Gly-Pro-Ile-Gly-Pro-Z- (SEQ ID NO: 9), or -Ala-Pro-Gly-Leu-Z- (SEQ ID NO: 10), where Y and Z are amino acids.
9 . A wound dressing according to any one of claims 1 to 6 wherein the protease is a collagenase and wherein the oligopeptidic sequence comprises or consists of -Pro-Leu-Gly-Pro-D-Arg-Z- (SEQ ID NO: 11), -ProLeu-Gly-Leu-Leu-Gly-Z- (SEQ ID NO: 12), -Pro-Gln-Gly-Ile-Ala-Gly-Trp- (SEQ ID NO: 13), -Pro-Leu-Gly-Cys (Me)-His- (SEQ ID NO: 14), -Pro-Leu-Gly-Leu-Trp-Ala- (SEQ ID NO: 15), -Pro-Leu-Ala-Leu-Trp-Ala-Arg- (SEQ ID NO: 16), or -Pro-Leu-Ala-Tyr-Trp-Ala-Arg- (SEQ ID NO: 17), where Z is an amino acid.
10 . A wound dressing according to any one of claims 1 to 6 wherein the protease is a gelatinase and wherein the oligopeptidic sequence comprises or consists of -Pro-LeuGly-Met-Trp-Ser-Arg- (SEQ ID NO: 18).
11 . A wound dressing according to any one of claims 1 to 6 wherein the protease is thrombin and wherein the oligopeptidic sequence comprises or consists of -Gly-Arg-Gly-Asp- (SEQ ID NO: 19), -Gly-Gly-Arg-, -Gly-Arg-Gly-Asp-Asn-Pro- (SEQ ID NO: 20), -Gly-Arg-Gly-Asp-Ser- (SEQ ID NO: 21), -Gly-Arg-Gly-Asp-Ser-Pro-Lys- (SEQ ID NO: 22), -Gly-Pro-Arg-, -Val-Pro-Arg-, or -Phe-Val-Arg-.
12 . A wound dressing according to any one of claims 1 to 6 wherein the protease is stromelysin and wherein the oligopeptidic sequence comprises or consists of -Pro-TyrAla-Tyr-Trp-Met-Arg- (SEQ ID NO: 23).
13 . A wound dressing according to any one of the preceding claims wherein the therapeutic agent is an antimicrobial agent, a pain relieving agent, an antiseptic, an analgesic, a local anaesthetic, or a protease inhibitor.
14 . A wound dressing according to any one of the preceding claims wherein the therapeutic agent is incorporated within the matrix.
15 . A wound dressing according to claim 14 wherein the wound contacting layer of the dressing may comprise or consist of the matrix within which the therapeutic agent is incorporated.
16 . A wound dressing according to claim 15 wherein the dressing comprises a liquid permeable wound contacting layer, an intermediate layer comprising or consisting of the matrix within which the therapeutic agent is incorporated and an outer, liquid-impervious backing layer.
17 . A wound dressing according to any one of claims 1 to 13 wherein the dressing comprises a barrier layer which comprises the matrix, the barrier layer being for initially separating the therapeutic agent in the wound dressing from wound fluid when in use.
18 . A wound dressing according to claim 17 wherein the barrier layer comprises an apertured sheet having a composition comprising the cross-linked polymers applied thereto in occlusive fashion.
19 . A wound dressing according to claim 17 or 18 , wherein a layer of the therapeutic substance is provided behind the barrier layer.
20 . A wound dressing according to claim 19 , wherein an absorbent layer is provided behind the barrier layer and the therapeutic substance is dispersed in the absorbent layer.
21 . A wound dressing according to claim 17 , wherein the barrier layer substantially encapsulates the therapeutic substance.
22 . A wound dressing according to any one of the preceding claims wherein the wound dressing comprises an absorbent layer and/or a backing layer.