Delivery of physiologically or antimicrobially active chemical species to provide a medical benefit to a skin site, e.g. a wound, is of continuing interest.
A convenient route for delivery is via a skin dressing, typically packaged and available for use by the end user for direct topical application as desired.
However a large number of physiologically or antimicrobially active species are difficult to administer from such a skin dressing. A particular difficulty arises when the active species is highly reactive and therefore unstable with a short shelf life.
One way to overcome this problem of reactivity is to generate the physiologically active species in the dressing shortly before or during application of the skin dressing. In this way, stable precursor materials are converted into reactive materials only when they are needed.
WO 03/090800 discloses a skin dressing where hydrogen peroxide is generated within a dressing through the action of an enzyme and atmospheric oxygen.
WO 2006/095193 discloses a dressing where reactive and unstable nitric oxide is generated in a skin dressing during use.
However one problem with this approach is that the dressings tend to be more complex than widely used inactive dressings, often requiring separate components to be brought together at the moment of use. The need for oxygen to be available for the enzyme is another problem, especially when the enzyme-containing dressing is covered by a protective film or outer bandage.
It would therefore be highly desirable to develop a skin dressing which is able to deliver reactive physiologically active species and is more convenient to use.