Healing wounds

Researchers at

have developed a new drug delivery system for treating wounds which overcomes a major hurdle in conventional treatments. The dry wafer system, developed by RGU's School of Pharmacy, will be reported next week at the British Pharmaceutical Conference in Manchester.

The freeze-dried wafers are made from polymer gels, which are designed to be applied directly to the surface of suppurating wounds, such as chronic leg ulcers or pressure sores. Once in place, the wafer absorbs fluid from the wound and reverts to being a viscous gel, from which the contained drug can diffuse to the target area.

The dried wafer overcomes a major hurdle with conventional wound treatments. Dr. Kerr Matthews, who is leading the research at RGU's School of Pharmacy explains, "With conventional products, such as gels and creams, it is difficult to apply an exact amount of drug to the wound, especially if there is a high degree of suppuration. In addition, if a gel is diluted by fluid exuding from a wound its viscosity will be reduced and so the gel may run from the target area, taking the therapeutic agent with it."

The innovative aspect of the wafer is that it relies on the presence of exudate to form a viscous gel. The rate at which the wafers absorb wound exudate and form viscous gels can be tailored to suit the varying degrees of suppuration encountered with different types of wound.

In initial studies, the inner surface of an over-ripe melon was used as a model for a suppurating wound surface. These studies showed that the wafer does stick to the wound surface and absorb fluid.

Therapeutic agents that might be included in the wafers include antibiotics and the new growth factors that are being developed to encourage tissue growth. These growth factors are very expensive drugs and so require reliable delivery.

The wafers need to be sterile for application to a wound. Experimental results, which will be reported to the British Pharmaceutical Conference, showed that the wafers could withstand sterilising doses of gamma irradiation without losing their desired properties.

Dr. Matthews said, "Early results indicate that the production of a sterile, wound-healing wafer is feasible. The attraction of this technology is its simplicity and the fact that the wafers are made from cheap materials that are already approved for medicinal use."