Transdermal and topical patches

Single- and multilayer transdermal and topical patches are designed to act either locally or systemically, depending on the site of action of the active substance. Hydrogel and Drug-in-adhesive technologies are patent-protected.

The structure of these patches is usually composed of a polyacrylate, silicone or other adhesive matrix containing the active substance, a support layer and a protective layer to be removed before application; it can also be more complex, for example, include multiple layers of adhesive containing different concentrations of the active substance.

Patches for topical use can be either formulated to have a local action over a limited area (e.g. diclofenac and piroxicam) or transdermal, with a systemic action (e.g. nitro-glycerine and fentanyl). Patches for topical use are able to release a medicinal product in a controlled manner, over periods of time that vary from a few hours to a week, offering a great many advantages over oral administration, such as:

• maintenance of optimum concentrations of the medicinal product;
• reduction in the frequency of administration;
• better tolerability.