A transdermal patch uses a special membrane to control the rate at which the liquid drug contained in the reservoir within the patch can pass through the skin and into the bloodstream. The basic components of any transdermal delivery system include the drug(s) dissolved or dispersed in a reservoir or inert polymer matrix; an outer backing film of paper, plastic, or foil; and a pressure-sensitive adhesive that anchors the patch to the skin. The adhesive is covered by a release liner, which needs to be peeled off before applying the patch to the skin.
Drugs administered via skin patches include scopolamine, nicotine, estrogen, nitroglycerin, and lidocaine. Basically the molecules of the medication must be small enough to pass through the skin
This is a non invasive way to treat many diseases and disorders. In addition to the aspects of each patch - there are four types of transdermal patches. These four types are: Single layer drug in adhesive, multi layer drug in adhesive, reservoir and matrix.