Permeation enhancers compatible with transdermal drug delivery systems. Part I: selection and formulation considerations.

Part I of this article reviews the classification, chemistry, properties, selection, and use of skin permeation enhancers in transdermal drug delivery systems and dermal patches. The authors discuss ideal properties of enhancers and describe various enhancers' actions on the skin. Part II will describe interactions between permeation enhancers and other transdermal delivery system components, such as backing materials, pressure-sensitive adhesives, membranes, and release liners. Adhesive properties critical to the optimization of a transdermal formulation will be discussed.