ABSTRACT
In the coming years, therapeutic peptides and proteins are going to gain increasing importance as a result of rapid strides in the biotechnology industry. The therapeutic application and market introduction of this new generation of therapeutic agents will require parallel development of efficient delivery systems by the pharmaceutical industry. Because of their polypeptide nature, peptide and protein drugs are destroyed in the gastrointestinal tract and must be administered parenterally. These are invasive routes which involve the inconvenience of injections and add to the cost of the health care system if administered under medical supervision. Thus, non-invasive methods of administration would be preferred. The skin, with its accessibility, enormous surface area and possibility for site targeting, offers a potential means of non-invasive delivery. Several drugs are now available on the market as transdermal patches. However, none of these is a peptide or protein drug. This is because the skin is ordinarily permeable only to small lipophilic molecules, a criterion readily fulfilled by drugs such as nitroglycerine, scopolamine, clonidine, nicotine and other drugs on the market. Peptide and protein drugs, being hydrophilic and macromolecular in nature, do not readily permeate the skin.
