Skin sensitivity and transdermal drug delivery. A review of the problem

Transdermal devices are now marketed for the delivery of systemic medication through the skin. Advantages associated with transdermal drug delivery include avoidance of first-pass metabolism and improved patient compliance. Drugs currently available by this route include scopolamine (hyoscine), nitroglycerin (glyceryl trinitrate), estradiol, nicotine and clonidine. This novel development has brought in its wake a specific constellation of skin sensitivity problems, which vary widely in incidence between drugs. Varying the site of drug administration to minimise these reactions is important. Any eczematous reaction can be treated with a moderately potent topical steroid. Tolerance to oral challenge in those with topical sensitivity occurs, but caution is still advocated before proceeding to this step. The increasing use of transdermal drug delivery systems across many specialties means that problems of skin sensitivity are of growing relevance to the dermatologist, the hospital specialist and the primary care physician.