Transdermal delivery of steroids.

The advantages of delivering drugs through the skin for systemic therapy have been widely recognized and represent a growing sector in drug development. Transdermal delivery of steroids is also a rapidly expanding field and in various clinical situations where hormonal replacement therapy is needed this route of administration is a real breakthrough, considering the relative toxicity of some steroids when given orally. Various transdermal systems have been designed, all of them aimed at achieving a constant release rate of the molecules contained in their reservoir through the intact skin. The skin itself, and especially the outermost layer, the stratum corneum, can play the roles of a reservoir and a rate-controlling membrane. So far, estradiol, progesterone and testosterone have been demonstrated to be good candidates for transdermal delivery. The effectiveness and the acceptability of transdermal delivery of estradiol in postmenopausal women have been demonstrated. The efficacy of topical administration of progesterone in patients with benign breast disease has also been proved. More recently, the high rate of acceptability and efficacy of transdermal testosterone in male hypogonadism has been demonstrated. The transdermal delivery of steroids is therefore expected to make a significant impact on the quality of patient care both in men and in women.