Transdermal drug delivery: clinical considerations for the obstetrician-gynecologist.

Introduction: The first transdermal drug delivery system was introduced in the United States over 20 years ago. Created as an alternative route of administration to improve patient compliance as well as to reduce side effects, the transdermal delivery of drugs now represents a $1.5 to $2 billion market and is growing rapidly.

Data Sources: The medical literature from 1980 to 2005 was searched using the PubMed search engine. The search term was "transdermal," limited to human clinical trials. Abstracts were used to identify clinical trials that compared transdermal preparations and their oral counterparts in the same study.

Tabulation, Integration, And Results: In this article, we review the rationale for the transdermal administration of drugs; discuss aspects of the anatomy and physiology of the skin relevant to drug transport; examine the qualities required for a drug to be a good candidate for transdermal delivery; and consider key principles for the evaluation of the relative benefits of transdermal delivery, using studies of hormone replacement therapy and oral contraceptive as examples.

Conclusion: The data reviewed here suggest that certain clinical situations support the use of the transdermal administration of drugs over their oral counterparts.