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


METHODS
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.


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.


CONCLUSIONS
The data reviewed here suggest that certain clinical situations support the use of the transdermal administration of drugs over their oral counterparts.
Potts
Russell O
RO
Russ Potts Consulting, LLC, San Francisco, California, USA. russ@vosspotts.org
Lobo
Rogerio A
RA
D000279:Administration, Cutaneous; D000368:Aged; D003271:Contraceptive Agents, Female / Q000008:administration & dosage*; D003692:Delayed-Action Preparations / Q000627:therapeutic use*; D016503:Drug Delivery Systems; D005260:Female; D020249:Hormone Replacement Therapy / Q000379:methods*; D006801:Humans; D008593:Menopause / Q000187:drug effects*; D008875:Middle Aged; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D012869:Skin Absorption / Q000502:physiology; D014550:Urinary Incontinence, Stress / Q000188:drug therapy*
D003271:Contraceptive Agents, Female; D003692:Delayed-Action Preparations