United States of America. The Food and Drug Administration has approved finasteride (PropeciaR: Merck, tablet 1 mg) for the treatment of male pattern baldness, making it the first such treatment in pill form.

Finasteride was first approved in 1992 (ProscarR: Merck, 5 mg) as a treatment for prostate enlargement. It was observed that some patients being treated for prostate enlargement had some regrowth of hair in areas of male pattern hair loss.

The manufacturer studied the use of finasteride at a dosage of 1 mg and demonstrated hair growth in male pattern hair loss. The number of hairs increased in the anterior midscalp and vertex. Adverse reactions were infrequent and were related to sexual function. The drug will not be marketed for women because it causes birth defects, and safety and efficacy have not been established in women.

Reference: FDA Talk Paper T97-66 dated 22 December 1997.