Background: Data suggest that androgenetic alopecia is a process dependent on dihydrotestosterone (DHT) and type 2 5α-reductase. Finasteride is a type 2 5α-reductase inhibitor that has been shown to slow further hair loss and improve hair growth in men with androgenetic alopecia. Objective: We attempted to determine the effect of finasteride on scalp skin and serum androgens. Methods: Men with androgenetic alopecia (N = 249) underwent scalp biopsies before and after receiving 0.01, 0.05, 0.2, 1, or 5 mg daily of finasteride or placebo for 42 days. Results: Scalp skin DHT levels declined significantly by 13.0% with placebo and by 14.9%, 61.6%, 56.5%, 64.1%, and 69.4% with 0.01, 0.05, 0.2, 1, and 5 mg doses of finasteride, respectively. Serum DHT levels declined significantly (P < .001) by 49.5%, 68.6%, 71.4%, and 72.2% in the 0.05, 0.2, 1, and 5 mg finasteride treatment groups, respectively. Conclusion: In this study, doses of finasteride as low as 0.2 mg per day maximally decreased both scab skin and serum DHT levels. These data support the rationale used to conduct clinical trials in men with male pattern hair loss at doses of finasteride between 0.2 and 5 mg.
Bibliographical noteFunding Information:
Chambers Hair Institute, Lutherviller; and Merck Research Laboratories,R ahways and Brussels.t The reported clinical study was entirely supported by Merck Research Laboratories, Merck & Co, Inc. Merck & Co, Inc is the company that manufactures and markets finasteride. These data were originally presented at the 55th annual meeting of the Society for Investigative Dermatology, Baltimore,M D, 1994. Accepted for publication April 27,1999. Reprint requests: Joanne Waldstreicher, ME), Senior Director, Clinical Research, Endocrinology and Metabolism, Merck Research Laboratories, PO Box 2000, Rahway,N J 07065. Copyright 9 1999 by the American Academy of Dermatology, Inc. 0190-9622/99/$8.00 + 0 16/1/100410