m mm The effects of f'masteride on scalp skin and serum androgen levels in men with androgenetic alopecia Lynn Drake, MD, a Maria Hordinsky, MD, b Virginia Fiedler, MD, c James Swinehart, MD, d Walter P. Unger, MD, e Paul C. Cotterill, MD, f Diane M. Thiboutot, MD,g Nicholas Lowe, MD, h Coleman Jacobson, MD, i David Whiting, MD,J Sam Stieglitz, MD, k Stephen J. Kraus, MD, 1 Edmond I. Griffin, MD, l Darryl Weiss, MD, m Patrick Carrington, MD, n Christopher Gencheff, DO, ~ Gary W Cole, MD,P David M. Pariser, MD,q Edwin S. Epstein, MD, r Wesley Tanaka, PhD, s Aim~e DaUob, MS, s Kristel Vandormael, MS, t Lori Geissler, BS, s and Joanne Waldstreicher, MD s Oklahoma City, Oklahoma; Minneapolis, Minnesota; Chicago, Illinois; Denver, Colorado; Toronto, Ontario, Canada; Hershey, Pennsylvania; Santa Monica and Irvine, California; Dallas, Texas; Tampa, Florida; Atlanta, Georgia; Fairlawn and Rahway, NewJersey; Little Rock, Arkansas; Madison, Wisconsin; Norfolk, Virginia; Lutherville, Maryland; and Brussels, Belgium Background: Data suggest that androgenetic alopecia is a process dependent on dihydrotestosterone (DHT) and type 2 5a-reductase. Finasteride is a type 2 5~z-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 scalp 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. (I Am Acad Dermatol 1999;41:550-4.) B ody hair growth in scalp, pubic, axillary, and facial areas is an androgen-dependent process. Many androgen target tissues in men, including the prostate and scalp hair follicles, are more responsive to dihydrotestosterone (DHT) than testosterone (T). Two types of 5{z-reductase (5erR) enzymes, which convert T to DHT, are present in humans. 1-3 Scalp skin contains type 1 50~R in the From the University of Oklahoma Health SciencesCenter,Oklahoma Citya; the University of Minnesota Twin Cities, Minneapolisb;the University of Illinois, Chicagoc;the Colorado Medical Research Center, Denverd; the University of Toronto, Ontarioe;Sunny Brook Hospital, Toronto, Ontariof; Penn State University College of Medicine, Hersheyg;Clinical ResearchSpecialists, Santa Monicah; the University of TexasSouthwestern Medical Center) and Dallas Associated Dermatologists) Dallas; the Alpha Omega Hair and Scalp Clinic, Tamp@; the GeorgiaClinical Research Center, Atlantal; the Plastic Surgery and Dermatology Center, Fairlawnm; the University of Arkansas for Medical Sciences, Little Rockn; the Lakeview Medical Center,Madisono;the University of California, IrvineP; Pariser Dermatology Specialty Limited, Norfolkq; the Chambers Hair Institute, Lutherviller; and Merck Research Laboratories, Rahway s and Brussels. t The reported clinical study was entirely supported by Merck Research Laboratories, Merck & Co, Inc. Merck & Co, Inc is the company that manufacturesand markets finasteride. These data were originally presented at the 55th annual meeting of the Societyfor Investigative Dermatology,Baltimore, MD, 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, NJ 07065. Copyright 9 1999 by the American Academyof Dermatology,Inc. 0190-9622/99/$8.00 + 0 16/1/100410 550