The effects of finasteride on scalp skin and serum androgen levels in men with androgenetic alopecia

Background: Data suggest that androgenetic alopecia is a process dependent on dihydrotestosterone (DHT) and type 2 5 alpha-reductase. Finasteride is a type 2 Sa-reductase inhibitor that has been shown to slow further hair los s and improve hair growth in men with androgenetic alopecia. Objective: We attempted to determine the effect of finasteride on scalp ski n 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 significa ntly (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 max imally decreased both scalp skin and serum DHT levels. These data support t he rationale used to conduct clinical trials in men with male pattern hair loss at doses of finasteride between 0.2 and 5 mg.