O#02   Safety and efficacy of finasteride 1 mg (Propecia®) in the treatment of androgenetic alopecia

Antonella Tosti1, Keith D. Kaufman2. 1Dept of Dermatology, University of Bologna, Bologna, Italy. 2Merck Research Laboratories, Rahway, NJ, USA

Propecia® (finasteride 1 mg), a selective inhibitor of the human type 2 5a-reductase enzyme, was launched in 1998 as the first oral pharmacologic therapy for men with androgenetic alopecia (AGA). Dose-ranging studies provided initial evidence of the beneficial effects of finasteride in men with AGA and established 1 mg as the optimal dose. The safety and efficacy profile of finasteride 1 mg was subsequently established in 3 Phase III studies (N=1879) in men with AGA : 2 replicate 2-year studies in men with predominantly vertex hair loss and a 1-year study in men with predominantly frontal hair loss. In all 3 studies, finasteride treatment led to significant improvements in hair growth and slowing of further progression of hair loss vs. placebo, based on 4 predefined endpoints (hair counts, patient self-assessment, investigator assessment, and standardized clinical photography). Data from placebo-controlled extensions to the Phase III vertex studies for up to 5 years demonstrated that long-term treatment with finasteride led to durable improvements in hair growth and slowing of further hair loss. Histologic evaluation of scalp biopsies demonstrated that finasteride treatment led to a significant increase in terminal anagen hairs, associated with trends towards a decrease in vellus hairs and an increase in the terminal to vellus hair ratio, suggesting reversal of follicular miniaturization. Phototrichogram analysis confirmed that finasteride increased the number of anagen hairs and improved the anagen to telogen ratio. Finasteride was also shown to increase hair weight to a greater extent than hair count, implying that factors other than the number of hairs, such as increased growth rate and thickness of hairs, contribute to its beneficial effects. Finasteride was generally well tolerated in these studies, and side effects related to treatment were limited to reversible impairment of sexual function in a small number of men. In contrast to the benefits observed in men, finasteride was not effective in the treatment of postmenopausal women with AGA, a finding confirmed by histologic evaluation of scalp biopsies. These data suggest a differing pathophysiology of AGA in women compared to men. In conclusion, chronic therapy with finasteride is generally well tolerated in men with AGA, and leads to durable improvements in hair growth and slowing of further progression of hair loss.