Abstract

Finasteride is a type 2 5 alpha-reductase inhibitor that inhibits conversion of testosterone to dihydrotestosterone, a key mediator of male pattern hair loss (androgenetic alopecia). The objective of this study was to identify the optimal dosage of finasteride and to evaluate its efficacy and safety in the treatment of Japanese men with male pattern hair loss. In this double- blind randomized study, 414 Japanese men with male pattern hair loss received finasteride 1 mg (n = 139), finasteride 0.2 mg (n = 137), or placebo (n = 38) once daily for 48 weeks. Efficacy was evaluated by global photographic assessment, patient self-assessment, and investigator assessment. All efficacy endpoints showed significant improvement with finasteride therapy by 12 weeks (p < 0.05 versus placebo). At 48 weeks, 58%, 54%, and 6% of men in the finasteride 1 mg, finasteride 0.2 mg, and placebo groups, respectively, had improved based on assessments of global photographs. All efficacy endpoints were numerically superior for the 1 mg dose over the 0.2 mg dose at 48 weeks. Finasteride treatment was generally well tolerated. Finasteride 1 mg\day slows hair loss and improves hair growth in Japanese men with male pattern hair loss.