A study published by Olsen et. al. in the Journal of the American Academy of Dermatology 2006; 55(6): 1014-1023, showed the benefit of combined type I and type II 5?-reductase inhibition in the treatment of male pattern hair loss in a randomized, placebo-controlled study of dutasteride versus finasteride.
In the study, 416 men with male pattern hair loss (MPHL) ages 21 to 45 years old were randomized to receive dutasteride 0.05, 0.1, 0.5 or 2.5 mg, finasteride 5 mg, or placebo daily for 24 weeks. The results of the study showed that dutasteride increased hair counts in a dose-dependent fashion and dutasteride 2.5 mg was superior to finasteride 5mg at 12 and 24 weeks.
Dutasteride caused scalp and serum dihydrotestosterone levels to decrease and testosterone levels to increase in a dose-dependent fashion. Whereas 5-mg finasteride decreases serum DHT by about 70%, dutasteride can decrease serum DHT by more than 90%.
In this phase II, dose-ranging study, 2.5-mg dutasteride was superior to 5-mg finasteride in improving scalp hair growth in men between ages 21 and 45 years with MPHL as judged by target area hair counts, expert panel assessment, and investigator assessment at 12 and 24 weeks.
