The effects of N,N-diethyl-4-methyl-3-oxo-4-aza-5 alpha-androstane-17 beta-carboxamide, a 5 alpha-reductase inhibitor and antiandrogen, on the development of baldness in the stumptail macaque.

We used a primate model of male-pattern baldness to test the efficacy of a topically applied 5 alpha-reductase inhibitor and antiandrogen (4-MA) in the prevention of baldness. Six periadolescent stumptail macaques were given daily topical applications of either 4-MA in dimethylsulfoxide or dimethylsulfoxide alone for 27 months. The three control monkeys developed varying degrees of baldness, while the three 4-MA-treated monkeys retained their juvenile pattern of hair growth. The percentage of actively growing hair follicles in the frontal scalp did not change in the 4-MA-treated group [46 +/- 6 (+/- SE) vs. 48 +/- 4], while a significant decrease occurred in the control group (63 +/- 6 vs. 25 +/- 12; P less than 0.025). Skin 5 alpha-reductase activity was reduced in the scalp of the 4-MA-treated monkeys. We conclude that topical 4-MA can prevent the development of baldness in the stumptail macaque, a primate model of androgen-dependent baldness.