Maxwell Enterprises

Finasteride is a synthetic antiandrogen that acts by inhibiting type II 5-alpha reductase, the enzyme that converts testosterone to dihydrotestosterone (DHT). It is used as a treatment in benign prostatic hyperplasia (BPH) in low doses, and prostate cancer in higher doses. A May, 2008 study indicates that finasteride reduces the rate of prostate cancer by 30%. It is also indicated for use in combination with doxazosin therapy to reduce the risk for symptomatic progression of BPH. In addition, it is registered in many countries for androgenetic alopecia (male-pattern baldness).

Finasteride was approved initially in 1992 as Proscar, a treatment for enlarged prostate, but the sponsor had studied 1 mg of finasteride and demonstrated hair growth in male pattern hair loss. Merck sells it under the brand name Propecia.

Health organizations and practicing clinicians have expressed concerns that Propecia gives rise to persistent side-effects in some men.