In the United States, the two approved pharmacologic agents for treatment of male pattern hair loss are topical minoxidil (Rogaine) and systemic finasteride 1 mg/d (Propecia). The mechanism by which finasteride enhances hair growth is related to its activity as a 5-alpha-reductase inhibitor (5-ARI), which prevents the conversion of testosterone in the skin to its active derivative dihydrotestosterone (DHT). Since DHT is believed to be the primary culprit inducing male pattern hair loss, diminution of its activity results in reduced hair loss and allows better unrestrained hair regrowth.
The 5-ARI activity of finasteride is designated as type 2. Because there are multiple 5-ARI isoenzymes (types 1, 2, and 3), the potential role of dutasteride — which is active at both type 1 and type 2 tissue sites — is of interest. Indeed, dutasteride is already approved in Korea for treatment of male pattern baldness.
A placebo-controlled, randomized, head-to-head (no pun intended, honest) trial compared hair growth in men with male pattern baldness treated with finasteride 1 mg/d vs dutasteride 0.02-0.5 mg/d for 6 months (n = 917).
At the end of the trial, although both active agents were superior to placebo, there was a significant difference favoring dutasteride for both absolute hair count as well as hair width compared to finasteride. Dutasteride may become a viable alternative to finasteride for male pattern hair loss.
Source: Harcha WG, et al. J Am Acad Dermatol 2014;70:489-498.