Dutasteride, a dual inhibitor or 5 alpha reductase type 1 and 2
Dutasteride is approved in Korea for the treatment of male pattern balding. It is used "off label" in many other countries. Whereas finasteride (Propecia) inhibits 5 alpha reductase type 2, dutasteride inhibits 5 alpha reductase types 1 and 2.
Finasteride has received press on account of its side effect profile (especially sexual side effects) and possibilities of long lasting, possibly permanent side effects in a low proportion of users.
Dutasteride is known to have a similar array of overall side effects, and given the greater inhibition of 5 alpha reductase that dutasteride has, one might expect a similar if not greater number of side effects. Interestingly, this has not been the case in all studies to date. In fact, most studies support the efficacy and tolerability of dutasteride at 0.5 mg with relatively low incidence of side effects.
A new study published by Choi et al looked at over 700 men ranging in age from 18-41. These men were using dutasteride at 0.5 mg. The frequency of side effects were low. 1.3 % of patients experienced decreased libido, impotence in 1 %, fatigue in 0.7 %, breast enlargement was seen in 0.3 %. Over 79 % of men reported improvement with their hair.
This study was not set up to compare dutasteride to placebo. This was simply an observational study as part of routine "post marketing" surveillance. Overall, the findings are encouraging and expected- pointing to a low risk of adverse events with this dual inhibitor of 5 alpha reductase.
Choi GS et al. Ann Dermatol. 2016 Aug;28(4):444-5
Dr. Jeff Donovan is a Canadian and US board certified dermatologist specializing exclusively in hair loss. To schedule a consultation, please call the Vancouver office at 604.283.9299