The AGA Treatment Revolution 55　　 Dutasteride

Dutasteride is also a new option available.

　There are two types of 5α-reductase that convert testosterone to dihydrotestosterone: Type II and Type I. Type II is involved in male pattern baldness at the hair follicle cells in areas such as the frontal and vertex regions. Type I is present in the hair follicle cells of areas less prone to male pattern baldness, such as the temporal and occipital regions, as well as other body hair.

　Finasteride inhibits Type II, but a medication that inhibits both Type II and Type I has been developed, which is Dutasteride. Type I is also abundant in the prostate, and dihydrotestosterone produced there is involved in prostate enlargement. Dutasteride, which inhibits both Type II and Type I, is widely used worldwide as a treatment for prostate enlargement, and it is approved and used for the treatment of male pattern baldness in Japan and Korea.

The trade name for prostate enlargement treatment is Avodart, and for male pattern baldness treatment, it is Zagallo. In Japan, the Ministry of Health, Labour and Welfare approved Zagallo (0.1 mg, 0.5 mg) in 2015, and it was launched in 2016. Like finasteride, a continuous administration for usually six months is required before effects can be confirmed.

Dutasteride, which broadly inhibits the action of 5α-reductase, is said to show a higher effect on male pattern baldness than finasteride. Its active ingredient has a half-life of several weeks, allowing it to remain in the body for a long time. It was developed by GlaxoSmithKline (GSK), based in the UK. More affordable generic drugs have already been introduced as well. However, while it is more effective, reports of side effects such as decreased libido and erectile dysfunction (ED) are slightly more common than with finasteride.

Similar to finasteride, administering dutasteride to pregnant women or women who may be pregnant, as well as nursing women, can adversely affect the normal development of the external genitalia of male fetuses, and its use in women is contraindicated. Its safety in underage males has also not been established.

Recommendation level: A (for male pattern baldness), D (for female pattern baldness)

Recommendation statement: Strongly recommend the oral administration of dutasteride for male pattern baldness. However, it should not be done for female pattern baldness."

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