Oral: dutasteride -0.5 mg capsule once daily
-not approved yet for alopecia
Avodart (trade name)- approved in 2002
Mode of Action
Dutasteride is a 5-alpha reductase inhibitor somewhat similar to finasteride; however, dutasteride blocks both 5AR l and 5AR ll whereas finasteride is only a 5AR ll inhibitor. It lowers serum DHT up to 95% compared to 66% for finasteride. In addition, its half-life in the serum is much longer than for finasteride- 5 weeks for dutasteride compared to 6-8 hrs for finasteride.
Studies have shown dutasteride to be equal to and usually slightly greater in effect for hair growth as compared to finasteride. 2.5 mg dutasteride daily has shown a moderately higher growth than 0.5mg dutasteride daily.
As with finasteride, dutasteride should not be taken or handled by a women who is pregnant or who may become pregnant because of the drug’s potential for causing abnormal development of a fetus. Side effects of dutasteride are similar to those reported for finasteride—decreased libido (sex drive), erectile dysfunction, male breast enlargement and psychological depression.
In one double-blind study, 2/70 patients on 0.5mg daily had decreased libido 2/70 had impotence. 3/70 on a placebo developed impotence. 9/71 taking dutasteride 2.5mg daily had impotence, indicating a correlation with dose size.
Fertility: Another study showed a 25-28% decrease in sperm count in a one year trial. 6 months after discontinuing dutasteride the sperm count was still decreased by 23%. Semen volume followed these same percentages. The sperm morphology appeared normal.
Drug interactions reported from use of dutasteride include interference with some antibiotics, some anti-depression and anti-anxiety medications, and some drugs used to treat HIV/AIDS
Dutasteride is a reasonable alternative to finasteride but some doctors are reluctant to use it because of its long half-life in the body. If wanting to use a 5AR inhibitor while starting a family, finasteride is the better choice. If the patient has a naturally low sperm count, it would be wise to avoid both drugs while trying to achieve pregnancy.