Dutasteride, manufactured by GlaxoSmithKline under the trade name Avodart, is a dual 5 alpha-reductase inhibitor, meaning that it inhibits both types 1 and 2 5-ar and that reduces the conversion of testosterone into dihydrotestosterone (DHT).
Dutasteride is currently the most powerful 5-ar inhibitor available and will lower DHT levels greatly. It is approved by the FDA for the treatment of benign prostatic hyperplasia in men, but is often prescribed off-label for the treatment of androgenic alopecia (male pattern baldness) in both men and women.
Unfortunately, there is a paucity of studies on dutasteride, particularly in relation to the treatment of women and none that have specifically focused on hirsutism.
A case study published in 2005 reported successful treatment of one woman suffering from androgenic alopecia.
”After 6 months of therapy, significant improvement was observed and after 9 months the clinical diagnosis of androgenic alopecia could no longer be made in this patient.”
A 2006 study comparing the efficacy of duatsteride with finasteride in men with male pattern baldness reported the following results at 24 weeks:
- Placebo: – 32.3 hairs
- Finasteride 5 mg: + 75.6 hairs
- Dutasteride 0.1 mg: + 78.5 hairs
- Dutasteride 0.5 mg: + 94.6 hairs
- Dutasteride 2.5 mg: + 109.6 hairs
The most common dose is 0.5 mg, however, a dose of up to 2.5 mg has been found to be well-tolerated in Phase II studies.
As with any anti-androgenic medication, the risk of birth defects in male foetuses should a woman be pregnant whilst taking dutasteride is 100% and therefore an effective contraception protocol is essential whilst on this drug and for 6 months after ceasing it. Even handling the capsules can be dangerous as dutasteride is absorbed through the skin. People taking dutasteride are unable to donate blood while they are taking the drug and for six months afterwards, due to the long half-life of the drug.
A male foetus needs testosterone in order to develop properly. The effects of anti-androgenic drugs on a developing male foetus results in physical deformities of the sexual organs and abnormalities of physiological development identical to the genetic disorder 5-alpha-reductase deficiency. This presents with a genetically male child with both X and Y chromosomes, that may have either normal male genitalia, ambiguous genitalia or even female genitalia, although they will have testes which will become hormonally active at puberty. These children are often raised as girls with the syndrome not being discovered until puberty when the testes begin to produce testosterone resulting in hirsutism, a deepening voice and potentially descending of the testes along with clitoral enlargement if the genitalia is female.
Eun HC, Kwon OS, Yeon JH, Shin HS, Kim BY, Ro BI, Cho HK, Sim WY, Lew BL, Lee WS…. (2010) Efficacy, safety, and tolerability of dutasteride 0.5 mg once daily in male patients with male pattern hair loss: a randomized, double-blind, placebo-controlled, phase III study. Journal of the American Academy of Dermatology, 63(2), 252-8. PMID: 20605255
Olsen EA, Hordinsky M, Whiting D, Stough D, Hobbs S, Ellis ML, Wilson T, Rittmaster RS, & Dutasteride Alopecia Research Team. (2006) The importance of dual 5alpha-reductase inhibition in the treatment of male pattern hair loss: results of a randomized placebo-controlled study of dutasteride versus finasteride. Journal of the American Academy of Dermatology, 55(6), 1014-23. PMID: 17110217
Olszewska M, & Rudnicka L. (2005) Effective treatment of female androgenic alopecia with dutasteride. J Drugs Dermatol, 2005 Sep-Oct;4(5), 637-40. PMID: 16167423