Overview of antiandrogen therapy for hirsutism
Antiandrogens used in hirsutism include spironolactone, cyproterone, and the 5-alpha-reductase inhibitors finasteride and dutasteride. Choice of antiandrogen is influenced by adverse effect profile and pharmacokinetics; see #srg2-c16-s7-1__tsrg2-c16-tbl2. Dutasteride should be reserved for specialist use because data on its efficacy are limited and it has a very long half-life, which increases its risk of teratogenicity.
Adding an antiandrogen to a combined oral contraceptive (COC) or menopausal hormone therapy (MHT) is beneficial in females who do not respond adequately to 6 months of treatment with either therapy alone.
An antiandrogen can be used alone if a COC or MHT is contraindicated, but if used alone in females of reproductive age, a highly effective method of contraception must be used concurrently.
Antiandrogen use in pregnancy may increase the risk of defective virilisation of the male fetus. Antiandrogens should be stopped when planning pregnancy or if unplanned pregnancy occurs. The risk of unintended drug exposure during pregnancy and therefore potential teratogenicity depends on the half-life:
- finasteride and spironolactone have short half-lives (less than 24 hours); they should be stopped when the individual starts trying to conceive
- cyproterone has a longer half-life (up to 57 hours); it should be stopped 2 to 3 months before trying to conceive. Timing is influenced by individual factors (eg kidney function); seek specialist advice if there is any uncertainty1.