Finasteride Dosing for Postmenopausal Hirsutism
The recommended dose of finasteride for postmenopausal hirsutism is 2.5 mg daily, which is as effective as the higher 5 mg dose but with fewer side effects and lower cost. 1, 2
Dosing Options and Efficacy
- Low-dose finasteride (2.5 mg/day) has been shown to significantly reduce hirsutism scores by approximately 55.7% after 12 months of treatment 1
- High-dose finasteride (5 mg/day) shows similar efficacy to the 2.5 mg dose, with no significant advantage in hirsutism reduction 2
- Intermittent dosing (2.5 mg every 3 days) may be considered as an alternative regimen with similar efficacy to daily administration but with fewer side effects 3
Treatment Duration and Response
- Clinical improvement in hirsutism typically begins within 3 months of treatment initiation 4
- Maximum therapeutic effect is observed after 6-12 months of continuous treatment 4, 5
- The percent reduction in hirsutism scores at 6 and 12 months averages 25.8% and 41.3% respectively 5
Mechanism and Rationale
- Finasteride is a 5α-reductase inhibitor that blocks the conversion of testosterone to dihydrotestosterone (DHT), which is the primary androgen responsible for hirsutism 1, 4
- The American College of Obstetricians and Gynecologists (ACOG) recognizes finasteride as one of several antiandrogen drugs used for hirsutism treatment in PCOS, though treatment is often palliative rather than curative 6
Monitoring and Safety Considerations
- Hormone levels generally remain stable during treatment with low-dose finasteride, with no significant changes in FSH, LH, testosterone, or androstenedione 1, 2
- Higher doses (5 mg/day) may increase estradiol levels significantly at 6 and 12 months of treatment 2
- Finasteride is generally well-tolerated with no serious side effects reported in studies of hirsute women 1, 5
Combination Therapy
- ACOG recommends that combined medical interventions may be the most effective approach to hirsutism 6
- The combination of an antiandrogen (such as finasteride) with an ovarian suppression agent appears to be effective in women with PCOS 6, 7
- Concomitant medical management directed at reducing androgen levels is usually necessary alongside other hair removal methods 6, 7
Important Caveats
- Finasteride is not FDA-approved specifically for hirsutism treatment; the FDA has only labeled topical eflornithine hydrochloride cream for hirsutism 6
- Finasteride is contraindicated in women who are or may become pregnant due to potential teratogenic effects on male fetuses 8
- Weight loss of at least 5% of initial body weight should be recommended as an adjunct to pharmacological treatment, as it can improve metabolic and reproductive abnormalities in PCOS 6, 7