Is there a role for finasteride in treating polycystic ovary syndrome (PCOS)?

Role of Finasteride in Treating Polycystic Ovary Syndrome (PCOS)

Finasteride can be recommended for PCOS patients with hirsutism, particularly those with refractory symptoms or endocrine co-morbidities, as it effectively reduces hirsutism scores by inhibiting 5α-reductase activity. 1

Mechanism of Action and Efficacy

Finasteride is an inhibitor of 5α-reductase that blocks the conversion of testosterone to dihydrotestosterone (DHT), which is the more potent androgen responsible for hirsutism in PCOS. The evidence shows:

• Finasteride produces significant reduction (>50%) in hirsutism scores in both idiopathic hirsutism and PCOS-associated hirsutism 2
• It effectively reduces serum dihydrotestosterone and 3α,17β-androstenediol glucuronide levels without affecting other androgen levels 2
• Improvement in hirsutism can be observed as early as 3 months after initiating treatment 3

Dosing and Administration

• Standard dosing: 5 mg daily 2, 3
• Alternative dosing: 2.5 mg every 3 days has shown similar efficacy with fewer side effects 4
• Treatment duration: Maximum therapeutic effect is typically achieved after 6 months in PCOS patients 3

Clinical Applications in PCOS Management

Finasteride should be considered in the following scenarios:

1. Hirsutism treatment: As part of a combination approach with ovarian suppression agents 5
2. Refractory cases: When first-line treatments for hirsutism have failed 1
3. Patients with endocrine co-morbidities: Particularly beneficial in PCOS patients with other endocrine disorders 1

Important Considerations and Limitations

• Pregnancy contraindication: Finasteride is absolutely contraindicated in pregnant women or women trying to conceive due to risk of feminization of male fetuses
• Combination therapy: Often more effective when combined with other treatments such as oral contraceptives 1
• Not first-line: For most PCOS patients, lifestyle modifications, metformin, and combined oral contraceptives remain the first-line treatments 5, 6
• Limited evidence: While clinical studies show effectiveness for hirsutism, larger randomized controlled trials specifically for PCOS are still needed 7

Monitoring

• Regular follow-up every 3-6 months to assess hirsutism improvement using the Ferriman-Gallwey scoring method
• Monitor for potential side effects, which may include decreased libido
• Ensure adequate contraception in women of reproductive age

Alternative Treatments for Hirsutism in PCOS

If finasteride is not suitable, consider:

• Spironolactone (improves hirsutism in 85% of patients) 5
• Eflornithine hydrochloride cream (13.9%) as an adjunctive topical treatment 5
• Combined oral contraceptives with anti-androgenic properties 5
• Cyproterone acetate, flutamide, or other peripheral androgen blockers 7

In conclusion, while finasteride is not a first-line treatment for PCOS overall, it has a specific role in managing hirsutism associated with PCOS, particularly in refractory cases or those with endocrine co-morbidities. Its use should be carefully considered alongside the comprehensive management approach for PCOS that includes lifestyle modifications, insulin-sensitizing agents, and hormonal treatments as appropriate.