What is the recommended dose of finasteride (Finasteride) for benign prostatic hyperplasia (BPH) and androgenetic alopecia?

Recommended Dosage of Finasteride for BPH and Androgenetic Alopecia

The recommended dose of finasteride is 5 mg once daily for benign prostatic hyperplasia (BPH) and 1 mg once daily for androgenetic alopecia (male pattern baldness). 1, 2

Dosage for Benign Prostatic Hyperplasia (BPH)

Recommended Dose

• 5 mg oral tablet once daily
• Maximum efficacy is typically achieved after 12 months of continuous therapy 1
• Should be taken for at least 6 months to properly assess therapeutic response 2

Mechanism of Action and Efficacy

• Finasteride is a competitive and specific inhibitor of Type II 5α-reductase enzyme
• Reduces DHT (dihydrotestosterone) concentration by approximately 70% with daily dosing 2
• Reduces prostate volume by 20-30% after 6-12 months of therapy 1
• Decreases risk of disease progression:
  • 67% reduction in risk of acute urinary retention
  • 64% reduction in need for BPH-related surgery 1

Clinical Considerations

• An early improvement in urinary symptoms may be seen in some patients, but a therapeutic trial of at least 6 months is generally necessary 2
• PSA values should be doubled for prostate cancer screening purposes in patients on finasteride 1
• Should not be combined with low-dose daily tadalafil as it offers no advantages in symptom improvement over either agent alone 3

Dosage for Androgenetic Alopecia

Recommended Dose

• 1 mg oral tablet once daily 3, 4
• This lower dose was specifically developed and approved for male pattern hair loss 4

Efficacy and Monitoring

• The 1 mg dose is effective for treating androgenetic alopecia 4
• Lowers serum PSA concentration by approximately 40-50% after 48 weeks of treatment 5
• The same PSA adjustment (doubling the value) recommended for men taking 5 mg finasteride should also apply to men taking the 1 mg preparation 5

Common Side Effects and Considerations

Sexual Side Effects

• Impotence: 8.1% in year 1, decreasing to 5.1% in years 2-4 2
• Decreased libido: 6.4% in year 1, decreasing to 2.6% in years 2-4 2
• Decreased volume of ejaculate: 3.7% in year 1, decreasing to 1.5% in years 2-4 2

Other Side Effects

• Gynecomastia (breast enlargement): 0.5% in year 1, increasing to 1.8% in years 2-4 2
• Breast tenderness: 0.4% in year 1, increasing to 0.7% in years 2-4 2

Common Pitfalls to Avoid

1. Not waiting long enough to assess efficacy (minimum 6 months for BPH symptoms) 2
2. Failing to adjust PSA values (should be doubled) when screening for prostate cancer 1, 5
3. Prescribing 5-ARIs for small prostates where they may not be as effective 1
4. Discontinuing therapy too early before maximum benefit is achieved 1
5. Combining with alpha blockers and low-dose daily tadalafil, which offers no additional benefit 3

Finasteride remains an effective treatment option for both BPH and androgenetic alopecia when used at the appropriate doses and with proper patient monitoring.