What is Finasteride used for?

Finasteride: Uses and Clinical Applications

Finasteride is primarily indicated for the treatment of symptomatic benign prostatic hyperplasia (BPH) in men with an enlarged prostate to improve symptoms, reduce the risk of acute urinary retention, and reduce the need for surgery. 1

Primary Indications

• Finasteride is FDA-approved for treatment of symptomatic BPH in men with an enlarged prostate (>30cc) 2, 1
• Finasteride can be used in combination with alpha-blockers (like doxazosin) to reduce the risk of symptomatic progression of BPH 1
• Finasteride at a lower dose (1 mg/day) is used for treatment of male pattern hair loss (androgenetic alopecia) 3, 4

Mechanism of Action

• Inhibits 5-alpha-reductase type II isoenzyme, reducing dihydrotestosterone (DHT) in the prostate by approximately 70% 2
• Leads to 15-25% reduction in prostate size within 6 months 2
• Increases peak urinary flow rate in men with BPH 2
• Decreases serum PSA levels by approximately 50% 2

Clinical Efficacy for BPH

• Patients experience an average 3-point improvement in the AUA Symptom Index, generally perceived as a meaningful change 2
• Long-term studies show symptom improvements maintained for 6-10 years 2
• Provides greater benefit in men with larger prostates and/or higher PSA values 2
• Reduces the risk of acute urinary retention and need for BPH-related surgery 1

Important Clinical Considerations

• Finasteride is ineffective for relief of lower urinary tract symptoms in patients without enlarged prostates 5, 2
• When screening for prostate cancer in men on finasteride, the measured PSA value should be doubled after 1 year of therapy 2
• Treatment duration should be at least 7 years if used for prostate cancer prevention 5
• Has a slower onset of action compared to alpha blockers; patients should be counseled that symptom improvement may take several months 2

Side Effects

• Sexual side effects are the most common adverse events:
  • Decreased libido (6.4% in first year, 2.6% in years 2-4) 2
  • Ejaculatory dysfunction (3.7% in first year, 1.5% in years 2-4) 2, 6
  • Erectile dysfunction (reported in some studies) 7
  • Gynecomastia (2.3-4.5% of patients) 5
• These side effects are typically reversible and become less common after the first year of therapy 2
• Some studies suggest potential neuropsychiatric effects due to changes in neuroactive steroid formation 8

Dosing Information

• For BPH: 5 mg daily 9
• For male pattern hair loss: 1 mg daily 3, 4
• The efficacy of the lower 1 mg dose for prostate cancer prevention is unknown 5

Clinical Pitfalls to Avoid

• Using finasteride in patients without prostatic enlargement is ineffective 5, 2
• Failure to adjust PSA interpretation (PSA levels decrease by approximately 50% after 12 months) 2
• Inadequate treatment duration - symptom improvement may take several months 2
• Finasteride is not FDA-approved for the prevention of prostate cancer 1