What are the indications for starting dutasteride (Avodart) in men with benign prostatic hyperplasia (BPH)?

Indications for Starting Dutasteride in BPH

Dutasteride is 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 risk of BPH-related surgery. 1

Primary Indications

• Enlarged prostate (>30cc) - Dutasteride is particularly effective for men with prostate enlargement 2
• Moderate to severe symptomatic BPH - For patients experiencing bothersome lower urinary tract symptoms 1
• Risk reduction - To decrease the risk of:
  • Acute urinary retention (67% reduction) 2
  • BPH-related surgery (64% reduction) 2

Mechanism and Efficacy

Dutasteride is a dual 5-alpha reductase inhibitor (5-ARI) that:

• Inhibits both type 1 and type 2 5-alpha reductase enzymes 3
• Reduces serum DHT by approximately 95% and prostate tissue DHT by approximately 94% 2
• Decreases prostate volume by up to 26% after 4 years of treatment 4
• Improves urinary symptoms after approximately 6 months of therapy 4

Monotherapy vs. Combination Therapy

• Monotherapy - Dutasteride 0.5mg daily is effective as standalone treatment for men with enlarged prostates and moderate-to-severe symptoms 1
• Combination therapy - Dutasteride in combination with the alpha-adrenergic antagonist tamsulosin is indicated for men with symptomatic BPH and an enlarged prostate 1
  • Combination therapy is superior to either drug as monotherapy in improving BPH-related symptoms and peak urinary flow 5
  • Consider combination therapy for more rapid symptom relief while maintaining long-term benefits of dutasteride 2

Clinical Decision Points

• Prostate size - Most beneficial in men with prostate volume >30cc 2
• Symptom severity - Indicated for moderate to severe symptoms 1
• PSA levels - Men with higher PSA levels (≥1.5 ng/mL) are at greater risk of BPH progression and may benefit more from dutasteride therapy 5
• Risk of progression - Consider in asymptomatic men with larger prostates (>40mL) to prevent clinical progression of BPH 6

Comparative Efficacy

• Dutasteride and finasteride are similarly effective in reducing prostate volume, improving urinary flow rate (Qmax), and relieving urinary symptoms associated with BPH 7
• The dual inhibition of both 5-AR isoenzymes by dutasteride (vs. finasteride's type 2 specificity) provides more complete suppression of DHT 3

Important Considerations

• Onset of action - Symptom improvement typically begins after 3-6 months of treatment 2
• PSA monitoring - PSA levels should be doubled for interpretation in men taking dutasteride 2
• Limitations - Dutasteride is not approved for the prevention of prostate cancer 1
• Side effects - Sexual dysfunction (reduced libido, impotence, and gynecomastia) may occur but are generally well-tolerated 4

Prevention in High-Risk Asymptomatic Men

For asymptomatic men with enlarged prostates (>40mL), dutasteride can:

• Reduce clinical progression of BPH by 41% (relative risk reduction) 6
• Provide an absolute risk reduction of 15% with a number needed to treat of 7 6
• Significantly reduce the risk of acute urinary retention and BPH-related surgery 6