What medication can help shrink an enlarged prostate (Benign Prostatic Hyperplasia, BPH)?

Medications for Shrinking an Enlarged Prostate (BPH)

5-alpha reductase inhibitors (5-ARIs) such as finasteride and dutasteride are the most effective medications for physically shrinking an enlarged prostate, with dutasteride showing slightly better efficacy due to its dual inhibition of both type I and II 5-alpha reductase enzymes. 1

How 5-ARIs Work to Shrink the Prostate

5-ARIs work by:

• Inhibiting the conversion of testosterone to dihydrotestosterone (DHT) in prostate tissue
• Reducing DHT leads to prostate cell apoptosis (programmed cell death)
• Results in 15-25% reduction in prostate size after 6 months of treatment 1
• Maximum shrinkage effect typically achieved after 12 months of continuous therapy 2

Comparing Available 5-ARIs

Finasteride

• Selectively inhibits 5-AR type II isoenzyme
• Reduces serum DHT by approximately 70%
• Reduces prostate tissue DHT by approximately 80%
• FDA-approved for treatment of symptomatic BPH 3
• Typical dosage: 5 mg once daily 2

Dutasteride

• Inhibits both type I and II 5-AR isoenzymes
• Reduces serum DHT by approximately 95%
• Reduces prostate tissue DHT by approximately 94%
• Slightly more effective at reducing prostate volume than finasteride 1
• Typical dosage: 0.5 mg once daily 4

Patient Selection for 5-ARI Therapy

5-ARIs are most effective for:

• Men with demonstrable prostatic enlargement (>30cc volume) 1
• Men with PSA >1.5 ng/mL (indicating larger prostate size) 1
• Patients seeking to prevent disease progression rather than immediate symptom relief 1

5-ARIs are NOT appropriate for:

• Men with LUTS who do not have evidence of prostatic enlargement 1
• Patients seeking rapid symptom relief (alpha-blockers work faster) 1

Clinical Efficacy

• Average improvement of 3-4 points on AUA Symptom Index (clinically meaningful) 1
• Reduces risk of acute urinary retention by 67% (finasteride) 1
• Reduces need for BPH-related surgery by 64% (finasteride) 1
• Benefits increase with rising prostate volume or serum PSA 1

Important Monitoring Considerations

• 5-ARIs reduce serum PSA by approximately 50% after 12 months 5
• When screening for prostate cancer, PSA values should be doubled to accurately assess disease progression 1
• Treatment requires at least 6 months to evaluate effectiveness 2

Side Effects

Common side effects include:

• Decreased libido
• Ejaculatory dysfunction
• Erectile dysfunction 1, 5

These side effects are:

• Generally reversible upon discontinuation
• Less common after the first year of therapy 1
• May persist in some patients after stopping the medication (post-finasteride syndrome) 5

Combination Therapy

For patients with significant symptoms and enlarged prostates:

• Combination of an alpha-blocker (for rapid symptom relief) and a 5-ARI (for prostate shrinkage) is more effective than either medication alone for long-term management 1
• Combination therapy reduces:
  • Risk of symptomatic progression by 67%
  • Risk of acute urinary retention by 79%
  • Need for BPH-related surgery by 67% 1

Clinical Decision Making Algorithm

1. Confirm BPH diagnosis and assess prostate size (>30cc is ideal for 5-ARI therapy)
2. For patients with enlarged prostates seeking prostate shrinkage:
   • If rapid symptom relief is primary concern: Start with alpha-blocker
   • If long-term prostate shrinkage is primary concern: Start with 5-ARI
   • If both are concerns: Consider combination therapy
3. Choose between finasteride and dutasteride:
   • Dutasteride may provide slightly better prostate volume reduction
   • Both medications have similar side effect profiles 6
4. Counsel patient about:
   • Need for long-term therapy (minimum 6 months)
   • Potential sexual side effects
   • PSA monitoring implications

Remember that while alpha-blockers provide faster symptom relief, they do not actually shrink the prostate or modify disease progression like 5-ARIs do.