Dutasteride and Tamsulosin Combination Therapy for Benign Prostatic Hyperplasia
Combination therapy with dutasteride 0.5 mg and tamsulosin 0.4 mg daily is the recommended treatment regimen for men with moderate-to-severe BPH symptoms who have demonstrable prostatic enlargement (>30cc on imaging, PSA >1.5ng/mL, or palpable enlargement on digital rectal examination). 1, 2
Indications for Combination Therapy
- Combination therapy is FDA-approved for the treatment of symptomatic BPH in men with an enlarged prostate 3
- The combination targets different mechanisms: tamsulosin (alpha-blocker) provides rapid symptom relief while dutasteride (5α-reductase inhibitor) reduces prostate size over time 1, 2
- Most appropriate for men with moderate-to-severe LUTS (International Prostate Symptom Score >8) who have demonstrable prostatic enlargement (>30cc) 2
- Combination therapy significantly reduces the risk of BPH clinical progression by 67% compared to 39% for alpha-blockers and 34% for 5α-reductase inhibitors alone 2
Evidence for Efficacy
- The CombAT trial demonstrated that combination therapy provides significantly greater symptom improvement than either monotherapy alone after 2 years (primary endpoint) and 4 years of therapy 4, 5
- After 4 years, combination therapy significantly reduced the risk of acute urinary retention (AUR) or BPH-related surgery compared to tamsulosin monotherapy 5
- Meta-analysis confirms that combination therapy provides superior improvements in International Prostate Symptom Score, prostate volume, maximum urine flow rate, and post-void residual volume compared to tamsulosin alone 6
- Combination therapy improves both storage and voiding symptoms more effectively than either monotherapy 7
Dosing and Administration
- Recommended dosage: dutasteride 0.5 mg plus tamsulosin 0.4 mg, taken once daily 3
- Capsules should be swallowed whole and may be taken with or without food 3
- Treatment should be continued long-term for sustained benefits 1
Monitoring and Considerations
- Dutasteride reduces serum PSA levels by approximately 50% after 1 year of therapy; double the measured PSA value for accurate prostate cancer screening 2
- Expect rapid symptom improvement from tamsulosin component (days to weeks) with additional benefits from dutasteride developing over 3-6 months 2
- Monitor for symptom improvement using validated tools like IPSS 1
- Patients should not donate blood until 6 months after their last dose of dutasteride 3
Adverse Effects
- Common side effects include sexual dysfunction: erectile dysfunction (OR 2.24), ejaculation disorders (OR 3.37), and decreased libido (OR 2.25) 6
- Tamsulosin is associated with intraoperative floppy iris syndrome during cataract surgery; inform ophthalmologists before eye surgery 8
- Women who are pregnant or may become pregnant should not handle dutasteride capsules due to potential risk to male fetuses 3
Important Caveats
- Combination therapy should be reserved for patients with demonstrable prostatic enlargement, as this population benefits most from the addition of a 5-ARI 1, 2
- In men with very large prostates (≥58 mL), combination therapy may not provide significant additional benefit over dutasteride monotherapy 7
- Dutasteride is not approved for the prevention of prostate cancer 3
- Any confirmed increase in PSA while on dutasteride should be evaluated for potential prostate cancer, even if values remain within normal range for untreated men 3