Combination Therapy for Symptomatic Benign Prostatic Hyperplasia

Evidence for Combination Therapy

Combination therapy with tamsulosin and dutasteride is a well-established treatment approach for BPH, targeting different sites in the lower urinary tract 1
The American Urological Association strongly recommends 5-ARI in combination with an alpha blocker for patients with LUTS associated with demonstrable prostatic enlargement (prostate volume >30cc on imaging, PSA >1.5ng/mL, or palpable prostate enlargement on digital rectal examination) 1
Two major studies, Medical Therapy of Prostatic Symptoms (MTOPS) and Combination of Avodart and Tamsulosin (CombAT), showed statistically significant reductions in parameters of clinical progression with combination approaches over monotherapy 2

Determine prostate size (>30cc on imaging, PSA >1.5ng/mL, or palpable enlargement on DRE) and assess symptom severity using validated tools like IPSS 1, 2
For patients with moderate-to-severe LUTS and enlarged prostate: combination therapy is appropriate 1
For patients on dutasteride, double the measured PSA value after 1 year of therapy to accurately gauge disease progression 4

Combination therapy should be reserved for patients with demonstrable prostatic enlargement, as this population benefits most from the addition of a 5-ARI 1
The onset of action differs between medications - alpha blockers like tamsulosin provide relatively rapid symptom relief, while 5-ARIs like dutasteride have a slower onset but provide long-term benefits in reducing prostate size and disease progression 4
Dutasteride reduces serum PSA levels by approximately 50%, which should be considered when screening for prostate cancer 4
Tamsulosin is associated with intraoperative floppy iris syndrome during cataract surgery, which should be considered if ophthalmic procedures are planned 3