Doctors commonly prescribe the drugs dutasteride (Avodart) and tamsulosin (Flomax) for the treatment of an enlarged prostate and the moderate-to-severe urinary symptoms that accompany BPH (benign prostatic hyperplasia). But because the drugs work differently, researchers hypothesized that taking both might be more effective at controlling symptoms than taking just one. The CombAT trial, a four-year randomized, double-blind study of 4,844 men diagnosed with BPH, was launched to test that hypothesis. Each participant was randomly assigned to receive a daily combination of dutasteride and tamsulosin, dutasteride and a placebo, or tamsulosin and a placebo.
After following the participants for two years, the researchers found that taking the drug combination resulted in significantly greater improvements in symptoms, such as improved urinary flow, than taking either drug alone — so-called monotherapy. However, men who took both drugs experienced more side effects than the men taking one drug; in most cases, the side effects were minor and didn’t cause the men to stop the medication.
A second report noted that the drug combination also resulted in significant improvements in quality of life and satisfaction with treatment over monotherapy. To assess quality of life and treatment satisfaction, participants responded to questionnaires every three months that asked about the strength of the urinary stream, pain upon urination, physical discomfort, worries about health, and changes in daily activities.
The CombAT trial mimics an earlier study, which showed that the combination of finasteride (Proscar) and doxazosin (Cardura) was more effective at easing BPH than either drug alone.
SOURCES: Barkin J, Roehrborn CG, Siami P, et al. Effect of Dutasteride, Tamsulosin and the Combination on Patient-Report Quality of Life and Treatment Satisfaction in Men with Moderate-to-Severe Benign Prostatic Hyperplasia: 2-Year Data from the CombAT Trial. BJU International 2009;103:919–26. PMID: 19239460.
Roehrborn CG, Siami P, Barkin J, et al. The Effects of Dutasteride, Tamsulosin and Combination Therapy on Lower Urinary Tract Symptoms in Men with Benign Prostatic Hyperplasia and Prostatic Enlargement: 2-Year Results from the CombAT Study. Journal of Urology 2008;179:616–21. PMID: 18082216.
Originally published Oct. 1, 2009; Last reviewed April 18, 2011