NEW YORK (Reuters Health) – In the treatment of lower urinary tract symptoms in men, extended-release oxybutynin plus tamsulosin is more effective than tamsulosin alone and just as safe and tolerable, new research suggests.

As reported in the September issue of the Mayo Clinic Proceedings, Dr. Scott A. MacDiarmid, from Alliance Urology Specialists in Greensboro, North Carolina, and colleagues assessed the outcomes of 420 men who were taking tamsulosin (0.4 mg/d) and were randomized to receive extended-release oxybutynin (10 mg/d) or placebo for 12 weeks.

The subjects were at least 45 years of age. They had a total International Prostate Symptom Score (IPSS) of 13 or more out of a possible total of 35, and a score of 8 or more out of a possible total of 15 on the urine storage component of the IPSS. Other eligibility criteria included a maximum flow rate of at least 8 mL/s with voided volume of at least 125 mL, and a postvoid residual volume of 150 mL or less on two occasions, the report indicates.

At 12 weeks, combination therapy improved the total and storage IPSS scores to a significantly greater extent than did tamsulosin monotherapy. Specifically, the decrease in the total IPSS score was 6.9 for combination therapy and 5.2 with tamsulosin alone; corresponding decreases in the IPSS storage score were 3.7 and 2.4.

From the safety angle, 2.9% of combination therapy patients and 0.5% of those given tamsulosin alone had postvoid residual volumes more than 300 mL, a nonsignificant difference. The corresponding percentages with peak flow rates below 5 mL/s were 3.8% and 5.7%, also not a statistically significant difference.

Both treatment regimens were well tolerated and the percentage of patients with side effects in each was identical, 42.6%. Patients treated with combination therapy were more likely than those given tamsulosin alone to report dry mouth: 15.3% vs. 4.8% (p < 0.001). “Although our results indicate the safety of extended-release oxybutynin as an adjunct to tamsulosin during the study period in this population of men with lower urinary tract symptoms, additional studies assessing the long-term safety of this regimen should be conducted,” the authors state. Reference:
Mayo Clin Proc 2008;83:1002-1010.