Efficacy and safety of extended-release oxybutynin in combination with tamsulosin for treatment of lower urinary tract symptoms in men: randomized, double-blind, placebo-controlled study

Abstract

Objective: To evaluate the efficacy and tolerability of extended-release oxybutynin in combination with the alpha1-blocker tamsulosin in reducing lower urinary tract symptoms in men.

Patients and methods: In this multicenter, double-blind trial performed between March 29, 2004, and June 22, 2005, 420 men aged 45 years or older with a total International Prostate Symptom Score (IPSS) of 13 or more and IPSS for storage of 8 or more were randomized to receive tamsulosin (0.4 mg/d) with either extended-release oxybutynin (10 mg/d) or placebo for 12 weeks. Eligibility requirements included a maximum flow rate of 8 mL/s or more with voided volume of 125 mL or more and a postvoid residual volume of 150 mL or less on 2 occasions. Postvoid residual volume and peak flow rates at weeks 4, 8, and 12 were measured. The primary end point was change from baseline in total IPSS after 12 weeks of treatment. Secondary outcomes included change in IPSSs for storage and quality of life.

Results: Tamsulosin combined with extended-release oxybutynin resulted in significantly greater improvement in total IPSS compared with tamsulosin and placebo after 8 (P=.03) and 12 (P=.006) weeks of treatment, and improved IPSS for storage and quality of life at all assessment points (P<.01). The incidence of postvoid residual volume higher than 300 mL was 2.9% (6/209) in patients receiving combination therapy compared with 0.5% (1/209) in patients receiving tamsulosin alone (P=.12). Occurrence of peak flow rates below 5 mL/s was 3.8% (8/209) for combination therapy and 5.7% (12/209) for tamsulosin alone (P=.49).

Conclusion: In men with substantial storage symptoms, combination therapy with tamsulosin and extended-release oxybutynin demonstrated greater efficacy than and comparable safety and tolerability to tamsulosin monotherapy.