A double-blind randomized dose-response study comparing daily doses of 5, 10 and 15 mg controlled-release oxybutynin: balancing efficacy with severity of dry mouth

Objective To assess the efficacy, incidence of dry mouth and overall satisfaction with initial doses of 5, 10 and 15 mg of a new, once-daily, controlled-release (CR) form of oxybutynin for treating urge urinary incontinence (UUI). Patients and Methods Patients who reported urinary incontinence (UI) (one or more episodes/diary) and voiding frequency (eight or more voids/day) or urgency (one or more episodes/diary) during a 2-week baseline were randomized to once-daily 5, 10 or 15 mg CR oxybutynin for 4 weeks. Daily episodes of UI, voids, urgency, adverse events, dry mouth and satisfaction were recorded in a 3-day diary at baseline and after 4 weeks of treatment. In all, 237 patients were randomized and evaluated. Results Episodes of UI, voids and urgency were significantly reduced over the study period at all doses. Daily UI episodes were significantly lower with 15 mg/day than 5 and 10 mg/day. Dry mouth symptoms were similar in the 10 and 15 mg/day groups, and higher than in the 5 mg/day group. However, significantly greater overall satisfaction was reported with 15 than 5 mg/day. Conclusions There were significant dose-response relationships with CR oxybutynin for both UI episodes and dry mouth. The greatest satisfaction was with 15 mg/day, and the severity of dry mouth was comparable at 10 mg/day, indicating that greater efficacy at the higher dose did not compromise tolerability.