Objective: To compare the efficacy and tolerability of extended-release formulations of oxybutynin chloride and tolterodine tartrate in women with overactive bladder.
Patients and methods: The OPERA (Overactive bladder: Performance of Extended Release Agents) trial was a randomized, double-blind, active-control study performed at 71 US study centers from November 21, 2000, to October 18,2001. Extended-release formulations of oxybutynin at 10 mg/d or tolterodine at 4 mg/d were given for 12 weeks to women with 21 to 60 urge urinary incontinence (UUI) episodes per week and an average of 10 or more voids per 24 hours. Episodes of UUI (primary end point), total (urge and nonurge) incontinence, and micturition were recorded in 24-hour urinary diaries at baseline and at weeks 2, 4, 8, and 12 and compared. Adverse events were also evaluated.
Results: Improvements in weekly UUI episodes were similar for the 790 women who received extended-release formulations of oxybutynin (n = 391) or tolterodine (n = 399). Oxybutynin was significantly more effective than tolterodine in reducing micturition frequency (P = .003), and 23.0% of women taking oxybutynin reported no episodes of urinary incontinence compared with 16.8% of women taking tolterodine (P = .03). Dry mouth, usually mild, was more common with oxybutynin (P = .02). Adverse events were generally mild and occurred at low rates, with both groups having similar discontinuation of treatment due to adverse events.
Conclusions: Reductions in weekly UUI and total incontinence episodes were similar with extended-release formulations of oxybutynin and tolterodine. In the oxybutynin group, micturition frequency was significantly lower, and the percentage of women reporting no urinary incontinence episodes was significantly higher compared with the tolterodine group. Dry mouth was more common with oxybutynin, but tolerability was otherwise comparable, including adverse events involving the central nervous system.