Clinical Question: Is extended-release oxybutynin or tolterodine more effective and tolerable for women with an overactive bladder?

Setting: Outpatient (specialty)

Study Design: Randomized controlled trial (double-blinded)

Synopsis: Overactive bladder is characterized by symptoms of urinary urgency and frequent micturitions with or without involuntary loss of urine (urge urinary incontinence). This study was conducted in 71 centers in the United States. Investigators enrolled 790 women with 21 to 60 episodes of urge urninary incontinence per week and who urinated 10 or more times per day. Almost one half of the women had been treated previously with an anticholinergic. The study did not include a placebo control arm, and allocation concealment was not documented.

The women were randomly assigned to receive extended-release oxybutynin in a dosage of 10 mg per day or extended-release tolterodine in a dosage of 4 mg per day for three months. The women kept 24-hour diaries for seven days at baseline and during weeks 2, 4, 8, and 12 of treatment.

The average number of weekly episodes of urge urinary incontinence did not differ between the two groups, decreasing from approximately 37 episodes to 11 per week in each group. The average number of total episodes of incontinence also was similar between the two groups, decreasing from approximately 43 episodes to 13 per week. More women treated with oxybutynin reported no episodes of incontinence in their last week of treatment (23 versus 16.8 percent; number needed to treat = 16). Dry mouth was reported by 29.7 percent of women receiving oxybutynin and 22.3 percent of those receiving tolterodine, although most episodes were characterized as mild.

Bottom Line: After three months of treatment, approximately one in four women receiving extended-release oxybutynin and one in six women receiving extended-release tolterodine were completely continent. Overall, both drugs similarly decreased the average number of episodes of urge urinary incontinence and total incontinence. More women reported dry mouth while taking oxybutynin. These results are similar to those seen with immediate-release forms of both drugs. (Level of Evidence: 1c)