This analysis reviews clinical trials of the efficacy and safety of
tolterodine for use in
overactive bladder. It also compares the safety and efficacy of
tolterodine and previously available
pharmacotherapy. The MEDLINE database (1966 to present) was searched for all English language randomized controlled trials with keyword
tolterodine. The search retrieved 10 randomized controlled trials involving
tolterodine. Studies ranged from 2 to 12 weeks in duration. Nine trials studied
tolterodine vs. placebo, 6 compared
tolterodine vs.
oxybutynin, 6 compared different doses of
tolterodine, and 1 compared immediate-release and extended-release
tolterodine. Doses of
tolterodine were 0.5-4 mg bid or 4 mg extended-release daily, and doses of
oxybutynin were 5 mg bid or tid. All studies found a benefit of
tolterodine over placebo in decreasing symptoms of
overactive bladder. Parameters significantly improved by
tolterodine include number of voids per day, urine volume per void, number of incontinent episodes per day, pad use, maximal cystometric capacity, residual volume, volume at first detrusor contraction, and volume at normal desire to void.
Tolterodine 2 mg bid was consistently of equal efficacy as
oxybutynin 5 mg tid. Adverse events with both medications were mostly dose-related autonomic nervous system events. The most common adverse event was dry mouth, which was both more frequent and more severe with
oxybutynin 5 mg tid than with
tolterodine 2 mg bid. Dry mouth did not generally result in discontinuation of medication with either
drug. Most
drug withdrawal was because of blurred vision or
headache.
Tolterodine 2 mg bid caused less
dose reduction, patient withdrawal, and adverse events, especially dry mouth, compared with
oxybutynin 5 mg tid. A single trial found
tolterodine extended-release 4 mg/day to have improved efficacy for decreasing
urge incontinence episodes along with lower frequency of dry mouth vs. immediate-release
tolterodine 2 mg bid. At 4 mg bid,
tolterodine caused
urinary retention. Neither
drug significantly altered any laboratory tests, nor was there clear evidence of electrocardiographic abnormalities induced by either
drug. In all randomized controlled trials to date,
tolterodine 2 mg bid is an equally effective alternative to
oxybutynin 5 mg tid, while causing less intense and less frequent dry mouth or need for treatment withdrawal.