Tolterodine: A clinical review

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.