Efficacy and safety of tolterodine in patients with detrusor instability: a dose-ranging study

To investigate the efficacy and safety of tolterodine, a new antimuscarinic agent, and define the optimum dosage in patients with symptoms of detrusor instability (urgency, increased frequency of micturition and/or urge incontinence).

A double-blind, placebo-controlled, multicentre study was carried out; after a 1-week run-in period to establish baseline values, 81 patients were randomized to receive placebo or tolterodine 0.5, 1, 2 or 4 mg twice daily for 2 weeks. Micturition (diary) variables, urodynamics and subjective urinary symptoms were assessed after 2 weeks' treatment.

A per-protocol analysis of efficacy in 64 patients showed dose-related improvements in recorded micturition and urodynamic variables, e.g. at a dosage of 2 mg twice daily, the frequency of micturition, episodes of incontinence and pad use were reduced by 20%, 46% and 29%, respectively, while the volume at first contraction increased by 89 mL. The 4 mg dosage was associated with a large increase in residual urinary volume and an increased incidence of dry mouth. The incidence of adverse events (mainly mild or moderate antimuscarinic effects) was comparable with placebo at tolterodine dosages of < or = 2 mg. No serious adverse events were observed and tolterodine had no clinically significant impact on electrocardiographic or laboratory findings.

The results indicate that tolterodine offers an effective treatment for the symptoms of detrusor instability. The optimum dosage appears to be 1-2 mg twice daily.