Objectives: To evaluate the dose-response relationship and safety/tolerability of solifenacin succinate (YM905) in the treatment of overactive bladder (OAB), and to compare its efficacy and safety/tolerability with tolterodine 2 mg twice daily.
Patients and methods: This multicentre study included a 2-week single-blind placebo run-in, a 4-week double-blind placebo-controlled active treatment phase, and a 2-week follow-up. Men and women with an OAB and urodynamic evidence of detrusor overactivity were randomized to placebo or solifenacin 2.5, 5, 10 or 20 mg once daily, or tolterodine 2 mg twice daily.
Results: Of 265 patients enrolled, 225 were randomized and 192 completed the study. Solifenacin 5, 10 and 20 mg produced statistically significant (P < 0.05) improvements in voids/24 h vs placebo, whereas tolterodine did not; the mean change with tolterodine was between those with solifenacin 2.5 and 5 mg. The outcome was similar for the mean change from baseline to endpoint in mean volume voided/void. For incontinence and urgency episodes/24 h the solifenacin dose groups showed numerically superior changes vs placebo; the mean effects with tolterodine were generally smaller than with solifenacin. Most of the efficacy effect of solifenacin was evident at 2 weeks. Quality-of-life outcomes supported the efficacy results. Solifenacin 5 and 10 mg were well tolerated; there were no serious treatment-related adverse events. The incidence of dry mouth was 14% for solifenacin 5 and 10 mg, 2.6% for placebo and 24% for tolterodine.
Conclusion: In this study, the 5- and 10-mg doses of solifenacin appeared to be the most clinically effective for treating OAB, considering the balance between efficacy, quality of life and tolerability. From the results of this study solifenacin 5 and 10 mg were selected for further evaluation in large-scale phase 3 studies.