The efficacy and tolerability of tarafenacin, a new muscarinic acetylcholine receptor M3 antagonist in patients with overactive bladder; Randomised, double-blind, placebo-controlled phase 2 study

Objectives To evaluate the dose-response relationship of tarafenacin, an antimuscarinic agent in development phase, for efficacy and safety, at daily doses of 0.2 and 0.4 mg for the treatment of overactive bladder (OAB) Patients and methods This multicentre, placebo-controlled, randomised, double-blind, phase 2b study was conducted. Patients were randomised to tarafenacin 0.2 mg, tarafenacin 0.4 mg or placebo daily for 12 weeks. Adult patients with OAB for at least 6 months, with an average of ≥ 8 micturitions per day and ≥ 3 incontinence episodes or a total of ≥ 6 urgency episodes per 3 days were enrolled. The primary objective was to compare the mean changes in the number of micturitions per 24 h of the two doses of tarafenacin compared with placebo from baseline to 12 weeks after treatment. Results A total of 334 patients were screened, of whom 235 patients were randomised. The mean decrease in the number of micturitions per 24 h from baseline to 12 weeks was statistically higher in the tarafenacin 0.4 mg group (-2.43 ± 2.21 times per day, p = 0.033) and non-statistically significant in the tarafenacin 0.2 mg group (-1.92 ± 2.45 times per day, p = 0.393) when compared with the placebo group (-1.77 ± 2.95 times per day). There were no statistically significant differences in the mean change of urgency episodes per 24 h among three groups. The most common adverse event was dry mouth. There were no significant differences in blurred vision and constipation compared with placebo. Conclusions Tarafenacin 0.4 mg decreased the number of micturitions in patients with OAB after 12 weeks compared with placebo, and the dose-response relationship of tarafenacin 0.2 and 0.4 mg was confirmed. Both dose levels of tarafenacin were well tolerated.