ObjectivesTo evaluate the efficacy and safety of mirabegron compared with imidafenacin for the treatment of female patients with overactive bladder. MethodsPatients (n = 89) were randomized to receive 0.1 mg imidafenacin twice daily (n = 47) or 50 mg mirabegron once daily (n = 42) for 12 weeks. The primary efficacy end-point was change in total Overactive Bladder Symptom Score. Secondary efficacy end-points included change in Overactive Bladder Symptom Score, 3-day micturition diary, International Prostate Symptom Score and Overactive Bladder Questionnaire. Safety assessments included adverse events, vital signs, post-void residual volume and patient-reported incidence, and severity of distinctive symptoms related to adverse events. ResultsThe mirabegron group showed a significantly reduced mean total Overactive Bladder Symptom Score from baseline, but no significant differences were noted in change of total Overactive Bladder Symptom Score compared with the imidafenacin group. Significant improvements in secondary efficacy end-points were observed regarding the mean number of micturitions/24 h, mean number of urgency episodes/24 h, mean number of incontinence episodes/24 h, mean volume voided/micturition, total International Prostate Symptom Score and quality of life in both groups, with no significant differences between the groups. The overall incidence of adverse events and the incidence of dry mouth were significantly higher in the imidafenacin group than in the mirabegron group. Patient-reported incidence and the severity of dry mouth were significantly exacerbated in the imidafenacin group. ConclusionsTreatment with 50 mg mirabegron once daily effectively relieves overactive bladder symptoms in women with fewer adverse events than treatment with antimuscarinics.