Feasibility of mirabegron in the treatment of overactive bladder in patients affected by Parkinson's disease: A pilot study

Background: We investigated the effectiveness and safety of mirabegron oral treatment in a group of patients with Parkinson's disease (PD) and overactive bladder (OAB), refractory to antimuscarinics. Materials and methods: Thirty patients with PD and refractory OAB were prospectively included in the study. At baseline, motor symptoms, severity of disease and cognitive status were assessed with the Hoehn-Yahr Scale, the Unified Parkinson's disease Rating Scale, the Mini Mental State examination and the Montreal Cognitive Assessment. At baseline, urinary symptoms, satisfaction with treatment and the impact of urinary incontinence on quality of life (QoL) were assessed with the 3-day voiding diary, the Visual Analogue Scale (VAS), the Incontinence-QoL questionnaire and urodynamics. Patients started assuming mirabegron 50 mg tablets once daily. Evaluation of urinary symptoms and related questionnaires, motor symptoms, severity of PD and uroflowmetry with postvoid residual volume measurement were then repeated at the 3- and 6-month follow up. Side effects were also noted. Results: At baseline, the most frequently reported urinary symptoms were: urinary urgency (present in all the patients), urge urinary incontinence in 28/30 (93.3%) and increased daytime urinary frequency in 25 (83.3%) patients. At the 3-month follow up, 7 out of the 30 patients achieved a complete urinary continence. Significant improvements in VAS and Incontinence-QoL scores were observed in 24 patients. These benefits were maintained for the whole observation period. Four patients discontinued treatment due to poor efficacy, and two due to the cost of the drug. Conclusions: Mirabegron is a safe and effective treatment in patients with PD and OAB refractory to anticholinergics in the short-term follow up.