Therapeutic effectiveness and adverse drug reactions of mirabegron versus solifenacin in the treatment of overactive bladder syndrome.

INTRODUCTION: Overactive bladder (OAB) syndrome is a chronic disease characterized by urinary urgency with or without urge incontinence, frequency, and nocturia and antimuscarinic drugs such as solifenacin have been the mainstay of treatment. Mirabegron a beta 3 adrenoreceptor agonist has recently gained importance in the management of OAB. The rationale of the study is that mirabegron improves the storage function without affecting voiding which increases the therapeutic effectiveness. The objective was to determine the therapeutic effectiveness of mirabegron versus solifenacin.

METHODS: A prospective observational study was conducted on 298 patients with OAB syndrome attending the urology outpatient department of government medical college after obtaining institutional review board clearance. Patients of both genders, belonging to the 18-65 years of age group, attending the urology outpatient department were selected for the study. Patients were evaluated using the OAB-validated 8-question awareness tool (OAB-V8 score) before and after receiving drugs by direct questionnaire method after receiving informed consent. Patients were prescribed either solifenacin 5 mg or mirabegron 25 mg once daily by the urologist. Follow-up was done after 4 and 12 weeks. Adverse drug reactions of the drugs were assessed using the Central Drug Standard Control Organization suspected adverse reaction (ADR) form, and ADRs were notified to the nearest ADR monitoring center.

RESULTS: The mirabegron group showed maximum improvement in the mean OAB-V8 score values from baseline at 4 weeks (12.82 ± 5.86, P < 0.001) and 12 weeks (5.74 ± 3.31, P < 0.001) when compared to solifenacin. OAB-V8 scores of the solifenacin group also showed significant improvement from the baseline at 4 weeks (15.30 ± 5.54, P < 0.001) and 12 weeks (8.05 ± 4.59, P < 0.001). Heart rate, systolic, and diastolic blood pressures did not show significant changes during the follow-up in both the study groups. Thirteen patients developed ADRs such as dry mouth (four patients) and constipation (nine patients) in the solifenacin group. No ADRs were noted in the mirabegron group.

CONCLUSION: Mirabegron showed maximum improvement in the OAB-V8 scores in patients with OAB syndrome, although the solifenacin group also showed improvement. Adverse effects were less in the mirabegron group when compared to the solifenacin group.