A Comparative Study on the effectiveness and Tolerability of Mirabegron and Antimuscarinics in the treatment of Overactive bladder

Abstract

Background: Despite antimuscarinic treatment options being available as the first line agents for overactive bladder (OAB), there is still a need for distinct treatment approaches to manage its suboptimal response and noncompliance. Mirabegron, a β3-adrenoceptor agonist, could be a better alternative to antimuscarinics in OAB treatment with a good effectiveness/tolerability balance. Aim: To compare the clinical profile of mirabegron and antimuscarinics in the treatment of overactive bladder. Method: A prospective, observational study was conducted in two groups of patients who received either mirabegron (n=120) or antimuscarinics (n=120) for the treatment of OAB. Effectiveness of the drugs were assessed at baseline, 4 and 8 weeks after the treatment using the Overactive Bladder Symptom Score (OABSS) and International Prostatic Symptom Score (IPSS) questionnaires. The safety assessment was done by measuring the post-void residual (PVR) urine volume and assessing the adverse drug reactions (ADR). The probability and severity of the ADRs were measured using Naranjo scale and Hartwig’s scale respectively. Also a subgroup analysis was carried out to compare the effectiveness of the two drugs in patients with OAB related to benign prostatic hyperplasia (BPH). Results: The overall effectiveness of antimuscarinics and mirabegron was found to be similar, but mirabegron showed better reduction in the daytime frequency (p=0.049). They also differ in safety profile with the overall incidence of adverse events being significantly higher in antimuscarinics group (15.83%) (19/120) than in the mirabegron group group (1.7%) (2/120) (p<0.001). In the patients with OAB related to BPH also, there was a better reduction in the daytime frequency with mirabegron than with antimuscarinics, with overall effectiveness between groups being similar. In addition, mirabegron did not worsen the voiding symptoms and was found to be a better combination with alpha1 blockers than the antimuscarinics in patients with OAB related to BPH. No significant change was there in the PVR values within and between the groups. Conclusion: Mirabegron is a better alternative to antimuscarinics in the treatment of OAB with a distinct effectiveness/tolerability balance especially in patients with OAB related to BPH.