Comparative Efficacy and Tolerability of Antimuscarinic Agents and the Selective β3-Adrenoceptor Agonist, Mirabegron, for the Treatment of Overactive Bladder: Which is More Preferable as an Initial Treatment?

The objective of the present study was to evaluate comparative efficacy and tolerability of antimuscarinics and mirabegron as primary and salvage therapy in patients with overactive bladder (OAB).

Patients ≥50 years with OAB symptoms were enrolled. Patients were initially treated with antimuscrinics or mirabegron for 8 weeks. When patients were refractory or intolerant to an initial treatment, drugs were switched to the other. The initial and second-line efficacy was assessed at baseline, 4 and 8 weeks after the treatment having the following parameters of the International Prostatic Symptom Score (IPSS), quality of life (QOL) index, Overactive Bladder Symptom Score (OABSS) and post-void residual (PVR) urine volume. Dry mouth and constipation were evaluated using dry mouth scale and constipation assessment scale, respectively.

A total of 117 patients were enrolled. As an initial treatment, 60 patients were given antimuscarinics and 57 patients received mirabegron. Similar initial treatment efficacy was observed between the two drugs in the whole patients. However, mirabegron was more efficacious to men with OAB unresponsive to prior α1-blocker. Dry mouth and constipation were less burdensome in patients treated with mirabegron. Such differences in efficacy and tolerability were associated with significantly greater persistence of mirabegron. As a second-line setting, both drugs appear to be equally effective at least to relieve urgency symptoms remaining after an initial therapy.

The present study suggests that mirabegron seems to have priority as an initial therapy with a distinct efficacy/tolerability balance. Mirabegron also represents a reasonable alternative to antimuscarinics for patients who had insufficient efficacy and poor tolerability.

Lower urinary tract symptoms. 2016 Dec 23 [Epub ahead of print]

Minoru Kobayashi, Akinori Nukui, Takao Kamai

Department of Urology, Utsunomiya Memorial Hospital, Utsunomiya, Japan., Department of Urology, Nasu Red Cross Hospital, Ohtawara, Japan., Department of Urology, Dokkyo Medical University, Mibu, Japan.