AIMS: Mirabegron, the first β3 -adrenoceptor agonist to enter clinical practice, 
has a different mechanism of action from antimuscarinic agents. This review 
presents data on the efficacy, safety, and tolerability of mirabegron in studies 
conducted to date.
METHODS: All clinical data on mirabegron that are currently in the public domain 
are included, including some in-press manuscripts.
RESULTS: In Phase III clinical trials in patients with overactive bladder (OAB), 
mirabegron at daily doses of 25, 50, and 100 mg demonstrated significant 
efficacy in treating the symptoms of OAB, including micturition frequency, 
urgency incontinence, and urgency. Significant improvements in micturition 
frequency, urgency incontinence, and mean volume voided/micturition were seen as 
early as the first assessment (week 4) for mirabegron 50 and 100 mg, and were 
maintained throughout treatment. Responder analyses showed a significant 
improvement with mirabegron 50 and 100 mg in terms of dry rates, ≥50% reduction 
in mean number of incontinence episodes/24 hr, and the proportion of patients 
with ≤8 micturitions/24 hr at final visit. The benefit of mirabegron 50 and 
100 mg was also evident in patients ≥65 years of age, and in both 
treatment-naïve patients and those who previously discontinued antimuscarinic 
therapy. These data therefore demonstrate a clinically meaningful benefit with 
mirabegron in the objective endpoints of OAB. Assessment of measures of 
health-related quality of life and treatment satisfaction showed that patients 
perceived treatment with mirabegron as meaningful. In OAB clinical trials of up 
to 12 months mirabegron appeared to be well tolerated. The most common adverse 
events (AEs) observed with mirabegron in clinical trials of up to 12 months were 
hypertension, nasopharyngitis, and urinary tract infection. The incidence of dry 
mouth was similar to placebo, and was between three and fivefold less than for 
tolterodine extended release 4 mg. Since dry mouth is the most bothersome AE 
associated with antimuscarinic drugs and often a reason for treatment 
discontinuation, mirabegron may be a valuable treatment option for these 
patients.
CONCLUSIONS: In Phase III clinical trials, mirabegron at daily doses of 25, 50, 
and 100 mg demonstrated significant efficacy in treating symptoms of OAB and, at 
doses of 50 and 100 mg, demonstrated significant improvements versus placebo on 
key secondary endpoints, as early as the first assessment (week 4), and these 
were maintained throughout treatment. In OAB clinical trials of up to 12 months, 
mirabegron appeared to be well tolerated.