Mirabegron, is the only β-3 adrenoreceptor (AR) agonist available for the treatment of
overactive bladder (OAB). To assess the efficacy and tolerability of this novel
drug therapy, two phase II and six phase III Astellas-sponsored trials have been conducted with over 10,500 adults with OAB recruited. Of these, seven were randomized, double blind, 12-week placebo controlled studies and the other was for 12 months and not placebo controlled. The evidence described would suggest that
mirabegron is as efficacious as most
antimuscarinics, including
tolterodine extended release (ER) 4 mg, compared with placebo with regard to objective measures such as reduction in number of voids per 24 hours, mean volume per void, mean number of episodes of general
urinary incontinence, urgency
urinary incontinence and urgency per 24 hours; and subjective measures such as severity of urgency, patient perception of bladder condition and validated continence quality of life questionnaires. Regarding tolerability, these data would suggest that patients taking
mirabegron suffer a similar rate of adverse effects as those taking placebo alone, whereas the rate in those taking
antimuscarinics is greater. Thus
mirabegron presents a safe and effective alternative treatment to
antimuscarinics for patients with OAB symptoms. Patients who may particularly benefit from
mirabegron include those who are unsuitable for
antimuscarinics or who have previously struggled with
antimuscarinic side effects.