Traditionally, Overactive Bladder (OAB) symptoms are being treated mainly by anticholinergic medications. The side effect of anticholinergic medications (like dryness of mouth, constipation etc.) is one of the main reasons for their discontinuation. Recently, a new drug called Mirabegron is available for the treatment of OAB (J Urol. 2013 Apr;189(4):1388-95. doi: 10.1016/j.juro.2012.10.017. Epub 2012 Oct 16). Its mechanism of action is completely different from anticholinergic medications because it is β3-adrenoceptor agonist. A randomized, double blind, placebo controlled trial was conducted in USA and Canada in patients with symptoms of OAB for 3 months or more. They were randomized in placebo, 50 mg and 100 mg of Mirabegron once daily for 12 weeks. Primary end points were changes in number of incontinence episodes per 24 hours and micturitions per 24 hours and these were significantly less (p<0.05) in Mirabegron group. The incidence of side effects like dryness of mouth, constipation, hypertension, urinary infection etc were comparable to placebo. The Mirabegron was approved by US Food and Drug Administration (FDA) last year. In summary, this drug has same or better efficacy than placebo and older drugs and furthermore has almost no significant major side effects.
I hope Mirabegron will turn out to be a turning point for the OAB management and can confidently be prescribed in any group of patients without fear of significant side effects. The clinical data are strongly suggestive that it will be a wonderful drug. Hopefully, Mirabegron will be “that is it” for OAB treatment.