Use of mirabegron in treating overactive bladder

The lack of an alternative to antimuscarinics has led to the search for new drug targets for overactive bladder (OAB) symptoms. The presence of beta-3 adrenoreceptors in the bladder has been confirmed, and they are known to have a role in bladder relaxation. Targeting these receptors improves bladder compliance on filling and increases bladder capacity. MEDLINE literature search on efficacy and safety of mirabegron was performed. The US Food and Drug Administration Web site, clinicaltrials.gov, and controlled-trials.com online trial registries were searched for English-language articles containing the term mirabegron. Finally, abstracts from recent International scientific meetings were searched for randomised controlled trials (RCTs). Studies show that mirabegron reduces the number of micturitions and incontinence episodes in a 24-h period compared with placebo. Dry mouth and gastrointestinal disturbances are the most common side effects, but these have been rated as mild to moderate. A small rise in mean heart rate and blood pressure has been shown. Further investigations are ongoing and results are awaited. Although mirabegron is metabolised by CYP2D6, it is also thought to inhibit the activity of this enzyme. Therefore, potential drug interactions with other CYP2D6 substrates need to be further studied. Mirabegron is a promising alternative to antimuscarinics. Further information on its long-term use in terms of efficacy, safety, and tolerability is awaited.