Mirabegron for Overactive Bladder: A Novel, First-in-Class B3- Agonist Therapy

Purpose: To discuss the pharmacotherapeutic aspects of Mirabegron which is a first-in- class novel B3 receptor agonist drug recently approved by the food and drug administra- tion (FDA) for the treatment of overactive bladder (OAB). Materials and Methods: We conducted a computerized search of the MEDLINE/PUB- MED databases with the word Mirabegron, B3 receptor agonist and overactive bladder. Results: Effect of Mirabegron on B3 adrenergic receptor purportedly releases nitric ox- ide (NO) by an increase in intracellular Ca2+ through accumulation of cyclic adenosine monophosphate (cAMP). Along with NO which relaxes the detrusor muscle, it also releases an urothelial-derived inhibiting factor (UDIF) that inhibits contractions. It in- creases the bladder capacity by causing bladder relaxation during the storage phase. Conclusion: Mirabegron appears to be a promising treatment in OAB patients by shift- ing its management from reducing detrusor over-activity to inducing relaxation. Also it lacks the troublesome side effects associated with the standard antimuscarinic manage- ment.