An Expert Report on Mirabegron (DB08893): A Comprehensive Monograph

1.0 Executive Summary

Mirabegron (DrugBank ID: DB08893) is a first-in-class, orally active, selective beta-3 adrenergic receptor (β3-AR) agonist. It represents a significant therapeutic advancement in the management of urological storage disorders, offering a distinct mechanism of action compared to the long-standing class of antimuscarinic agents. Developed by Astellas Pharma and marketed under brand names including Myrbetriq®, Betmiga®, and Betanis®, Mirabegron is indicated for the treatment of overactive bladder (OAB) in adults with symptoms of urge urinary incontinence, urgency, and urinary frequency. Its approval has been extended to include treatment of neurogenic detrusor overactivity (NDO) in pediatric patients and for use in combination with the antimuscarinic solifenacin succinate for refractory OAB in adults.[1]

The primary pharmacodynamic effect of Mirabegron is the relaxation of the detrusor smooth muscle during the bladder's storage phase. This is achieved through selective activation of β3-ARs, which are highly expressed in the bladder, leading to an increase in intracellular cyclic adenosine monophosphate (cAMP).[4] This mechanism increases the functional capacity of the bladder, thereby alleviating the core symptoms of OAB. Crucially, Mirabegron lacks significant antimuscarinic activity, which is the pharmacological basis for its principal clinical advantage: a more favorable tolerability profile than traditional anticholinergic drugs, with a markedly lower incidence of dry mouth and constipation.[1]