Myrbetriq (mirabegron) and Toviaz (fesoterodine fumarate) are used to treat overactive bladder (OAB) with symptoms of urge urinary incontinence, urgency, and urinary frequency. Myrbetriq and Toviaz belong to different drug classes. Myrbetriq is a beta-3 adrenergic agonist and Toviaz is a muscarinic receptor antagonist.