Mirabegron

Mirabegron, a compound with multiple functional groups, is the active ingredient of drugs used for treating an overactive bladder. It is sold under the trade names Myrbetriq and Betmiga, both marketed by Astellas Pharma (Tokyo).

Mirabegron activates the β₃ adrenergic receptor in the detrusor muscle of the bladder. Activating the receptor relaxes the muscle, allowing the bladder to accommodate a greater quantity of urine.

The drug, however, is not without adverse side effects. The most common is elevated blood pressure; but there are many others, including dry mouth, susceptibility to colds, and urinary tract infection.

Although mirabegron is taken orally, one of the hazards listed in its safety data sheets (see hazard information box) is oral toxicity. But the medicine is not toxic unless the patient consumes 5–10 times the normally prescribed dosage.