The FDA has approved mirabegron for the treatment of overactive bladder (OAB) with symptoms of urge urinary incontinence, urgency, and urinary frequency. The drug, marketed by Astellas Pharma Inc. under the trade name Myrbetriq, is the first oral OAB medication with a distinct mechanism of action since the debut of anticholinergic drugs 30 years ago.
Mirabegron is an oral beta-3 adrenergic agonist taken once daily. It has been studied in more than 10,000 patients over 10 years.
Mirabegron works by relaxing the detrusor smooth muscle during the storage phase of the urinary bladder fill-void cycle by activation of beta-3 adrenergic receptors, which increases bladder capacity. Antimuscarinics, which are a standard treatment for OAB, work by binding to muscarinic receptors in the bladder and inhibiting involuntary bladder contractions.
“OAB impacts each individual differently so it is important to have a variety of treatment options available,” said Victor Nitti, MD, Professor of Urology and Director of Female Pelvic Medicine and Reconstructive Surgery at New York University Langone Medical Center.
The recommended starting dose for mirabegron is 25 mg once daily with or without food. Mirabegron 25 mg is effective within eight weeks. Based on individual efficacy and tolerability, the dose may be increased to 50 mg once daily.