Mirabegron: A first-in-class beta-3 agonist for overactive bladder

Abstract

Overactive bladder (OAB), an under-diagnosed and under-treated condition, is a symptom complex characterized by urinary urgency, with or without urinary incontinence. Although antimuscarinic agents are the established first-line pharmacological treatment, insufficient efficacy, resistance and adverse effects such as dry mouth, constipation and dysuria have created the need for better drugs. Mirabegron, an oral beta-3-adrenergic agonist and first in a new class of drugs, has been recently approved by the US Food and Drug Administration to treat adults with OAB with symptoms of urge urinary incontinence, urgency and urinary frequency. By relaxing the detrusor muscle during the filling phase, mirabegron increases the storage capacity of the bladder and lengthens the interval between voiding. It does not affect bladder contraction or residual urine volume. In clinical trials, mirabegron significantly reduced the mean number of daily incontinence episodes as well as the mean number of micturitions per 24 h as compared with placebo. The most common side-effects are nasopharyngitis, urinary tract infections and headache. By exploiting a novel target, mirabegron represents a new therapeutic approach to OAB treatment with a distinct mechanism of action and gives a new hope to patients with significantly impaired quality of life due to OAB who are unable to tolerate antimuscarinic agents and who show insufficient effect from antimuscarinics.

Keywords

• Mirabegron
• overactive bladder
• urinary incontinence