Mirabegron is a β3
adrenoceptor agonist licensed for the treatment of
overactive bladder symptoms, such as urinary urgency or urgency incontinence. β3
adrenoceptor activation causes detrusor muscle relaxation, but
mirabegron may also act by binding other targets in the bladder, and it may also reduce activity in sensory nerves. Phase III clinical trials (
SCORPIO, ARIES, and CAPRICORN) evaluated
mirabegron at various doses, demonstrating reduction from baseline to endpoint in mean incontinence episodes and mean number of micturitions per 24 h (coprimary endpoints), along with health-related quality of life and a range of secondary measures. Efficacy was seen in many patients who had previously discontinued
antimuscarinic therapy on the grounds of lack of efficacy or poor tolerability. Treatment emergent adverse effects were documented in a long-term study (TAURUS), mostly being of mild or moderate severity. The most frequent adverse effects were
hypertension, dry mouth,
constipation, and
headache, with a lower incidence of dry mouth than for the
antimuscarinic active comparator. Efficacy and safety are not substantially different in older patients. A urodynamic safety study in men showed no consistent effect on voiding function, but a small increase in postvoid residual. Use of
mirabegron in combination with α-
adrenergic blockers does not appear to increase adverse effects.
Dose reduction is needed in people with severe
renal failure, or moderate
hepatic failure. Dose adjustment is not needed in relation to food intake. Ongoing research is evaluating the potential for combination
therapy with
antimuscarinics.