The FDA ( Food and Drug Administration ) has approved Myrbetriq ( Mirabegron ) extended-release tablets for the treatment of overactive bladder ( OAB ) with symptoms of urge urinary incontinence, urgency and urinary frequency.

Myrbetriq is a once daily oral beta-3 adrenergic agonist; it has been studied extensively in more than 10,000 individuals over 10 years. Myrbetriq offers a new treatment option for patients with overactive bladder.
Antimuscarinics are the current overactive bladder treatment standard.
Myrbetriq uses a distinct mechanism of action. Antimuscarinics work by binding to muscarinic receptors in the bladder and inhibiting involuntary bladder contractions; Myrbetriq relaxes 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.

The recommended starting dose for Myrbetriq is 25 mg once daily with or without food. Myrbetriq 25 mg is effective within eight weeks; based on individual efficacy and tolerability, the dose may be increased to 50 mg once daily.

Myrbetriq was studied in patients who were primarily Caucasian ( 94% ) and female ( 72% ) with a mean age of 59 years ( range 18-95 years ). The population included both naïve patients who had not received prior antimuscarinic pharmacotherapy for overactive bladder ( 48% ) and those who had received prior antimuscarinic pharmacotherapy for overactive bladder ( 52% ).

The approval of Myrbetriq was based on safety and efficacy data from three placebo-controlled Phase 3 studies, in which treatment with Myrbetriq 25 mg and 50 mg resulted in statistically significant improvement in efficacy parameters of incontinence episodes and number of urinations per 24 hours.

In treatment with Myrbetriq 25 mg, incontinence episodes were reduced by 1.36 episodes from a baseline of 2.65, a statistically significant reduction of 0.40 vs placebo in 12 weeks. The number of urinations was reduced by 1.65 urinations from a baseline of 11.68, a statistically significant reduction of 0.47 vs placebo in 12 weeks.

In treatment with Myrbetriq 50 mg, incontinence episodes were reduced by 1.49 episodes from a baseline of 2.71, a statistically significant reduction of 0.40 vs placebo in 12 weeks. Number of urinations was reduced by 1.75 urinations from a baseline of 11.70, a statistically significant reduction of 0.55 vs placebo in 12 weeks.

Myrbetriq was evaluated for safety in more than 2,700 patients in three, 12-week Phase 3 double blind, placebo-controlled studies and in a one year, randomized fixed dose, active-controlled study in patients with overactive bladder. The most commonly reported adverse reactions ( greater than 2% of Myrbetriq patients and greater than placebo ) were hypertension, nasopharyngitis, urinary tract infection and headache.

Myrbetriq will be supplied in 25 mg and 50 mg tablets.

Source: Astellas, 2012

XagenaMedicine2012