Currently Enrolling Trials
Myrbetriq (mirabegron) selective beta-3 adrenoceptor (Beta3-AR) agonist. The drug activates Beta3-ARs on the detrusor muscle of the bladder to facilitate filling of the bladder and storage of urine.
Myrbetriq is specifically indicated for the following:
- overactive bladder (OAB) in adult patients with symptoms of urge urinary incontinence, urgency, and urinary frequency, either alone or in combination with the muscarinic antagonist solifenacin succinate
- Neurogenic detrusor overactivity (NDO) in pediatric patients aged 3 years and older and weighing 35 kg or more
Myrbetriq for adults is supplied as an extended release tablet designed for oral administration. The recommended initial dose of the drug is is 25 mg once daily, with or without food. This starting dose is effective within 8 weeks. Based on individual efficacy and tolerability, it may be increased to 50 mg once daily. It should be swallowed whole with water.
Myrbetriq for NDO in pediatric patients 3 years and older is supplied as a granule for oral suspension. The recommended dosing is as follows:
- Pediatric Patients weighing less than 35 kg: Use Myrbetriq Granules: The recommended starting dose of Myrbetriq Granules is weight-based and administered as an extended-release oral suspension once daily. After 4 to 8 weeks, increase to the lowest effective dose without exceeding the maximum recommended dose.
- Pediatric Patients weighing 35 kg or more: Use Myrbetriq or Myrbetriq Granules: The recommended starting dosage of Myrbetriq is 25 mg orally once daily. After 4 to 8 weeks, the Myrbetriq dose may be increased to 50 mg orally once daily. The recommended starting dosage of Myrbetriq Granules, administered as an extended-release oral suspension, is 6 mL (48 mg) orally once daily. After 4 to 8 weeks, increase to a maximum dosage of Myrbetriq Granules 10 mL (80 mg) orally once daily.
The FDA approval of Myrbetriq for adults was based on the results of three, 12-week, double-blind, randomized, placebo-controlled, parallel group, multicenter clinical trials in subjects with overactive bladder with symptoms of urge urinary incontinence, urgency, and urinary frequency. In Study 1, subjects were randomized to placebo, Myrbetriq 50 mg, Myrbetriq 100 mg, or an active control once daily. In Study 2, subjects were randomized to placebo, Myrbetriq 50 mg or Myrbetriq 100 mg once daily. In Study 3, subjects were randomized to placebo, Myrbetriq 25 mg or Myrbetriq 50 mg once daily. The co-primary efficacy endpoints in all three trials were change from baseline to end of treatment (Week 12) in mean number of incontinence episodes per 24 hours and change from baseline to end of treatment (Week 12) in mean number of micturitions per 24 hours, based on a 3-day micturition diary. An important secondary endpoint was the change from baseline to end of treatment (Week 12) in mean volume voided per micturition. Myrbetriq 25 mg was effective in treating the symptoms of OAB within 8 weeks, and Myrbetriq 50 mg was effective in treating the symptoms of OAB within 4 weeks. Efficacy of both 25 mg and 50 mg doses of Myrbetriq was maintained through the 12-week treatment period.
The FDA approval of Mybetriq and Myrbetriq Granules for the pediatric NDO indication was established in a 52-week, open-label, baseline-controlled, multicenter, dose titration study in pediatric patients 3 to 17 years of age (n=86). Mybetriq and Myrbetriq Granules were administered orally once daily. All patients initially received a weight-based starting dose equivalent to 25 mg daily dose followed by dose titration to a dose equivalent of 50 mg daily dose. The duration of the dose titration period was up to 8 weeks and this period was followed by a dose maintenance period that continued for the duration of the 52-week study. Improvements occurred in patients' maximum cystometric (bladder) capacity, number of detrusor (bladder wall muscle) contractions, volume of urine held until first detrusor (bladder wall muscle) contraction and number of daily urine leakage episodes after 24 weeks of treatment.
Adverse reactions associated with the use of Mybetriq in adults may include, but are not limited to, the following:
- urinary tract infection
Adverse reactions associated with the use of Mybetriq in pediatric patients may include, but are not limited to, the following:
Mechanism of Action
Myrbetriq (mirabegron) is an agonist of the human beta-3 adrenergic receptor (AR) as demonstrated by in vitro laboratory experiments using the cloned human beta-3 AR. Mirabegron relaxes the detrusor smooth muscle during the storage phase of the urinary bladder fill-void cycle by activation of beta-3 AR which increases bladder capacity.
For additional information regarding Myrbetriq or overactive bladder, please visit the Myrbetriq web page.