Mirabegron versus antimuscarinics for overactive bladder: which is more effective?

This study investigated the safety and efficacy of mirabegron (Myrbetriq) versus anti-muscarinics in patients with overactive bladder (OAB). The study concluded that mirabegron was as effective as anti-muscarinics in improving OAB symptoms, with fewer side effects.

Oral anti-muscarinic agents, such as solifenacin (Vesicare), are a typical first-choice therapy for OAB. This type of treatment relaxes the muscle of the bladder, reducing the urge to urinate and episodes of urine leakage (incontinence). However, side effects make their long-term use difficult for many patients.

Mirabegron is a new alternative to anti-muscarinic agents. The safety and effectiveness of mirabegron compared to classic OAB medications remains under investigation.

This study analyzed forty-four studies (including 27,309 patients) comparing 50 mg mirabegron therapy to different anti-muscarinics. These included darifenacin (Enablex), oxybutynin (Ditropan), and solifenacin, among others. The average follow-up period was 12 weeks.

Mirabegron was as effective as other treatments at reducing the number of daily urinations. Only solifenacin (10 mg) was significantly more effective than mirabegron at reducing urination frequency. Solifenacin had a 100% probability of being more effective than mirabegron.

Solifenacin was also the only treatment significantly more effective than mirabegron in improving daily episodes of incontinence. Solifenacin had a 97% probability of being more effective in reducing the number of urine leaks compared to mirabegron. Compared to other anti-muscarinics, mirabegron was as effective at reducing incontinence. 

Mirabegron was associated with a lower risk of side-effects compared to anti-muscarinics. Dry mouth and constipation are common complaints among patients receiving anti-muscarinics, and are often the cause of stopping treatment. The risk of these side effects with mirabegron treatment, however, was found to be similar to that of a placebo. Solifenacin (10 mg) and fesoterodine (8 mg), were associated with the highest number of adverse events.

This study concluded that mirabegron was as effective as most anti-muscarinics in improving OAB symptoms, with fewer side effects.

Astellas Pharma, Inc., the manufacturer of mirabegron, provided support for this study.