Similar Efficacy, but Fewer AEs, With Vibegron Versus Antimuscarinics for OAB

By Marilynn Larkin

March 09, 2021

NEW YORK (Reuters Health) - In a review of randomized, controlled trials, vibegron showed similar efficacy to antimuscarinics for overactive bladder (OAB), but fewer treatment-emergent adverse events (AEs).

Dr. Yuan Gao of Weifang People's Hospital in Shandong Province, China, and colleagues did the meta-analysis, published in Medicine, which included three randomized, controlled trials involving 1,751 patients. Participants received 100 mg vibegron once daily or tolterodine (different doses) or imidafenacin (0.1 mg twice daily) for 12 weeks.

Efficacy end points were the mean number of episodes, per day, of micturitions, urgency, urgency incontinence, and incontinence.

Analysis of the three studies indicated no significant differences between vibegron and antimuscarinics in terms of efficacy, although patients treated with vibegron had significantly increased urination volume.

Vibegron was better tolerated, with fewer reports of dry mouth and drug-related treatment-emergent AEs. However, the tolterodine dose was different in the two trials that looked at these end points.

No between-group differences were seen for serious AEs or discontinuations due to AEs.

Dr. Gao did not respond to requests for a comment, but two experts commented by email to Reuters Health.

Dr. Christopher Hartman, Chief of Urology at LIJ Forest Hills in Queens, New York, said the findings align with his clinical experience. "B3 agonists, including both mirabegron and the newer vibegron, have been proven in numerous studies to offer similar or improved outcomes for patients with symptoms of OAB. More importantly, they have been proven to decrease the number of bothersome side effects that plague patients treated with anticholinergic/antimuscarinic medications."

That said, he noted, the review was based on only three randomized, controlled trials with different dosing regimens for the studied medications. "Furthermore, of the many anticholinergic medications used to treat symptoms of OAB, only two were studied among the three trials. Thus, it is impossible to draw conclusions from this study regarding the safety and efficacy profile of other commonly used anticholinergic medications as compared to vibegron."

In the US, cost and accessibility will be issues for for vibegron, which recently gained FDA approval and will become available in the US in April 2021, he said.

"Mirabegron, the more commonly used B3 agonist to treat symptoms of overactive bladder, does not have insurance coverage under many plans," he said. "Even under insurance plans that do cover the medication, patients often must try and fail treatment with one or more anticholinergic medications first."

Further, he noted, "For patients with uncontrolled preexisting hypertension or those in whom serious side effects occurred with B3 agonist medications, an antimuscarinic medication would be a more appropriate treatment option."

Dr. Mark Ellerkmann, Director of The Urogynecology Center at Mercy Medical Center in Baltimore said the findings "are consistent with prior studies comparing mirabegron with antimuscarinic medications used to treat patients with OAB."

"The authors note weaknesses of their study," he said, "including the obvious fact that their meta-analysis had very few studies, that long-term follow up was lacking and the dosing of tolterodine was different in the two RCTs studied."

Like Dr. Hartman, he noted that "often the choice will come down to cost and tier status coverage by a patient's individual medical plan." He added, "Patients opting to trial pharmacologic treatment of OAB symptoms with antimuscarinic/anticholinergics should be counseled regarding the associated risk of cognitive impairment, dementia and Alzheimer disease, and to this end, the lowest effective dose should be prescribed and consideration given to alternative medications such as beta-3 agonists."

SOURCE: Medicine, online February 5, 2021.