Beta-3 agonist shows benefit for OAB in older adults

Mirabegron (Myrbetriq) is effective and well tolerated in patients age 65 or older with overactive bladder, results of a randomized, placebo-controlled study show.

Mirabegron (Myrbetriq) is effective and well tolerated in patients age 65 or older with overactive bladder (OAB), results of a randomized, placebo-controlled study show.

The beta-3 agonist reduced micturition frequency and incontinence episodes versus placebo in the study, which is the first prospectively designed investigation of the medication specifically in older adults, according to investigator Adrian Wagg, MB BS, of the University of Alberta in Edmonton, Canada.

Treatment was well tolerated and not associated with adverse cognitive effects, Dr. Wagg said at the International Continence Society annual meeting in Philadelphia.

Mirabegron offers an alternative to antimuscarinic agents, which are associated with adverse effects that can limit adherence to treatment, according to Dr. Wagg and co-investigators.

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“Overactive bladder is a problem mainly experienced by older people, and we have an alternative for treatment, so we felt it was about time that we trialed this in older people,” Dr. Wagg said in a podium presentation.

The 12-week phase IV, double-blind, randomized PILLAR study included patients at least 65 years of age who had OAB symptoms for at least 6 months. A total of 887 patients, of whom 249 (28.1%) were at least 75 years of age, were randomized to receive mirabegron (n=445) or placebo (n=442).

Patients randomized to receive mirabegron had the option of dose escalation to 50 mg/day, depending on tolerability, Dr. Wagg said.

There was a statistically significant difference in favor of mirabegron for the co-primary endpoints of the study, which were incontinence episodes and number of micturitions per 24 hours from baseline to end of treatment, Dr. Wagg reported.

The mean change in number of incontinence episodes in 24 hours was –1.57 for the placebo arm and –2.06 for the mirabegron arm (p<.001), according to his report. Similarly, the mean change in number of micturitions over 24 hours was reported to be –2.0 for placebo and –2.5 for mirabegron (p<.001).

Patients receiving mirabegron also had a larger change in mean volume voided per micturition from baseline to end of treatment, at 32.44 mL versus 18.49 mL (p<.001), as well as a significantly greater improvement in symptoms as measured by the Overactive Bladder Questionnaire, Dr. Wagg said.

Next: Very few serious drug-related treatment-emergent adverse eventsThere were very few serious drug-related treatment-emergent adverse events in the study, according to Dr. Wagg, at 2.7% for placebo and 3.4% for mirabegron. The overall rate of treatment-emergent adverse events was 47% for mirabegron versus 39% for placebo, with the most frequently reported including urinary tract infection, headache, fatigue, diarrhea, and upper respiratory tract infection, among others.

Cognitive impairment was assessed using the Montreal Cognitive Assessment Score (MoCA), which Dr. Wagg said is sensitive to mild cognitive impairment and executive dysfunction. There was no change in MoCA score versus placebo over the time course of the study, he reported.

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Escalating the dose to 50 mg/day was not associated with additional benefit, except for an improvement in micturition frequency, Dr. Wagg and co-investigators said in the study’s abstract.

Further analyses of the PILLAR study looking at concomitant medications and chronic medical conditions in these older adults will be reported at a later date, according to Dr. Wagg.

“These people were polypharmaceutical and multiply comorbid,” he said.


The PILLAR study was sponsored by Astellas Pharma Global Development, Inc.