Mirabegron in Overactive Bladder Management

Critical Medication Interaction Considerations

The American College of Cardiology and other guideline societies recommend avoiding compounding anticholinergic burden in patients with overactive bladder, as it increases the risk of cognitive impairment, urinary retention, and constipation, particularly in those taking trifluoperazine and trihexyphenidyl, making mirabegron a preferred choice over fesoterodine 1, 2
Adding fesoterodine to a patient's existing anticholinergic regimen, such as trihexyphenidyl, would increase the risk of severe constipation, urinary retention, and blurred vision, with a dry mouth NNH of 78 2, 3, 4

The American Urological Association recommends mirabegron as a treatment option for overactive bladder, with a number needed to treat (NNT) for continence of 12 and for UI improvement of 9, based on evidence from clinical trials 4, 5
Fesoterodine shows superior efficacy to tolterodine, but its advantage is negated by the unacceptable risk profile in patients with existing anticholinergic burden, according to the European Association of Urology 4, 5

The National Institute for Health and Care Excellence recommends considering the safety profile of mirabegron, which has minimal cardiovascular effects at therapeutic doses and no anticholinergic cognitive effects, making it a safer choice for patients on antipsychotics and antihypertensives 1, 2
Fesoterodine is associated with common antimuscarinic effects, including constipation, blurred vision, and urinary retention, with a higher risk of cognitive impairment in patients with existing anticholinergic load, according to the American Geriatrics Society 2, 3, 4