Mirabegron, a β3-adrenoceptor agonist, shows promise for treating urinary incontinence in children with overactive bladder (OAB) who are intolerant to or nonresponsive to antimuscarinics, say researchers.
Mirabegron is approved for the treatment of idiopathic OAB in adults but its use has not previously been evaluated in children.
In their off-label study, Blais et al. gave mirabegron to 58 children with OAB who had shown suboptimal responses to intensive behavioural therapy and medical therapy (with at least two antimuscarinics), or had suffered intolerable adverse effects. Median age at mirabegron initiation was 10.1 years and the drug was given for a median of 11.5 months.
Patients or their parents rated the efficacy of symptom relief using a standardized questionnaire: continence improved (defined as a reduction of ≥50% of incontinence episodes) in 52 of 58 patients, with complete dryness reported in 13 patients. Blais et al. found that median voided volumes on 3-day voiding diaries also improved following treatment, and that changes in voiding diaries correlated directly with continence changes reported by patients or their parents. The median number of incontinence episodes per day also decreased after treatment.
The researchers questioned families using the Patient Perception of Bladder Condition (PPBC) scale at study initiation and every 3 months. Median PPBC score improved from 4 (defined as a perception of [some] moderate symptoms associated with the patient's bladder condition) at study initiation, to 2 (defined as a perception of some very minor problems) at the end of the study.
Electrocardiogram, blood pressure, heart rate and blood test findings remained normal. Mild or moderate adverse effects (nausea, constipation, abdominal cramps, nasopharyngitis, blurred vision and behavioural changes) were reported in eight patients, with three patients discontinuing treatment owing to these effects.
“Mirabegron, a novel first-in-class therapy, appears to be a safe alternative for children with idiopathic OAB and allowed improvement of symptoms in patients refractory to antimuscarinics,” say the authors.
Blais, A. S. et al. Prospective pilot study of mirabegron in pediatric patients with overactive bladder. Eur. Urol. http://dx.doi.org/10.1016/j.eururo.2016.02.007 (2016)