Mirabegron (β3-adrenoreceptor agonist) is a new molecule with a distinct mechanism of action from antimuscarinics. Combination therapy with solifenacin was recently studied in adult population. Our objective was to evaluate the efficacy and safety of mirabegron as add-on therapy, to treat urinary incontinence in children with idiopathic OAB, refractory/intolerant to antimuscarinics.
A prospective off-label study using add-on regimens of mirabegron was conducted with pediatric patients presenting no symptom improvement under intensive behavioural and medical therapies and/or significant side effects (S/E) on antimuscarinic dose escalation. Our primary outcome was better-reported efficacy than with the use of prior antimuscarinic monotherapy; secondary end-points were tolerability, safety and satisfaction. Efficacy and tolerability were assessed with: voiding diaries, post-void residuals (PVR), urine cultures, ECG and vital signs. Families were questioned for continence, S/E, compliance. The Wilcoxon signed rank test was used for statistical analysis.
Thirty-five patients were recruited at median age of 10.3 years and were on the add-on mirabegron for a median of 16.4 months. Median bladder capacity improved from 50% to 74% expected bladder capacity (p<0.001). Continence improved in all patients, with 12 being completely dry. Post-void residual was increased for 2 patients and one UTI was reported. Seven patients reported mild or moderate S/E, with two withdrawals because of S/E(1)/PVR(1).
Add-on mirabegron appeared as a safe alternative for children with refractory OAB. The dual therapy was well tolerated and adjusted-dose regimen appeared safe in this first pediatric study.
The Journal of urology. 2016 Jan 30 [Epub ahead of print]
Fannie Morin, Anne-Sophie Blais, Geneviève Nadeau, Katherine Moore, Lucie Genois, Stéphane Bolduc
Division of Urology, CHU de Québec-Université Laval, Québec, Québec, Canada., Division of Urology, CHU de Québec-Université Laval, Québec, Québec, Canada. Electronic address: .