Mirabegron in Overactive Bladder and Its Role in Exit Strategy After Botulinum Toxin Treatment in Children

PURPOSE: Mirabegron is a recent addition to the management options of overactive bladder (OAB) in children. The purpose of this study was to ascertain the role of Mirabegron in the treatment algorithm of therapy-resistant OAB especially after botulinum toxin. METHODS: Case notes of all children receiving Mirabegron between July 2017 and February 2020 were reviewed. RESULTS: Forty one children (21 females, 20 males), mean age 12.6 [8-17] years old, commenced Mirabegron: 35 idiopathic OAB, 6 neuropathic OAB. The mean duration of treatment was 20.7 [3-45] months. In total 24 (59%) had Mirabegron after partial/no response to anticholinergics, and 17 (41%) patients had Mirabegron subsequent to botulinum toxin A (BtA) as an exit strategy. In total 35 (85%) patients had combination therapy (Mirabegron and anticholinergics), and 6 (15%) patients had Mirabegron only. Fourteen (34%) had complete response, 17 (41%) had partial response, and 10 (24%) had no response. Side effects were reported in 7 (17%) patients with discontinuation necessitated in 3. CONCLUSION: Mirabegron when used alone or in combination with anticholinergics resulted in complete/partial response in 76% of anticholinergic therapy-resistant OAB. In addition to being an important step in treatment escalation after no/partial response to anticholinergics, it has a crucial role in the exit strategy for recurring symptoms after BtA wears off.