Efficacy and Safety of Low Doses of OnabotulinumtoxinA for the Treatment of Refractory Idiopathic Overactive Bladder: A Multicentre, Double-Blind, Randomised, Placebo-Controlled Dose-Ranging Study

Background: In the treatment of patients with idiopathic overactive bladder (iOAB), high doses of botulinum toxin type A (BoNTA) were often associated with complications resulting from high postvoid residuals (PVR), leading to clean intermittent catheterisation (CIC) and urinary tract infections (UTI). Objective: Evaluate the efficacy and tolerability of low doses of onabotulinumtoxinA compared to placebo in patients with iOAB. Design, setting, and participants: Between 2005 and 2009, adults with persistent iOAB were included in a prospective, randomised, double-blind, placebo-controlled comparative trial. Intervention: Patients were randomised to undergo a single intradetrusor injection procedure of either placebo or onabotulinumtoxinA (50 U, 100 U or 150 U). Measurements: The initial evaluations (ie, clinical and urodynamic variables as well as quality of life [QoL]) were repeated at day 8 and months 1, 3, 5, and 6. Results and limitations: Ninety-nine patients were included in the efficacy analysis. Three months after the procedure, we observed > 50% improvement versus baseline in urgency and urge urinary incontinence (UUI) in 65% and 56% of patients who respectively received 100 U (p = 0.086) and 150 U (p = 0.261) BoNTA injections and > 75% improvement in 40% of patients of both groups (100 U [p = 0.058] and 150 U [p = 0.022]). Complete continence was observed in 55% and 50% patients after 100 U and 150 U BoNTA treatment, respectively, at month 3. Frequency symptoms and QoL improved up to the 6-mo visit. We observed only three patients with a PVR > 200 ml in the 150 U group and a few UTIs. Conclusions: 100 U and 150 U BoNTA injections were well tolerated and have both shown to improve symptoms and QoL in patients with iOAB. Nevertheless, 100 U injections showed a reasonable efficacy, with a lower risk of high PVR. Trial registration: ClinicalTrials.gov NCT00231491. (C) 2011 European Association of Urology. Published by Elsevier B. V. All rights reserved.