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

Abstract 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 (50U, 100U or 150U). 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 100U ( p =0.086) and 150U ( p =0.261) BoNTA injections and >75% improvement in 40% of patients of both groups (100U [ p =0.058] and 150U [ p =0.022]). Complete continence was observed in 55% and 50% patients after 100U and 150U 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 >200ml in the 150U group and a few UTIs. Conclusions 100U and 150U BoNTA injections were well tolerated and have both shown to improve symptoms and QoL in patients with iOAB. Nevertheless, 100U injections showed a reasonable efficacy, with a lower risk of high PVR. Trial registration ClinicalTrials.gov NCT00231491.