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

BackgroundIn 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).ObjectiveEvaluate the efficacy and tolerability of low doses of onabotulinumtoxinA compared to placebo in patients with iOAB.Design, setting, and participantsBetween 2005 and 2009, adults with persistent iOAB were included in a prospective, randomised, double-blind, placebo-controlled comparative trial.InterventionPatients were randomised to undergo a single intradetrusor injection procedure of either placebo or onabotulinumtoxinA (50 U, 100 U or 150 U).MeasurementsThe 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 limitationsNinety-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.Conclusions100 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 registrationClinicalTrials.gov NCT00231491.