Intravesical botulinum toxin-A injections reduce bladder pain of interstitial cystitis/bladder pain syndrome refractory to conventional treatment – A prospective, multicenter, randomized, double-blind, placebo-controlled clinical trial

Purpose: Intravesical onabotulinumtoxinA (BoNT-A) injection is a beneficial treatment for interstitial cystitis/bladder pain syndrome (IC/BPS), yet its therapeutic efficacy remains to be validated. This study tests efficacy and safety of intravesical BoNT-A injections for treatment of IC/BPS. Materials and Methods: A multicenter, randomized, double-blind, placebo-controlled trial in patients with IC/BPS refractory to conventional treatment. Patients were randomized in a 2:1 ratio to hydrodistention plus suburothelial injections of BoNT-A 100 U (Botox group) or the equivalent amount of normal saline (N/S group). The primary endpoint was a decrease in pain assessed using a visual analog scale (VAS) at week 8 after treatment. Secondary endpoints included voiding diary and urodynamic variables. The Wilcoxon sign rank and rank sum tests were used for statistical analyses. Results: A total of 60 patients (8 males, 52 females, age 50.8 ± 13.9 years) including 40 in the Botox and 20 in the N/S groups were enrolled. At week 8, a significantly greater reduction of pain was observed in the Botox group compared to the N/S group (−2.6 ± 2.8 vs. −0.9 ± 2.2, P = 0.021). The other variables did not differ significantly between groups except for cystometric bladder capacity, which was increased significantly in the Botox group. The overall success rates were 63% (26/40) in the Botox group and 15% (3/20) in the N/S group (P = 0.028). Adverse events did not differ between the groups. Conclusion: Intravesical injections of 100 U of BoNT-A effectively reduced bladder pain symptoms in patients with IC/BPS. The adverse events were acceptable. Neurourol. Urodynam. 35:609–614, 2016.