Therapeutic effect of multiple resiniferatoxin intravesical instillations in patients with refractory detrusor overactivity: A randomized, double-blind, placebo controlled study

Purpose: Previous study has shown that multiple intravesical instillations of resiniferatoxin (Sigma (R)) at 10 nM has therapeutic effects in patients with detrusor overactivity. To our knowledge the placebo effect of multiple instillations of low dose resiniferatoxin for neurogenic and nonneurogenic detrusor overactivity has not been investigated. In this randomized, double-blind, placebo controlled study we evaluated the therapeutic effects of this resiniferatoxin treatment. Materials and Methods: A total of 54 patients with detrusor overactivity refractory to anticholinergics were enrolled and randomly treated with 4 weekly intravesical instillations of 10 nM resiniferatoxin (26) or vehicle, consisting of 10% ethanol in normal saline, as the control group (28). The clinical effects of treatment on incontinence grade, incontinence episodes, general satisfaction, lower urinary tract symptoms and urodynamic parameters were assessed. Results: Three months after completing the 4 intravesical treatments the resiniferatoxin treatment group had a significantly higher percent of patients with excellent and improved results compared to the control group (19.2% vs 7.1% and 42.3% vs 14.2%, respectively, each p < 0.001). Treatment remained effective at 6 months in 13 patients (50%) in the resiniferatoxin group but in only 3 (11%) in the control group (p < 0.001). Bladder capacity was significantly increased and symptom scores significantly improved 3 months after treatment in the resiniferatoxin group but not in the control group. Conclusions: Multiple intravesical instillations of 10 nM resiniferatoxin were effective for improving the incontinence grade in 62% of patients at 3 months, of whom 50% maintained a therapeutic effect 6 months after treatment. The therapeutic effect of resiniferatoxin was significantly superior to that of placebo.