Urodynamic effects of intravesical resiniferatoxin in humans: Preliminary results in stable and unstable detrusor

Purpose: Resiniferatoxin, a substance isolated from some species of euphorbia, a cactus-like plant, presents pharmacological effects similar to those of capsaicin. We studied the urodynamic effects of intravesical resiniferatoxin* in normal subjects and patients with unstable detrusor contraction to provide insight into the action mechanism of the molecule on sensory neurons and possible future pharmacological and clinical use. Materials and Methods: A total of 15 subjects with normal (8 patients) or unstable detrusor muscle (1 with detrusor instability and 6 with detrusor hyperreflexia) underwent urodynamic assessment during and after intravesical instillation of resiniferatoxin. Volume required to elicit the first desire to void, maximum bladder capacity and maximum bladder pressure were recorded during instillation of resiniferatoxin at a flow rate of 20 ml. per minute (normal subjects) or 15 minutes after instillation of 30 cc of a saline solution containing 10^-8 M. of resiniferatoxin and kept for 30 minutes in patients with unstable detrusor. The experiment was examined by the analysis of variance for repeated measures and post hoc comparisons were performed by Tukey-Kramer procedure. A p value