Multiple Intravesical Instillations of Low-Dose Resiniferatoxin in the Treatment of Refractory Interstitial Cystitis

Abstract

Background: Current medications used in the treatment of interstitial cystitis (IC) have limited efficacy. This prospective study investigated the efficacy of multiple intravesical instillations of resiniferatoxin (RTX) at the concentration of 10 nM. Methods: Patients with proven IC previously treated with traditional medications for more than 6 months without clinical benefit were enrolled. They were excluded if bladder outlet obstruction or urinary tract infection was present. Intravesical instillation of low-dose RTX (10 nM) once weekly for 4 weeks was performed at the outpatient department. International Prostate Symptom Score (IPSS), 5-Point Pain Scale, and Quality of Life Index (QOL Index) were recorded. A videourodynamic study was done at baseline and 3 months after treatment. Results: The therapeutic results and urodynamic parameters were compared between baseline and 3 months. Thirteen patients, including 10 women and 3 men, were enrolled in this study. The mean duration of IC symptoms was 4.4 ± 2.5 years. The mean duration of active treatment was 15.3 ± 8.6 months. One female patient dropped out due to severe bladder pain after RTX instillation. Among the 12 patients who completed the study treatment, subjective assessment revealed that 2 had an excellent therapeutic result, 5 had an improved result and 5 remained unchanged from baseline. The overall satisfactory rate was 58.3%. IPSS, 5-Point Pain Scale, and QOL Index were significantly decreased after RTX treatment. There was no significant increase in mean functional bladder capacity or change in urodynamic parameters. No serious adverse event occurred after RTX treatment. Conclusions: This study suggests that multiple intravesical instillations of RTX at the concentration of 10 nM are effective in relieving lower urinary tract symptoms in patients with refractory IC. The treatment is tolerable and suitable for use on an outpatient clinic basis.