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Published on: September 2, 2020
Intravesical resiniferatoxin for the treatment of interstitial cystitis: a randomized, double-blind, placebo
Christopher K Payne1, Philip G Mosbaugh, John B Forrest
1Stanford University School of Medicine, Stanford, California, USA. cpayne@stanford.edu
Purpose:
Interstitial cystitis is a painful bladder condition of unknown etiology and poorly understood pathophysiology. Current therapies have met with limited success. Vanilloid receptor agonists such as resiniferatoxin (RTX) desensitize C-fibers that transmit pain; it is hypothesized that such drugs will be effective in the treatment of interstitial cystitis and painful bladder syndrome by decreasing the pain that leads to urinary frequency and urgency.
Materials And Methods:
A randomized, double-blind, placebo controlled study was conducted in 163 patients with interstitial cystitis. Participants were randomly assigned to receive a single intravesical dose of 50 ml of either RTX 0.01 microM, 0.05 microM, 0.10 microM, or placebo. Safety and efficacy was evaluated over 12 weeks. The primary efficacy endpoint was the Global Response Assessment, a 7-point scale rating overall change in symptoms of interstitial cystitis after 4 weeks. Secondary efficacy endpoints included reduction in pain, urgency, frequency, nocturia, average void volume, and the O'Leary-Sant Symptom and Problem Indexes.
Results:
RTX did not improve overall symptoms, pain, urgency, frequency, nocturia, or average void volume during 12 weeks followup. RTX resulted in a dose-dependent increase in the incidence of instillation pain, but was otherwise generally well tolerated.
Conclusions:
In the largest prospective, randomized clinical trial reported to date with intravesical vanilloid therapy, single administration of RTX at doses of 0.01 microM to 0.10 microM was not effective in patients with interstitial cystitis.
Insights
Resiniferatoxin (RTX) did not effectively treat interstitial cystitis symptoms in a large clinical trial. The vanilloid receptor agonist showed no improvement in pain or urinary issues and increased instillation pain.
Area of Science:
- Urology
- Pain Management
- Clinical Pharmacology
Background:
- Interstitial cystitis (IC) is a chronic, painful bladder condition with unknown causes and limited treatment options.
- Vanilloid receptor agonists, like resiniferatoxin (RTX), target pain-transmitting C-fibers and were hypothesized to alleviate IC symptoms.
Purpose of the Study:
- To evaluate the efficacy and safety of intravesical resiniferatoxin (RTX) for treating interstitial cystitis (IC) and painful bladder syndrome.
- To determine if RTX can reduce pain, urgency, frequency, and other symptoms associated with IC.
Main Methods:
- A randomized, double-blind, placebo-controlled study involving 163 IC patients.
- Patients received a single intravesical dose of RTX (0.01, 0.05, or 0.10 microM) or placebo.
- Efficacy assessed over 12 weeks using Global Response Assessment, symptom diaries, and O'Leary-Sant Indexes.
Main Results:
- RTX did not significantly improve overall IC symptoms, pain, urgency, frequency, or nocturia compared to placebo.
- A dose-dependent increase in instillation pain was observed with RTX administration.
- RTX was generally well tolerated apart from the instillation-related pain.
Conclusions:
- Single intravesical administration of RTX at tested doses (0.01-0.10 microM) was ineffective for treating interstitial cystitis.
- This study represents the largest prospective randomized trial of intravesical vanilloid therapy for IC to date.
- Further research into vanilloid receptor modulation for IC may require different approaches or agents.
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