An Open Label, Dose Finding Trial of Viagra for the Treatment of Neuropathic Pain (in Diabetes Mellitus)

The purpose of this study is to study if sildenafil (Viagra) is effective in improving neuropathic pain. This will be an open label study at 3 doses of sildenafil (25 mg, 50 mg and 100 mg). If this study suggests efficacy, the information will be used to plan a placebo controlled, double-blind study in the future.

Study Overview

• Status: Completed
• Conditions: Diabetic Neuropathy
• Intervention / Treatment: Drug: sildenafil (Viagra)

Detailed Description

Neuropathic pain is a common problem resulting from a diverse group of disorders including nerve injuries and neuropathies related to diabetes and other disorders. Pharmacologic agents are available such as gabapentin, which can successfully treat many patients. For many however there is inadequate treatment available, due to lack of efficacy and poor tolerability and the need for new pharmacologic agents is recognized.

We propose to study if sildenafil is effective in improving neuropathic pain, in patients with diabetes mellitus. Our primary outcome will be a reduction in the weekly average 11 point Likert pain scale (0 - no pain, 10 - worst possible pain) at 8 weeks. Secondary outcomes will include the Rand-36 quality of life scale, McGill visual analogue scale (VAS) and a sleep interference scale.

This will be an open label study at 3 doses of sildenafil (25 mg, 50 mg and 100 mg). Patients will begin at 25 mg at night for 1 week. If pain continues, the dose will be increased to 50 mg at night for 1 week. If pain continues the dose will be increased to 100 mg at night. Subjects will be on the medication for 8 weeks. If this study suggests efficacy, the information will be used to plan a placebo controlled, double-blind study in the future.

We propose to study if sildenafil is effective in improving neuropathic pain. Our primary outcome will be a reduction in the weekly average 11 point Likert pain scale (0 - no pain, 10 - worst possible pain) at 8 weeks. Secondary outcomes will include the Rand-36 quality of life scale, McGill visual analogue scale (VAS) and a sleep interference scale.

This will be an open label study at 3 doses of sildenafil (25 mg, 50 mg and 100 mg). Patients will begin at 25 mg at night for 1 week. If pain continues, the dose will be increased to 50 mg at night for 1 week. If pain continues the dose will be increased to 100 mg at night. Subjects will be on the medication for 8 weeks. If this study suggests efficacy, the information will be used to plan a placebo controlled, double-blind study in the future.

• Study Type: Interventional
• Enrollment (Actual): 8
• Phase: Phase 4

Contacts and Locations

Study Locations

• United States
  • New York
    • New York, New York, United States, 10022
      • Peripheral Neuropathy Center - Weill Cornell Medical College

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• Patients with signs and symptoms of a diabetic peripheral neuropathy as diagnosed by a neurologist with neuropathic pain will be included. The pain will have been present for at least 6 months. Patients may be on other medications for neuropathic pain such as anti-epileptic medications or tricyclic anti-depressants, however must be on a stable dose for 4 weeks prior to and during the study. Eligible patients must have a score of at least 40 on the VAS.

Exclusion Criteria:

• Previous adverse reaction to viagra
• Blood pressure < 90/50 or > 170/100
• unstable angina
• retinitis pigmentosa,
• myocardial infarction stroke or life-threatening arrhythmia within the last 6 months
• hemoglobulin A1c > 11
• HIV infection
• history of priapism
• hepatic or renal failure
• pregnancy
• current or past use of nitrates

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Non-Randomized
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Our primary outcome will be a reduction in the weekly average 11 point Likert pain scale (0 - no pain, 10 - worst possible pain) at 8 weeks.

Secondary Outcome Measures

Outcome Measure
Secondary outcomes will include the Rand-36 quality of life scale, McGill visual analogue scale (VAS) and a sleep interference scale.

Collaborators and Investigators

• Sponsor: Weill Medical College of Cornell University
• Collaborators: Pfizer
• Investigators: Principal Investigator: Thomas H Brannagan, MD, Weill Medical College of Cornell University

Study record dates

Study Major Dates

• Study Start: August 1, 2004
• Primary Completion (Actual): July 1, 2006
• Study Completion (Actual): July 1, 2006

Study Registration Dates

• First Submitted: September 12, 2005
• First Submitted That Met QC Criteria: September 12, 2005
• First Posted (Estimate): September 19, 2005

Study Record Updates

• Last Update Posted (Estimate): March 25, 2008
• Last Update Submitted That Met QC Criteria: March 24, 2008
• Last Verified: March 1, 2008

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Glucose Metabolism Disorders; Metabolic Diseases; Nervous System Diseases; Pain; Neurologic Manifestations; Endocrine System Diseases; Diabetes Complications; Neuromuscular Diseases; Peripheral Nervous System Diseases; Diabetes Mellitus; Neuralgia; Diabetic Neuropathies; Molecular Mechanisms of Pharmacological Action; Vasodilator Agents; Urological Agents; Enzyme Inhibitors; Phosphodiesterase Inhibitors; Phosphodiesterase 5 Inhibitors; Sildenafil Citrate
• Other Study ID Numbers: 1103-032