Dextromethorphan Versus Placebo for Neuropathic Pain
Status:
Completed
Trial end date:
2001-02-01
Target enrollment:
Participant gender:
Summary
In our current clinical trial, we are comparing the effects of two NMDA receptor antagonists
to placebo in patients with painful distal symmetrical diabetic neuropathy or post-herpetic
neuralgia. The treatments in this three-period crossover study are dextromethorphan, up to
920 mg/day (about 8 times the antitussive dose), memantine, 30-50 mg/day, and placebo.
Memantine is an NMDA antagonist used in Europe to treat Parkinson's disease and Alzheimer's
disease. The underlying hypothesis, based on studies of painful neuropathies in animal
models, is that neuropathic pain is caused largely by sensitization of central nervous system
neurons caused by excitatory amino acid neurotransmitters, acting largely through NMDA
receptors. A previous small trial of dextromethorphan suggested efficacy in diabetic
neuropathy pain. The study requires one visit to the NIH outpatient Pain Research Clinic, and
consists of three 9-week treatment periods. Patients who respond to one of the medications
will be invited to participate in further controlled studies of the medication followed by up
to several years of open-label treatment under continued observation.
Phase:
Phase 2
Details
Lead Sponsor:
National Institute of Dental and Craniofacial Research (NIDCR)