Evaluation of the efficacy and tolerance of low doses of ethosuximide in the treatment of peripheral neuropathic pain

Multicenter, randomized, double-blind, placebo-controlled therapeutic trial evaluating the efficacy and safety of low doses of ethosuximide in neuropathic pain patients.

Inclusion Criteria:

• Male or female (under effective contraception: pill, implant, IUD, sterilization) aged 18 years or older, suffering from peripheral neuropathic pain (DN4 ≥ 4) for more than 3 months, of intensity ≥ 4 on a numerical scale from 0 to 10, and whose analgesic treatment has been stable for more than a month,
• Patients affiliated to the French Social Security system,
• Patients whose free and informed consent has been obtained.

Exclusion Criteria:

• Pregnancy (βHCG+ blood) or breastfeeding,
• Neuropathic pain due to spinal cord or brain injury, phantom limb pain or algohallucinosis,
• Fibromyalgia or algodystrophy,
• Chronic pain syndrome that the patient cannot distinguish and/or is more intense than peripheral neuropathic pain,
• Significant abnormalities in liver (transaminases > 3N, cholestasis) and renal (MDRD < 60 mL/min) tests,
• Ongoing comorbidities: cancer, neurodegenerative pathology
• Severe depressive disorder in progress (as determined by the clinician), history of suicide attempts or hospitalization for depression,
• Diabetic patients (contraindicated due to the high sugar concentration of ethosuximide, 3g / 5 ml),
• Patients who have previously received ethosuximide (epilepsy or clinical trial),
• Surgery planned throughout the entire trial,
• Medical and surgical history incompatible with the study,
• Dependence on alcohol and/or drugs (for compliance purposes),
• Known allergy to succinimides (ethosuximide, methsuximide, phensuximide),
• Psychotic disorders,
• Epileptic patients,
• Patients benefiting from a legal protection measure (curatorship, guardianship, deprived of liberty or subject to judicial safeguard).

Double-blind Placebo and ethosuximide will be indistinguishable.