Evaluation of the Efficacy and Tolerance of Low Doses of Ethosuximide in the Treatment of Peripheral Neuropathic Pain

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).