Chemotherapy Induced Painful Peripheral Neuropathy Ethosuximide (The CIN-E Study)

Inclusion Criteria: * Age \>/= 18 * Diagnosis of cancer * Willing and able to give informed consent to the CIN-E study and complete study questionnaires, this involves adequate understanding of written and spoken English (translators will not be used) * Chemotherapy-induced painful peripheral neuropathy as diagnosed by score of \>12 on the Leeds Assessment of Neuropathic Symptoms and Signs (S-LANSS) with a pain intensity rating of \>4, on a 11 point numeric rating scale (0= no pain, 10= worst possible pain). * Duration of chemotherapy-induced painful peripheral neuropathy \>4 weeks. Participant may either have completed chemotherapy, or be receiving ongoing chemotherapy. * Able to attend research centre according to the required visit schedule. * Diet allows bovine gelatine (present in both ethosuximide and placebo capsules) * Women of child-bearing potential must be using a reliable form of contraception i.e. oral contraceptives, a barrier method (condom or diaphragm), intra-uterine device or abstinence. Exclusion Criteria: * Renal impairment (serum creatinine \>1.5x normal level) * Deranged liver function (AST\>3x normal level) * Patients currently taking any anti-depressant medication, for example fluoxetine, paroxetine, citalopram, venlafaxine, amitriptyline, or within the past week. * Patients currently taking any other anti-epileptic drug, including gabapentin, or within the past week. * Pregnancy * Allergy to succinimides, ethosuximide, methsuximide, phensuximide. Pre-exisitng painful peripheral neuropathy of any other cause.