Oxcarbazepine-d4 is intended for use as an internal standard for the quantification of oxcarbazepine by GC- or LC-MS. Oxcarbazepine is a prodrug form of the antiepileptic compound 10,11-dihydro-10-hydroxy carbamazepine . It inhibits high-frequency repetitive firing of rat spinal cord neurons when used at a concentration of 1 μM. Oxcarbazepine protects against electroshock-induced tonic hindlimb extension (ED50s = 10-20 mg/kg), as well as seizures induced by pentylenetetrazole (PTZ; ) or picrotoxin in rodents (ED50s = 23-30 and 150-250 mg/kg, respectively). Formulations containing oxcarbazepine have been used in the treatment of epileptic seizures.