Naloxone-induced electrographic seizures in the primate.

Electrographic seizure activity was recorded shortly following naxolone injections in artificially ventilated, methadone-treated stump-tailed macaques. Plasma-methadone concentrations prior to seizure activity were many times higher than those that have produced respiratory depression and death in nonventilated monkeys. The duration of seizure activity was clearly related to the dose of naloxone. Naloxone was without epileptogenic properties in animals that had not been pretreated with methadone. The results suggest that methadone and naloxone have additive epileptogenic properties when high blood levels of methadone are achieved in the artificially ventilated primate. Naloxone was devoid of antagonistic properties with respect to opiate-induced electroencephalographic spiking activity.