Effect of naloxone infusion on the rate of epileptiform discharges in patients with complex partial seizures

In experimental studies, endogenous opioids have shown protective effects on seizure recurrence and facilitatory effects on postictal inhibition that were reversed by the opioid antagonist, naloxone. We evaluated the effect of all-night continuous infusion of 10 mg naloxone on the rate of focal interictal epileptiform discharges (FIEDs) during sleep in eight men with complex partial seizures (CPS) during 2 consecutive nights. Patients with abundant FIEDs during the control night showed a mean increase of 39% in the rate of FIEDs per unit of time during the naloxone infusion night. During the naloxone infusion night, mean nocturnal plasma prolactin (PRL) concentrations in this group of patients showed significant elevation, which was correlated with increased density of FIEDs. All-night infusion of naloxone failed to show any effect on the remaining three patients with minimal or no FIEDs during the control night. Mean nocturnal plasma PRL concentrations in this group of patients was significantly lower than in the former group. Our data support the notion that, in response to interictal or ictal discharges, endogenous opioid peptides may exert an inhibitory action that is reversible by administration of naloxone.