Effects of oxcarbazepine and phenytoin on the EEG and cognition in healthy volunteers

We studied the EEG and cognitive effects of oxcarbazepine (OXC) and phenytoin (PHT) using a double-blind, randomized, parallel-group design. Thirty-two healthy volunteers received a maximum of 1200 mg of OXC or 360 mg of PHT. EEG and cognitive testing were performed at baseline and after 12 weeks of treatment. For each subject and measure, test–retest Z scores were calculated from regression equations derived from 73 healthy controls. Twenty-six subjects completed the study. Both the OXC and PHT groups had significant slowing of the EEG peak frequency and increased relative theta and delta power. Differences between AEDs (antiepileptic drugs) were not significant. Significant cognitive effects were seen on 5 of 20 measures, primarily measures of motor speed and reaction time. Again, there were no significant differences between AEDs. The only significant difference between AEDs was for the POMS–Vigor scale, favoring OXC. The small sample size may have contributed to the lack of significant differences between AEDs.