Valproate acute administration, EEG epileptic abnormalities, and ammonemia.

Acute, oral administration of 14.3 to 37.5 mg/kg magnesium valproate (peak serum concentrations, 65 to 139 micrograms/ml) increases spike-wave frequency at 2, 3, 4, and 5 hours postdrug, in the absence of hyperammonemia or significant correlations with ammonemia fluctuations. This observation suggests a direct role of valproate on neural activity.