Plasma concentrations of sodium valproate: their clinical value.

Plasma valproate concentrations were monitored prospectively in 54 previously untreated adult patients with epilepsy. Dose and plasma concentration were highly correlated. Adverse effects were common in association with plasma levels above 100 micrograms/ml. In patients suffering tonic-clonic seizures without focal symptoms, no seizures occurred when plasma levels were higher than 50 micrograms/ml. In patients with partial seizures, it was difficult to define a lower limit to a therapeutic range.