Serum carnitine levels in epileptic children before and during treatment with valproic acid, carbamazepine, and phenobarbital.

Serum levels of free, acyl, and total carnitine were determined in 32 patients with seizures, before and after 3, 6, and 12 months of treatment with valproic acid (17 patients), carbamazepine (10 patients), or phenobarbital (5 patients). In all three treated groups, both free and total carnitine levels showed a significant decline with respect to pretreatment levels. This decline was most marked and most consistent in patients treated with valproic acid. In 35% of the patients in this group, carnitine deficiency (ie, total carnitine < 30 micromol/L) was observed by month 12. In none of the three groups were serum carnitine levels significantly correlated with the serum concentration of the drug. These findings suggest a need to monitor serum carnitine levels in children treated with any of these drugs.