The effect of valproic acid on plasma carnitine levels
G. Opala, S. Winter, C. Vance, H. Vance, H. T. Hutchison and L. S. Linn
Metabolic Research and Analysis Inc, Fresno, Calif 93726.
Plasma total, free, and acyl carnitine levels were determined in four
groups of children: (1) those treated with valproic acid as monotherapy (n
= 43), (2) those treated with valproic acid plus other antiepileptics as
polytherapy (n = 91), (3) those treated with other antiepileptic drugs
alone (n = 43), and (4) normal patients (n = 89). The mean free carnitine
level was significantly lower in both the valproic acid monotherapy (29.9
mumol/L) and polytherapy (21.4 mumol/L) groups compared with normal
subjects (36.8 mumol/L); it was also significantly lower than that in
patients treated with other antiepileptic drugs (36.7 mumol/L). Comparison
of valproic acid polytherapy and monotherapy yielded significantly lower
free carnitine levels in the polytherapy group. The ratios of acyl to free
carnitine for monotherapy (0.41) and polytherapy (0.45) were significantly
higher than that in the normal group (0.25). This study indicates that a
general decrease in the carnitine pool should be anticipated in patients
taking valproic acid polytherapy and, to a lesser degree, monotherapy.
Carnitine levels in the group taking other drugs did not differ from
normal.
