Vigabatrin, lamotrigine, topiramate and serum carnitine levels

Clinical studies indicate a decrease in free and total carnitine in children treated with old-generation antiepileptic drugs (especially valproate). Here, we studied the effect of new-generation antiepileptic drugs on serum carnitine levels. Serum carnitine levels were measured in 91 children: 24 treated with vigabatrin, 28 treated with lamotrigine, and 21 treated with topiramate. These drugs were given as monotherapy (54 children) or polytherapy (19 children). Eighteen additional children treated with valproate served as control subjects. Reduced mean serum carnitine level was evident only in children treated with valproate, with mean free and total carnitine level of 26.9 +/- 8.6 micromol/L and 29.1 +/- 10.4 micromol/L, respectively. In contrast, the mean serum carnitine levels of children treated with vigabatrin, lamotrigine, or topiramate were similar and normal. In these children, the free carnitine levels were 38.5 +/- 7.8 micromol/L, 37.2 +/- 7.7 microg/mL, and 40.4 +/- 8.7 micromol/L, respectively, and total carnitine levels were 43.5 +/- 8.8 micromol/L, 44.4 +/- 9.2 micromol/L, and 45.5 +/- 9.8 micromol/L (+/-S.D.), respectively. Only 4 children (treated with valproate) exhibited considerably lower serum carnitine levels. None of these children had significant clinical adverse effects attributable to carnitine deficiency. In conclusion, these new-generation antiepileptic drugs probably do not cause carnitine deficiency. In contrast, valproate may induce carnitine deficiency, but most cases are asymptomatic.