To the Editor.
—The study by Dr Scolnik and colleagues1 has two important flaws. The authors acknowledge that "even when not exposed to medications, infants of mothers with epilepsy have higher rates of malformations than those in the general population." They then compare 36 patients taking carbamazepine, of whom only 30 (83%) were epileptic, with 34 patients taking phenytoin, of whom 33 (97%) were epileptic (χ2=3.7, P=.05). The epileptics receiving phenytoin are inherently more likely to bear malformed children.In addition, the mean maternal dose of phenytoin was 5.9 mg/kg per day and for carbamazepine 8.9 mg/kg per day. For a 60-kg woman, that translates to a daily dose of 354 mg of phenytoin and 534 mg of carbamazepine. The Physicians' Desk Reference2 lists the average adult maintenance doses for phenytoin as 300 to 400 mg per day and for carbamazepine as 800 to 1200 mg
Jeret JS, Centre R. Neurodevelopment After In Utero Exposure to Phenytoin and Carbamazepine. JAMA. 1994;272(11):850. doi:10.1001/jama.1994.03520110028017