Anticonvulsant drugs and malformations is there a drug specificity?

The distribution of anticonvulsant drug therapy was studied in 318 malformed infants with known histories of maternal epilepsy. Data on the infants was collected from six birth defect monitoring programs in Europe and South America. Use of specific types of anticonvulsants varies widely among reporting countries. Heterogeneity of drug-malformation distribution, was analyzed to determine whether use of specific drugs were linked to specific malformations. A significant association was seen between maternal use of valproic acid and spina bifida, and a weaker, non-significant one between carbamazepine and spina bifida. Facial clefts were associated with both diphenylhydantoin and phenobarbitone use and also with polytherapy. These differences indicate that the actual drug used is significant for the teratogenic process. The technique may be useful in analysis of other drug-related teratogenic questions.