Investigators at the Karolinska Institute, Stockholm, Sweden; and centers in Oslo, Norway, and Milan, Italy, reviewed the literature on gestational effects on pharmacokinetics of older and newer antiepileptic drugs (AEDs). Absorption, distribution, metabolism, and elimination may be affected depending on the type of AED. A pronounced decline in serum concentrations is seen for AEDs eliminated by glucuronidation (UGT), especially lamotrigine. Serum levels of AEDs cleared mainly through the kidneys, e.g. levetiracetam, decline significantly. In contrast, carbamazepine is affected only marginally by pregnancy. Data on newer drugs are either lacking or vary widely: pregabalin, lacosamide, retigabine, and eslicarbazepine acetate. In general, declining serum concentrations in pregnancy are associated with deterioration in seizure control. AED serum monitoring and dose adjustment based on falling levels may be important, particularly when a patient’s levels are titrated to the lowest effective AED dose and serum concentration before pregnancy. 
COMMENT. Pharmacokinetic changes during pregnancy are rapid and labile and have a profound effect on the management of epilepsy. The risks of uncontrolled seizures are weighed against potential teratogenic effects of AEDs.