Serum concentration/dose ratio of levetiracetam before, during and after pregnancy

PURPOSE To investigate changes in levetiracetam (LEV) serum concentration/dose ratio (C/D-ratio) in relation to pregnancy. METHODS Altogether 21 consecutive pregnancies in 20 women with epilepsy receiving LEV during gestation were studied retrospectively. The main target variable was the C/D-ratio before and during pregnancy, and in the post partum period. Secondary target variables were changes in LEV dose, concomitant use of other antiepileptic drugs and seizure frequency. Student's paired t-test and two-sample t-test for independent samples were used to test for statistically significant changes in C/D-ratio means. RESULTS Mean C/D-ratio in the third trimester was 50% of the mean C/D-ratio at baseline (p<0.001, n=11). Baseline levels were reached within the first weeks after pregnancy. The interindividual variability was pronounced. CONCLUSIONS Serum concentrations of LEV declined significantly in the third trimester of pregnancy and increased rapidly after delivery.