Association of oxcarbazepine concentration with seizure frequency in pregnant women with epilepsy

The management of epilepsy during pregnancy presents particular challenges for neurologists worldwide. Currently, there are no clear recommendations for oxcarbazepine (OXC) specific target concentration during pregnancy. We conducted this retrospective observational cohort study on pregnant women with epilepsy (WWE) who received OXC monotherapy or polytherapy, at the epilepsy outpatient clinic of a tertiary hospital in eastern China. Sixteen pregnancies of 16 WWE were split into the seizure-free group or the non-seizure-free group, according to whether they had been seizure free for more than one year prior to conception or not. There was a significantly decrease in OXC concentration throughout pregnancy, as indicated by the concentration/dose ratio and the ratio of target concentration (RTC). The second trimester of pregnancy was the period when seizure deterioration occurred the most, particularly in the non-seizure-free group. Lower RTC_OXC was identified to be a risk factor for increasing seizure frequency in both the total group and the non-seizure-free group in both univariate and multivariate analysis, with a threshold of 0.575 for differentiating patients at high-risk and low-risk for seizure deterioration. In conclusion, this study suggested an OXC concentration threshold of 0.575 during pregnancy for assisting neurologists in OXC drug monitoring and dose adaptation.