Population pharmacokinetics and dosing regimen optimization of levetiracetam in epilepsy during pregnancy

Aims The pharmacokinetics of levetiracetam (LEV) significantly changed during pregnancy. It is a great challenge to predict the adjusted doses of LEV to reach the preconception target concentrations. This study aimed to establish a population pharmacokinetic model of LEV in women with epilepsy (WWE) during pregnancy to analyse the factors of pharmacokinetic variability and to develop a model‐based individualized dosing regimen. Methods A total of 166 concentration–time points from 37 WWE during pregnancy treated with LEV were collected to analyse LEV pharmacokinetics with nonlinear mixed‐effects modelling. The dosing regimen was optimized by Monte Carlo simulations based on the final model. Results The LEV pharmacokinetics in pregnant WWE were best described by a 1‐compartment model of first‐order absorption and elimination. The population typical value of apparent clearance (CL/F) in the final model was estimated to be 3.82 L/h (95% confidence interval 3.283–4.357 L/h) with a relative standard error of 7.2%. Both total body weight (TBW) and trimester of pregnancy were significantly associated with LEV‐CL/F during pregnancy; LEV‐CL/F increased by 42.72% when TBW increased from 55 to 65 kg from the first trimester to the second trimester. Monte Carlo simulations showed that dosing regimens for LEV should be individualized based on the patient's TBW and trimester of pregnancy to maximize the likelihood of achieving the therapeutic range. Conclusion This first population pharmacokinetic study of LEV in WWE during pregnancy supports the use of a weight‐based and pregnancy‐based dosing regimen and can lay a foundation for further optimizing the individualized dosing regimens.