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

Population pharmacokinetics of levetiracetam in Chinese adult epilepsy patients with varying renal function: exposure simulation and individualized dosing adjustments

Levetiracetam (LEV) has become a first-line treatment option for various types of epilepsy with a broad spectrum of efficacy and favorable pharmacokinetic profile. We aimed to develop a population pharmacokinetic (PPK) model for LEV and devise a model-based dosing guideline specific to Chinese adult epilepsy patients. Employing Phoenix NLME 7.0 software, we utilized the first-order conditional estimation and extended least squares method to establish the PPK model. The PK of LEV was effectively characterized using a one-compartment model. Monte Carlo simulations were then performed to generate dosing guidelines suitable for various patient groups. The Bayesian feedback method was employed to develop the clinical individual predictive model. Data from 80 Chinese adult patients yielded 148 LEV plasma concentrations for analysis. In the final model, the absorption rate constant was fixed at 2.44. The apparent volume of distribution and the apparent clearance (CL/F) had population typical values of 35.34 L and 3.24 L/h, respectively. CL/F of LEV was significantly influenced by creatinine clearance (CrCL), identified as a major covariate. Monte Carlo simulations indicated that regimens of 0.5 g, 0.75 g, 1.0 g, 1.5 g, 2.0 g, 2.5 g, and 3.5 g twice daily were associated with the highest probability of target attainment (PTA) in patients with different renal function levels. Accordingly, a user-friendly dose recommendation was formulated for these patients. The individual predictive model accurately matched the observed concentrations and managed to guide the personalized dose adjustment. The PPK model linked CL/F to CrCL. Model-based simulations suggest that higher dosage adjustments may be necessary for those with augmented renal function. The developed clinical individual predictive model could effectively guide personalized dose adjustments, potentially reducing the need for frequent drug concentration measurements.

Optimizing drug therapy during pregnancy: a spotlight on population pharmacokinetic modeling

INTRODUCTION

Optimizing drug therapy during pregnancy is crucial for ensuring the safety of mothers and babiesPhysiological changes that occur during pregnancy can significantly alter the pharmacokinetics of medications. Population pharmacokinetic (PopPK) modeling is a valuable tool to guide drug dosing regimens in pregnant women.

AREAS COVERED

This narrative review summarizes the current literature on the application of PopPK modeling to optimize drug therapy during human pregnancy. It provides an overview of the physiological changes affecting drug disposition in pregnancy and the basic concepts of PopPK modeling including structural, stochastic, and covariate models. We have conducted an exhaustive literature search (PubMed, Web of Science) spanning May 2014-May 2024 to identify PopPK models in the pregnant population. We have highlighted strategies for model building, evaluation, and interpretation with a focus on identifying clinically relevant covariates that inform dose individualization. Case studies illustrating the utility of PopPK models in guiding dosing recommendations for specific drugs are discussed.

EXPERT OPINION

Covariate identification can lead to improved mechanistic understanding of drug disposition and establishment of improved dosing regimens during pregnancy. Insufficient data across trimesters may limit the ability of PopPK models to capture time-varying gestational effects.

Influence of CYP2C8*3 and ABCG2 C421A genetic polymorphisms on trough concentration and molecular response of imatinib in Egyptian patients with chronic myeloid leukemia

PURPOSE

The treatment landscape for chronic myeloid leukemia (CML) has been revolutionized by the introduction of imatinib, a tyrosine kinase inhibitor, which has transformed the disease from a fatal condition into a manageable chronic illness for a substantial number of patients. Despite this, some individuals do not respond adequately to the treatment, and others may experience disease progression even with continued therapy. This study examined how CYP2C8*3 (G416A; rs11572080) and ABCG2 C421A (rs2231142) single nucleotide polymorphisms (SNPs) affect the plasma trough concentration and therapeutic response of imatinib in Egyptian CML patients.

METHODS

The study included fifty patients with chronic-phase CML, who were categorized into two groups: responders (n = 26) and non-responders (n = 24), according to their BCR-ABL1 transcription levels after 12 months of imatinib treatment. Genotyping of the CYP2C8*3 and ABCG2 C421A polymorphisms was performed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), while plasma trough concentrations were determined through high-performance liquid chromatography with ultraviolet-diode array detection (HPLC-UV/DAD).

RESULTS

Patients with the CA genotype of ABCG2 C421A showed significantly higher mean plasma trough concentrations of imatinib (CA: 1731 ± 424.7 ng/mL; CC: 1294 ± 381.3 ng/mL; p = 0.0132) and demonstrated a better molecular response compared to those with the CC genotype (p = 0.0395).

CONCLUSION

The ABCG2 C421A polymorphism significantly influenced imatinib plasma trough concentrations and molecular responses in Egyptian chronic-phase CML patients. Genotyping of this polymorphism in these patients could assist in optimizing imatinib therapy, predicting more favorable treatment outcomes, and enabling the development of more personalized treatment plans.

Adaptive Dosage Strategy of Levetiracetam in Chinese Epileptic Patients: Focus on Pregnant Women

There is presently no efficient dose individualization strategy for the use of antiseizure medications in epileptic pregnant patients. This study aimed to develop a population pharmacokinetics model for levetiracetam and propose a tailored adaptive individualized dosage strategy for epileptic pregnant patients. A total of 322 levetiracetam plasma concentrations from 238 patients with epilepsy were included, including 216 women with epilepsy (20.83% of whom were pregnant). The levetiracetam plasma concentration was measured using a validated ultra-performance liquid chromatography-tandem mass spectrometry assay, and the data were modeled using a nonlinear mixed-effects model. The resultant model served as the basis for simulating the dosage adjustment strategy. A one-compartment model with first-order elimination best described the pharmacokinetic data of levetiracetam. The apparent clearance (CL/F) was 3.43 L/h (95% CI 3.30-3.56) and the apparent volume of distribution was 43.7 L (95% CI 40.4-47.0) for a typical individual of 57.2 kg. Pregnancy and body weight were found to be significant covariates of CL/F of levetiracetam. The recommended regimen of levetiracetam could be predicted by the population pharmacokinetic model based on body weight, gestational age, and the daily dose of levetiracetam taken before pregnancy.

Therapeutic drug monitoring in pregnancy: Levetiracetam

OBJECTIVE

Levetiracetam (LEV) is an antiseizure medication that is mainly excreted by the kidneys. Due to its low teratogenic risk, LEV is frequently prescribed for women with epilepsy (WWE). Physiological changes during gestation affect the pharmacokinetic characteristics of LEV. The goal of our study was to characterize the changes in LEV clearance during pregnancy and the postpartum period, to better plan an LEV dosing paradigm for pregnant women.

METHODS

This retrospective observational study incorporated a cohort of women who were followed up at the epilepsy in pregnancy clinic at Tel Aviv Sourasky Medical Center during the years 2020-2023. Individualized target concentrations of LEV and an empirical postpartum taper were used for seizure control and to reduce toxicity likelihood. Patient visits took place every 1-2 months and included a review of medication dosage, trough LEV blood levels, week of gestation and LEV dose at the time of level measurement, and seizure diaries. Total LEV concentration/dose was calculated based on LEV levels and dose as an estimation of LEV clearance.

RESULTS

A total of 263 samples were collected from 38 pregnant patients. We observed a decrease in LEV concentration/dose (C/D) as the pregnancy progressed, followed by an abrupt postpartum increase. Compared to the 3rd trimester, the most significant C/D decrease was observed at the 1st trimester (slope = .85), with no significant change in the 2nd trimester (slope = .11). A significant increase in C/D occurred postpartum (slope = 5.23). LEV dose was gradually increased by 75% during pregnancy compared to preconception. Average serum levels (μg/mL) decreased during pregnancy. During the postpartum period, serum levels increased, whereas the LEV dose was decreased by 24%, compared to the 3rd trimester.

SIGNIFICANCE

LEV serum level monitoring is essential for WWE prior to and during pregnancy as well as postpartum. Our data contribute to determining a rational treatment and dosing paradigm for LEV use during both pregnancy and the postpartum period.

Quantitation of levetiracetam concentrations in plasma and saliva samples by ultra-performance liquid chromatography-tandem mass spectrometry: Application to therapeutic drug monitoring for pregnant women with epilepsy

Although levetiracetam (LEV) has favorable linear pharmacokinetic properties, therapeutic drug monitoring (TDM) is necessary for pregnant women with epilepsy. This study aims to build a simple, reliable, and sensitive ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for determining LEV concentrations in plasma and saliva samples, to support the routine TDM of LEV in Chinese pregnant women with epilepsy. The stable isotope-labeled LEV-d6 was used as the internal standard. The extracted samples were analyzed using a UPLC-MS/MS system with positive electrospray ionization. Mobile phase A was water containing 5 mM ammonium acetate and 0.1% formic acid, and phase B was 1:1 methanol-acetonitrile with 0.1% formic acid. The method was validated and utilized to determine LEV concentrations in non-pregnant and pregnant patients with epilepsy. The developed method was validated in both plasma and saliva samples over a concentration range of 0.1-50 μg/mL. The intra- and inter-batch accuracy for LEV ranged from -7.0% to 2.9%, with precisions between 2.7% and 9.3%. In pregnant patients, the mean dose-standardized LEV trough plasma concentrations were significantly lower than those in non-pregnant patients (4.73 ± 2.99 vs. 7.74 ± 3.59 ng/mL per mg/day; P < 0.0001). It is recommended that the TDM of LEV should be routinely performed during the different stages of pregnancy.