Therapeutic drug monitoring of levetiracetam in daily clinical practice: high-performance liquid chromatography versus immunoassay

Determination of Antiepileptics in Biological Samples-A Review

Epilepsy remains a disease that affects many people around the world. With the development of new drugs to treat this condition, the importance of therapeutic drug monitoring continues to rise and remains a challenge for the medical community. This review article explores recent advances in the detection of antiepileptic drugs across various sample types commonly used for drug monitoring, with a focus on their applications and impact. Some of these new methods have proven to be simpler, greener, and faster, making them easier to apply in the context of therapeutic drug monitoring. Additionally, besides the classic use of blood and its derivatives, there has been significant research into the application of alternative matrices due to their ease of sample collection and capacity to reflect drug behavior in blood. These advances have contributed to increasing the efficacy of therapeutic drug monitoring while enhancing its accessibility to the population.

Safety and efficacy of levetiracetam and carbamazepine monotherapy in the management of pediatric focal epilepsy: a randomized clinical trial

Due to the limited number of studies in children with focal epilepsy and the importance of choosing the most suitable drug to control seizures in children, the administration of the most effective medication with the most negligible adverse events is vital. This study aimed to evaluate the effectiveness and adverse events of carbamazepine vs. levetiracetam monotherapy in children with focal seizures. A monocentric, randomized, controlled, double-blind, parallel-group clinical trial was designed. This study was approved by the Iranian Registry of Clinical Trials (registration number: IRCT20170216032603N2) on June 19, 2020, and conducted at the neurology department of Imam Ali Hospital, Karaj, Iran, from February 2020 to March 2021. This study assessed 120 patients with recently diagnosed focal seizures aged 2 to 14. Patients were randomly divided into two groups, who received carbamazepine (CBZ) 15 to 20 mg/kg and levetiracetam (LEV) 20 to 40 mg/kg daily, respectively. Patients were evaluated for improvement and complications at weeks 4, 12, and 24. Out of 120 patients included in the study, six patients were excluded due to various complications of CBZ. The mean number of seizures at the end of the fourth, twelfth, and twenty-fourth weeks were 1.09 ± 0.75, 0.62 ± 0.27, and 0.39 ± 0.12 in the carbamazepine group and 1.11 ± 0.63, 0.52 ± 0.21, and 0.37 ± 0.11 in the LEV group, respectively (P > 0.05). Similarly, the number of seizure-free patients was 34, 44, and 48 in the CBZ group compared to 41, 50, and 54 in the LEV group, respectively (P > 0.05). On the other hand, the frequency of somnolence, dermatologic complications, and agitation was considerably higher in the CBZ group (P < 0.05). Although both medicines were equally effective in seizure control, CBZ was associated with considerably more adverse events and less patient compliance. Physicians should be aware of this difference to prevent unwanted consequences.

Overview of therapeutic drug monitoring and clinical practice

With the rapid development of clinical pharmacy in China, therapeutic drug monitoring (TDM) has become an essential tool for guiding rational clinical drug use and is widely concerned. TDM is a tool that combines pharmacokinetic and pharmacodynamic knowledge to optimize personalized drug therapy, which can improve treatment outcomes, reduce drug-drug toxicity, and avoid the risk of developing drug resistance. To effectively implement TDM, accurate and sophisticated analytical methods are required. By researching the literature published in recent years, we summarize the types of commonly monitored drugs, therapeutic windows, and clinical assays and track the trends and hot spots of therapeutic drug monitoring. The purpose is to provide guidelines for clinical blood drug concentration monitoring, to implement individualized drug delivery programs better, to ensure the rational use of drugs for patients, and to provide a reference for the group to carry out related topics in the future.

Levetiracetam Interaction with Direct Oral Anticoagulants: A Pharmacovigilance Study

BACKGROUND

Levetiracetam is widely used in post-stroke epilepsy. However, it is suspected to possess P-glycoprotein (P-gp) induction properties, and therefore, a potentially significant interaction with direct oral anticoagulants (DOACs). We aimed to search for ischemic stroke signals with levetiracetam and the DOACs.

METHODS

In this retrospective pharmacovigilance study, we used the FAERS database to identify ischemic stroke events associated with DOACs and concomitant use of levetiracetam. We evaluated disproportionate reporting by the adjusted reporting odds ratio (adjROR) and the lower bound of the shrinkage 95% confidence interval. When shrinkage is positive, an increased risk of a specific adverse event occurrence is emphasized over the sum of the individual risks when these same drugs are used separately.

RESULTS

We identified 1841 (1.5%), 3731 (5.3%), 338 (4.9%), and 1723 (1.3%) ischemic stroke reports with apixaban, dabigatran, edoxaban, and rivaroxaban, respectively. The adjROR of the interaction effect was 3.57 (95% CI 2.81-4.58) between DOACs and levetiracetam. The shrinkage analysis detected an interaction between each of the DOACs and levetiracetam. The logistic model and shrinkage analysis failed to detect an interaction when queried for hemorrhagic stroke. A significant signal in the classical enzyme inducer, carbamazepine, strengthened our results (adjROR; 8.47, 95% CI 5.37-13.36).

CONCLUSIONS

Our study shows a strong signal for the levetiracetam interaction with the DOACs. Our findings suggest implementation of a drug monitoring strategy.

An isotope dilution-liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS)-based candidate reference measurement procedure for the quantification of levetiracetam in human serum and plasma

OBJECTIVES

To develop an isotope dilution-liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based candidate reference measurement procedure (RMP) for levetiracetam quantification in human serum and plasma.

METHODS

Quantitative nuclear magnetic resonance spectroscopy (qNMR) was used to characterize the RMP material to ensure traceability to SI units. To quantify levetiracetam, an LC-MS/MS method was optimized using a C8 column for chromatographic separation following protein-precipitation-based sample preparation. Spiked matrix samples of serum and plasma were used to test selectivity and specificity. Matrix effects were determined by performing a post-column infusion experiment and comparing standard line slopes. Precision and accuracy were evaluated over 5 days. Measurement uncertainty was evaluated according to the Guide to the Expression of Uncertainty in Measurement (GUM).

RESULTS

The RMP was proven to be highly selective and specific with no evidence of a matrix effect, allowing for quantification of levetiracetam within the range of 1.53-90.0 μg/mL. Intermediate precision was <2.2% and repeatability was 1.1-1.7% across all concentrations. The relative mean bias ranged from -2.5% to -0.3% across all levels and matrices within the measuring range. Diluted samples were found with a mean bias ranging from -0.1 to 2.9%. The predefined acceptance criterion for measurement uncertainty was met and determined for individual measurements independently of the concentration level and sample type to be ≤4.0% (k=2).

CONCLUSIONS

We present a novel LC-MS/MS)-based candidate RMP for levetiracetam in human serum and plasma. Its expanded measurement uncertainty of ≤4.0% meets the clinical needs in levetiracetam monitoring. Utilizing qNMR to characterize levetiracetam reference materials allowed metrological traceability to SI units.

Quantification of levetiracetam in plasma and urine and its application to a pharmacokinetic study of traumatic brain injury patients

Background: Levetiracetam is an antiepileptic drug used to prevent or treat seizure in patients with severe traumatic brain injury. This study aimed to develop and validate methodology suitable for measuring levetiracetam concentrations in human plasma and urine. Methods: Plasma or urine (10 μl) samples were spiked with [²H₆]-levetiracetam and processed using an acetonitrile precipitation. ESI-LC-MS/MS was employed for analyte detection. Results: The levetiracetam calibration was linear from 0.1 to 50 mg/l in a combined matrix of plasma and urine. Intra- and inter-assay imprecision and accuracy in plasma were <7.7 and 109%, and in urine were <7.9 and 108%, respectively. Conclusion: The validated method was applied to a pharmacokinetic study of levetiracetam in critically ill patients with severe traumatic brain injury.

Development and evaluation of a simple and easy HPLC-UV system simultaneously suitable for determination of 24 anti-epileptic drugs in plasma

This paper aims to establish a simple and easy HPLC system coupled with UV detector suitable for simultaneous determination of 24 antiepileptic drugs in human plasma. Optimized chromatographic separation was performed on a ZORBAX Eclipse Plus-C18 (4.6 mm×150 mm, 3.5 μm) column with acetonitrile and 5 mM potassium dihydrogen phosphate water solution as mobile phase. 24 antiepileptic drugs were divided into three groups and eluted with different gradient procedures, respectively. The column temperature was maintained at 35 °C and the detection wavelength was set at 210 nm. Plasma was processed with ethyl acetate or acetonitrile. The calibration curves of 24 antiepileptic drugs demonstrated good linearity within the test range (r > 0.996). The intra- and inter-batch precision and accuracy were all less than 15%, while extraction recoveries were in the range of 74.57%∼90.89% with the RSD values less than 15%. The validated methods have been successfully applied to determination of some antiepileptic drugs in rat or patient plasma. Those results indicated that the developed methods were simple and easy, and could be suitable for the determination of 24 antiepileptic drugs in plasma just by changing the gradient elution procedures of mobile phase. This article is protected by copyright. All rights reserved.

A Direct Injection Technique to Improve Biosafety to Analyze Levetiracetam Concentrations in Human Serum and Its Application in Therapeutic Drug Monitoring

BACKGROUND

With the outbreak of COVID-19, it has become very important to improve biosafety measures taken by medical staff. Fewer pretreatment steps correspond to lower chances of infection. The authors established a direct injection technique to analyze levetiracetam (LEV) concentrations in human serum and studied its application in therapeutic drug monitoring.

METHODS

Serum samples were prepared by hollow fiber centrifugal ultrafiltration and the filtrate was directly injected into a ultra-high performance liquid chromatography apparatus (Waters UPLC BEH C18 column: 50 × 2.1 mm, 1.7 μm) for analysis. The mobile phase consisted of acetonitrile and water (8:92) at a flow rate of 1.0 mL/min. The column temperature was maintained at 30°C. The detected wavelength was 210 nm.

RESULTS

A linear relationship was obtained for LEV from 0.625 to 80 mcg/mL (r2 = 0.999). The limit of detection for the analysis of LEV was 0.125 mcg/mL. The analysis time was shortened to 4 minutes. The recovery rate of LEV based on the current method was 96.6%-100.1%, whereas the absolute recovery rate was 93.2%-96.8%. The relative SD of intraday and interday precision was <7.3%. Stability was achieved at room temperature for 24 hours after 3 freeze-thaw cycles and at -80°C for 21 days. The method was successfully applied to determine LEV concentrations in the serum of 19 patients.

CONCLUSIONS

The present method is simple, accurate, and sensitive, and can improve biosafety with the direct injection technique. It is suitable for the analysis of LEV concentrations in therapeutic drug monitoring.

New Methods Used in Pharmacokinetics and Therapeutic Monitoring of the First and Newer Generations of Antiepileptic Drugs (AEDs)

The review presents data from the last few years on bioanalytical methods used in therapeutic drug monitoring (TDM) of the 1st-3rd generation and the newest antiepileptic drug (AEDs) cenobamate in patients with various forms of seizures. Chemical classification, structure, mechanism of action, pharmacokinetic data and therapeutic ranges for total and free fractions and interactions were collected. The primary data on bioanalytical methods for AEDs determination included biological matrices, sample preparation, dried blood spot (DBS) analysis, column resolution, detection method, validation parameters, and clinical utility. In conclusion, the most frequently described method used in AED analysis is the LC-based technique (HPLC, UHPLC, USLC) combined with highly sensitive mass detection or fluorescence detection. However, less sensitive UV is also used. Capillary electrophoresis and gas chromatography have been rarely applied. Besides the precipitation of proteins or LLE, an automatic SPE is often a sample preparation method. Derivatization was also indicated to improve sensitivity and automate the analysis. The usefulness of the methods for TDM was also highlighted.