Development and validation of a liquid chromatography-tandem mass spectrometry method with triple-stage fragmentation to determine levetiracetam in epileptic patient serum and its application in therapeutic drug monitoring

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.

A simple and easy non-derivatization gas chromatography-mass spectrometry method for simultaneous quantification of valproic acid, gabapentin, pregabalin, and vigabatrin in human plasma

Immunoassays are currently not available in commercial kits for the quantification of valproic acid, vigabatrin, pregabalin, and gabapentin, which also cannot suffer the limitations of interferences of substances with similar structures. Chromatography is a good alternative to immunoassay. In this study, a simple and robust non-derivatization gas chromatography-mass spectrometry method for simultaneous determination of the above four drugs in human plasma was developed and validated for therapeutic drug monitoring purposes. This method employed benzoic acid as the internal standard with hydrochloric acid for plasma acidification and ACN for precipitate protein. The supernatant was directly injected into gas chromatography-mass spectrometry for analysis. Good linearity was obtained with linear correlation coefficients of the four analytes of 0.9988-0.9996. Extraction recoveries of valproic acid, vigabatrin, pregabalin, and gabapentin were respectively in the ranges of 91.3%-94.5%, 90.0%-90.9%, 90.0%-92.1%, and 88.0%-92.2% with the relative standard deviation values less than 12.6%. Intra- and inter-batch precision and accuracy, and stability assays were all acceptable. Taken together, the novel method developed in this study provided easy plasma pretreatment, good extraction yield, and high chromatographic resolution, which has been successfully validated through the quantification of valproic acid in the plasma of 46 patients with epilepsy.

Development and Validation of a Highly Sensitive and Rapid LC-MS3 Strategy to Determine Oxcarbazepine and Its Active Metabolite in the Serum of Patients with Epilepsy and Its Application in Therapeutic Drug Monitoring

A sensitive and rapid bioanalytical method based on the LC-triple-stage fragmentation (LC-MS³) strategy on a hybrid triple quadrupole-linear ion trap mass spectrometer in combination with protein precipitation extraction for sample pretreatment has been developed and validated for the simultaneous determination of the antiepileptic drug oxcarbazepine (OXC) and its main active metabolite (MHD) in human serum. The separation was performed on a Waters XBridge BEH C18 column (2.5 µm, 2.1 × 50 mm) in isocratic elution with 0.1% formic acid in water and methanol (50:50, v:v) as the mobile phase. The run time for each sample was 2.0 min. The calibration curves ranging from 25 to 1600 ng/mL for OXC and from 0.5 to 32 μg/mL for MHD showed correlation coefficients (r) better than 0.99. All of the validation data, such as precision, accuracy and other parameters, fit the requirements of the current bioanalytical method validation guidelines. The LC-MS³ method for quantitation of OXC and MHD was compared with the LC-MRM based method. Passing–Bablok regression coefficients and Bland–Altman plots showed that the developed LC–MS³ method is a reliable method for quantitative analysis of OXC and MHD. The proposed LC-MS³ method was successfully applied to determine the serum concentrations of OXC and MHD to support a clinical study.

LAP3 contributes to IFN-γ-induced arginine depletion and malignant transformation of bovine mammary epithelial cells

Background

IFN-γ has been traditionally recognized as an inflammatory cytokine that involves in inflammation and autoimmune diseases. Previously we have shown that sustained IFN-γ induced malignant transformation of bovine mammary epithelial cells (BMECs) via arginine depletion. However, the molecular mechanism underlying this is still unknown.

Methods

In this study, the amino acids contents in BMECs were quantified by a targeted metabolomics method. The acquisition of differentially expressed genes was mined from RNA-seq dataset and analyzed bioinformatically. Quantitative reverse transcription polymerase chain reaction (qRT-PCR), enzyme-linked immunosorbent assay (ELISA), western blotting, and immunohistochemistry (IHC) assay were performed to detect gene mRNA and protein expression levels. CCK-8 and would healing assays were used to detect cell proliferation and migration abilities, respectively. Cell cycle phase alternations were analyzed by flow cytometry.

Results

The targeted metabolomics analysis specifically discovered IFN-γ induced arginine depletion through accelerating arginine catabolism and inhibiting arginine anabolism in BMECs. Transcriptome analysis identified leucine aminopeptidase 3 (LAP3), which was regulated by p38 and ERK MAPKs, to downregulate arginine level through interfering with argininosuccinate synthetase (ASS1) as IFN-γ stimulated. Moreover, LAP3 also contributed to IFN-γ-induced malignant transformation of BMECs by upregulation of HDAC2 (histone deacetylase 2) expression and promotion of cell cycle proteins cyclin A1 and D1 expressions. Arginine supplementation did not affect LAP3 and HDAC2 expressions, but slowed down cell cycle process of malignant BMECs. In clinical samples of patients with breast cancer, LAP3 was confirmed to be upregulated, while ASS1 was downregulated compared with healthy control.

Conclusions

These results demonstrated that LAP3 mediated IFN-γ-induced arginine depletion to malignant transformation of BMECs. Our findings provide a potential therapeutic target for breast cancer both in humans and dairy cows.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09963-w.

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.