Development and validation of a reversed-phase HPLC method for licarbazepine monitoring in serum of patients under oxcarbazepine treatment

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.

Quantification of Oxcarbazepine Using Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)

Oxcarbazepine (Trileptal®) has been found effective in the treatment of tonic-clonic seizures and partial seizures with or without secondary generalization, with fewer side effects than traditional therapy. Oxcarbazepine is a keto analogue of carbamazepine. It is rapidly reduced to 10-monohydroxy carbamazepine (MHD), its active metabolite. This assay measures concentrations for oxcarbazepine metabolite (MHD), internal standard (MHD 13C6) solution is added to all the patient specimens resulting in precipitation of proteins. The analytes are separated using a Phenomenex Kinetex C18 column and are detected with a mass spectrophotometer utilizing multiple reaction monitoring (MRM). The analytes are qualitatively identified and quantitated from a calibration curve generated from calibrators included in the run.

The Effect of Plasma Protein Binding on the Therapeutic Monitoring of Antiseizure Medications

Epilepsy is a widely diffused neurological disorder including a heterogeneous range of syndromes with different aetiology, severity and prognosis. Pharmacological treatments are based on the use, either in mono- or in polytherapy, of antiseizure medications (ASMs), which act at different synaptic levels, generally modifying the excitatory and/or inhibitory response through different action mechanisms. To reduce the risk of adverse effects and drug interactions, ASMs levels should be closely evaluated in biological fluids performing an appropriate Therapeutic Drug Monitoring (TDM). However, many decisions in TDM are based on the determination of the total drug concentration although measurement of the free fraction, which is not bound to plasma proteins, is becoming of ever-increasing importance since it correlates better with pharmacological and toxicological effects. Aim of this work has been to review methodological aspects concerning the evaluation of the free plasmatic fraction of some ASMs, focusing on the effect and the clinical significance that drug-protein binding has in the case of widely used drugs such as valproic acid, phenytoin, perampanel and carbamazepine. Although several validated methodologies are currently available which are effective in separating and quantifying the different forms of a drug, prospective validation studies are undoubtedly needed to better correlate, in real-world clinical contexts, pharmacokinetic monitoring to clinical outcomes.

Review of Chromatographic Methods Coupled with Modern Detection Techniques Applied in the Therapeutic Drugs Monitoring (TDM)

Therapeutic drug monitoring (TDM) is a tool used to integrate pharmacokinetic and pharmacodynamics knowledge to optimize and personalize various drug therapies. The optimization of drug dosing may improve treatment outcomes, reduce toxicity, and reduce the risk of developing drug resistance. To adequately implement TDM, accurate and precise analytical procedures are required. In clinical practice, blood is the most commonly used matrix for TDM; however, less invasive samples, such as dried blood spots or non-invasive saliva samples, are increasingly being used. The choice of sample preparation method, type of column packing, mobile phase composition, and detection method is important to ensure accurate drug measurement and to avoid interference from matrix effects and drug metabolites. Most of the reported procedures used liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) techniques due to its high selectivity and sensitivity. High-performance chromatography with ultraviolet detection (HPLC-UV) methods are also used when a simpler and more cost-effective methodology is desired for clinical monitoring. The application of high-performance chromatography with fluorescence detection (HPLC-FLD) with and without derivatization processes and high-performance chromatography with electrochemical detection (HPLC-ED) techniques for the analysis of various drugs in biological samples for TDM have been described less often. Before chromatographic analysis, samples were pretreated by various procedures-most often by protein precipitation, liquid-liquid extraction, and solid-phase extraction, rarely by microextraction by packed sorbent, dispersive liquid-liquid microextraction. The aim of this article is to review the recent literature (2010-2020) regarding the use of liquid chromatography with various detection techniques for TDM.

Development and validation of an improved HPLC-UV method for simultaneous determination of lamotrigine and oxcarbazepine and its active metabolite 10,11-dihydro-10-hydroxycarbazepine in human blood plasma and comparison with an UHPLC-MS/MS method

Lamotrigine (LTG) and oxcarbazepine (OXC) are first-line drugs for epilepsy treatment. Their large pharmacokinetics variabilities and relations between efficacy and toxicity and blood plasma concentration require routine monitoring for dose adjustment. In this study, we developed and validated a simple, accurate, and reliable method for simultaneous determination of LTG, OXC and 10,11-dihydro-10-hydroxycarbazepine (MHD) in human blood plasma by high-performance liquid chromatography-ultraviolet detection (HPLC-UV) with a simple one-step protein precipitation using methanol (1% acetic acid) and 15 min elution time under isocratic elution at 1 mL/min. Calibration range was 2.4 to 120 mg/L for LTG, OXC, and MHD. The intra-day and inter-day bias were − 8.84 to 4.18%, and the imprecision was less than 8.08% for all analytes. The internal standard (fluconazole) normalized recovery was 96.30 to 107.69% for LTG, 98.51 to 111.04% for MHD, and 95.04 to 109.86% for OXC. A total of 186 LTG samples and 25 MHD samples were used to evaluate the agreement between HPLC-UV and ultra-performance liquid chromatography-mass spectrometry (UHPLC-MS/MS) by Passing-Bablok regression and Bland-Altman plot. The mean bias and the 95% limits of agreement (95% LOA) of the two measurements were 0.575 mg/L and − 1.238 to 2.387 mg/L for LTG (n = 186) and − 1.222 mg/L and − 8.271 to 5.827 mg/L for MHD (n = 25), which indicated the UV method was comparable with the MS method for LTG and MHD analysis.

Optical Biosensors for Therapeutic Drug Monitoring

Therapeutic drug monitoring (TDM) is a fundamental tool when administering drugs that have a limited dosage or high toxicity, which could endanger the lives of patients. To carry out this monitoring, one can use different biological fluids, including blood, plasma, serum, and urine, among others. The help of specialized methodologies for TDM will allow for the pharmacodynamic and pharmacokinetic analysis of drugs and help adjust the dose before or during their administration. Techniques that are more versatile and label free for the rapid quantification of drugs employ biosensors, devices that consist of one element for biological recognition coupled to a signal transducer. Among biosensors are those of the optical biosensor type, which have been used for the quantification of different molecules of clinical interest, such as antibiotics, anticonvulsants, anti-cancer drugs, and heart failure. This review presents an overview of TDM at the global level considering various aspects and clinical applications. In addition, we review the contributions of optical biosensors to TDM.

Development of an online solid-phase extraction-liquid chromatography-mass spectrometric analysis of oxcarbazepine and its active metabolite licarbazepine from plasma with a direct injection step

We developed an online solid phase extraction procedure using a hydrophilic-lipophilic balance sorbent, with reversed-phase liquid chromatography-high-resolution mass spectroscopy for the determination of oxcarbazepine and its active metabolite licarbazepine in plasma samples. The analytes were detected using a high-resolution Q Orbitrap mass spectrometer with targeted-selected ion monitoring (t-SIM) in positive scan mode. Under the optimized conditions, the method was linear with R² values >0.99. The method was linear from 0.008 to 2.000 μg mL^-1 and the lower limit of quantification was 0.008 μg mL^-1 for both oxcarbazepine and licarbazepine. Recoveries ranged from 92.34 to 104.27% and from matrix-matched samples from 94.26 to 104.19%. The intraday and interday precision RSD values were <9.13% with an associated accuracy of 92.71 to 104.06%. The total time for the one step online procedure was only 8 min. This method provides a direct and accurate measurement for therapeutic drug monitoring of oxcarbazepine and its active metabolite licarbazepine.