Determination of clozapine and norclozapine in dried plasma spot and dried blood spot by liquid chromatography-tandem mass spectrometry

Fabrication of a molecularly imprinted polymer-based electrochemical sensor for the selective assay of antipsychotic drug clozapine and performance comparison with LC-MS/MS

Clozapine (CLO) is an atypical antipsychotic drug indicated for the treatment of schizophrenia. The treatment effectiveness of CLO is better than that of other atypical antipsychotics, and it has the advantage of being able to determine its effectiveness by measuring its concentration in the patient's blood. Thus, sensitive, selective, and accurate determination of CLO in blood is highly significant for treatment monitoring. This study describes the design and fabrication of a molecularly imprinted polymer (MIP)-based electrochemical sensor for CLO determination. This is the first MIP-based electrochemical application in the literature for CLO determination. Employing the thermal polymerization approach, the MIP was formed on the glassy carbon electrode (GCE) using CLO as the template, trans-3-(3-Pyridyl)acrylic acid (3,3-TA) as the functional monomer, and the support of zinc oxide nanoparticles (ZnO NPs). Elaborate characterizations in terms of surface morphology and electrochemistry were performed via scanning electron microscopy (SEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) methods. An indirect approach was employed to determine CLO in standard solution, real human biological samples, and tablet formulation, using 5 × 10-3 M [Fe(CN)6]3-/4- solution as the redox probe. The limit of detection (LOD) values for the standard solution and serum sample were calculated as 2.9 × 10-11 M and 6.01 × 10-12 M, respectively. These values and recovery studies confirmed the sensor's sensitivity and feasibility. The measurements in the presence of similarly structured compounds (olanzapine and quetiapine fumarate) verified the sensor's superior selectivity. Moreover, the developed sensor's performance was compared and verified using an LC-MS/MS method using the student's t-test and F-test.

Application of a Novel UPLC-MS/MS Method for Analysis of Rivaroxaban Concentrations in Dried Blood Spot and Plasma Samples Collected from Patients with Venous Thrombosis

Despite a higher safety profile compared to vitamin K antagonists, rivaroxaban therapy is still connected with multiple adverse effects, such as a high risk of bleeding. Thus, therapeutic drug monitoring (TDM) of rivaroxaban concentrations is suggested. An alternative to plasma samples can be dried blood spots (DBS), which minimize the cost of sample storage and transport. In this study, we developed a UPLC-MS/MS method for the analysis of rivaroxaban in DBS and plasma samples. Chromatographic separation was achieved on a Zorbax Eclipse Plus C18 column (2.1 × 100 mm; 3.5 µm, Agilent Technologies Inc., Santa Clara, CA, USA) with a mobile phase consisting of water and acetonitrile, both containing 0.1% formic acid. The analytes were detected using a positive ionization mode by multiple reaction monitoring. We validated the method according to ICH guidelines. The precision and accuracy were satisfactory. Extraction recovery was approximately 57% and 66% for DBS and plasma samples, respectively. A high correlation between rivaroxaban concentrations in plasma and DBS samples collected from patients was confirmed with Deming regression. The suitability of both sampling techniques for the rivaroxaban TDM was also verified by Bland-Altman plots based on DBS-predicted and observed plasma concentrations. In addition, we found a significant relationship between rivaroxaban concentrations and coagulation parameters, including prothrombin time (PT) and international normalized ratio (INR).

Analytical Methods for Determining Psychoactive Substances in Various Matrices: A Review

Psychoactive substances pose significant challenges and dangers to society due to their impact on perception, mood, and behavior, leading to health and life disturbances. The consumption of these substances is largely influenced by their legal status, cultural norms, and religious beliefs. Continuous development and chemical modifications of psychoactive substances complicate their control, detection, and determination in the human body. This paper addresses the terminological distinctions between psychoactive and psychotropic substances and drugs. It provides a comprehensive review of analytical methods used to identify and quantify 25 psychoactive substances in various biological matrices, including blood, urine, saliva, hair, and nails. The analysis categorizes these substances into four primary groups: stimulants, neuroleptics, depressants, and hallucinogens. The study specifically focuses on chromatographic and spectrophotometric methods, as well as other novel analytical techniques. Methodology includes a review of scientific articles containing validation studies of these methods and innovative approaches to psychoactive substance determination. Articles were sourced from the PubMed database, with most research originating from the twenty first century. The paper discusses the limits of detection and quantitation for each method, along with current trends and challenges in the analytical determination of evolving psychoactive substances.

Microsampling Techniques Suitable for Therapeutic Drug Monitoring of Antipsychotics

BACKGROUND

Therapeutic drug monitoring (TDM) of antipsychotics for dose titration or detection of noncompliance is not uncommon in daily practice. Normally, TDM implies measuring a drug concentration in venous blood samples. This technique is invasive and requires trained assistants and patients normally need to go to an outpatient clinic. Over the past decades, sensitivity of analytical equipment has improved leading to a growing interest in microsampling techniques. These techniques are minimally invasive, require a small volume (<100 μL), usually result in stable samples, and can be collected by the patient or a caregiver at home. Before a microsampling technique can be used in daily routine, proper method development and a clinical validation study should be performed.

METHOD

For this review, the databases of PubMed and Embase were systematically searched. Currently available microsampling techniques for antipsychotics in blood, serum, or plasma are summarized. Subsequently, it has also been assessed whether these techniques are sufficiently validated for TDM monitoring in daily practice.

RESULTS

Several microsampling techniques are available today, for example, dried blood spot sampling, dried plasma extraction cards, and volumetric absorptive microsampling. Eighteen studies were identified in which a microsampling technique for 1 or a few antipsychotics was chemically analytically and clinically validated. However, the majority of these studies have relevant shortcomings that mean its usefulness for different antipsychotics is not yet well established.

CONCLUSIONS

Microsampling for TDM can be recommended for patients using clozapine. For TDM of other antipsychotics, it is a very promising development.

Chromatographic Methods for the Analysis of the Antipsychotic Drug Clozapine and Its Major Metabolites: A Review

Clozapine (CLZ), a second-generation antipsychotic, can effectively reduce schizophrenia, bipolar disorder and major depression symptoms. This review provides an overview of all reported chromatographic methods (62 references) for the quantification of CLZ and its two main metabolites, norclozapine and clozapine N-oxide in pharmaceutical formulations, biological matrices and environmental samples.

Therapeutic drug monitoring of clozapine in human serum by high-throughput paper spray mass spectrometry

Introduction

Monitoring the atypical antipsychotic drug clozapine is crucial to ensure patient safety. This article showcases a high-throughput analytical method for measuring clozapine and its primary metabolite norclozapine (N-desmethylclozapine) in serum using paper spray mass spectrometry (PS-MS).

Objectives

This study aimed to assess the viability of a PS-MS method for the rapid measurement of clozapine and norclozapine in human serum samples as an alternative to liquid chromatography mass spectrometry (LC-MS).

Methods

Serum samples were processed by protein precipitation followed by deposition of the supernatant containing labelled internal standards onto paper spray substrates mounted in cartridges. Analytes were then analyzed using a triple quadrupole mass spectrometer equipped with a commercial paper spray ionization source. The results obtained from the patient samples were compared to those from a validated LC-MS assay.

Results

PS-MS calibrations for clozapine and norclozapine were linear (R2 > 0.99) over five days. Between-run precision was below 8 %, and within-run precision did not exceed 10 %. When compared to a validated LC-MS method, the mean bias for 39 patient samples was -9% for clozapine and -1% for norclozapine, with no outliers. Mass spectrometry ion ratio comparisons indicated no interference for patient samples above the lower limit of quantification. There was less than 7 % change in the measured concentrations of both analytes over five days for samples dried on paper substrates. Notably, virtually no maintenance of the MS source was required during this study.

Conclusion

This study illustrates the potential of PS-MS for serum drug monitoring in the clinical laboratory.

Revolutionizing Blood Collection: Innovations, Applications, and the Potential of Microsampling Technologies for Monitoring Metabolites and Lipids

Blood serves as the primary global biological matrix for health surveillance, disease diagnosis, and response to drug treatment, holding significant promise for personalized medicine. The diverse array of lipids and metabolites in the blood provides a snapshot of both physiological and pathological processes, with many routinely monitored during conventional wellness checks. The conventional method involves intravenous blood collection, extracting a few milliliters via venipuncture, a technique limited to clinical settings due to its dependence on trained personnel. Microsampling methods have evolved to be less invasive (collecting ≤150 µL of capillary blood), user-friendly (enabling self-collection), and suitable for remote collection in longitudinal studies. Dried blood spot (DBS), a pioneering microsampling technique, dominates clinical and research domains. Recent advancements in device technology address critical limitations of classical DBS, specifically variations in hematocrit and volume. This review presents a comprehensive overview of state-of-the-art microsampling devices, emphasizing their applications and potential for monitoring metabolites and lipids in blood. The scope extends to diverse areas, encompassing population studies, nutritional investigations, drug discovery, sports medicine, and multi-omics research.

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.

Blood microsampling technologies: Innovations and applications in 2022

With the development of highly sensitive bioanalytical techniques, the volume of samples necessary for accurate analysis has reduced. Microsampling, the process of obtaining small amounts of blood, has thus gained popularity as it offers minimal-invasiveness, reduced logistical costs and biohazard risks while simultaneously showing increased sample stability and a potential for the decentralization of the approach and at-home self-sampling. Although the benefits of microsampling have been recognised, its adoption in clinical practice has been slow. Several microsampling technologies and devices are currently available and employed in research studies for various biomedical applications. This review provides an overview of the state-of-the-art in microsampling technology with a focus on the latest developments and advancements in the field of microsampling. Research published in the year 2022, including studies (i) developing strategies for the quantitation of analytes in microsamples and (ii) bridging and comparing the interchangeability between matrices and choice of technology for a given application, is reviewed to assess the advantages, challenges and limitations of the current state of microsampling. Successful implementation of microsampling in routine clinical care requires continued efforts for standardization and harmonization. Microsampling has been shown to facilitate data-rich studies and a patient-centric approach to healthcare and is foreseen to play a central role in the future digital revolution of healthcare through continuous monitoring to improve the quality of life.