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Biochemical testing in urine is a powerful new tool in the investigation of non-adherence to cardiovascular medications Drug testing using liquid chromatography tandem mass spectrometry (LC-MS-MS) is the mainstay of the laboratory test but may be subject to pre-analytical factors that could impact on test results. The stability of cardiovascular medications in urine is one such factor that has not been fully explored in non-adherence testing and has the potential to result in patients appearing falsely non-adherent to their therapy. The stability of 29 cardiovascular medications in patients' urine samples were assessed at room temperature (RT) and at -80°C using a LC-MS-MS screening method. All drugs and drug metabolites were found to be stable under the storage conditions studied. The findings imply that the medication stability in urine samples does not have any impact on non-adherence results and thus allowing samples to be taken and transported without the need for specialist sample handling procedures. The stability of cardiovascular drugs in urine samples will allow adherence testing to be utilized more widely into routine clinics and research., (© The Author(s) 2018. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Meldonium is a metabolic drug whose inclusion in the 2016 List of Prohibited Substances and Methods followed the analysis of data collected under the 2015 World Anti-Doping Agency Monitoring Program. In the early months of 2016, anti-doping laboratories reported an unusually high number of cases in which urine samples contained high concentrations of meldonium. Consequently, the meldonium excretion period in healthy athletes and the substance's long-term urine and blood (plasma) pharmacokinetics became central questions for the anti-doping community to address, to ensure appropriate assessment of the scientific and medical situation, and also fair treatment of athletes from a result management and legal standpoint. At the present time, data on meldonium pharmacokinetics is limited to a few studies, with no known data available on long-term excretion of high oral doses. The primary objective of this open-label study was to determine long-term urine and plasma pharmacokinetic parameters of meldonium in healthy volunteers. Study design included single and repeated functional load testing and assessment of L-carnitine administration on meldonium excretion and pharmacokinetics. Thirty-two volunteers were equally divided into two groups receiving either 1.0 g or 2.0 g of oral meldonium daily for 3 weeks. The study found meldonium takes several days to attain a steady state in blood and displays an elimination period over several months after cessation of treatment. Moreover, findings demonstrate that the daily dose, periodicity and duration of treatment with meldonium are the most important factors to consider in calculating the substance's elimination and complete body clearance., (© 2018 John Wiley & Sons, Ltd.)

In the last few years, a number of studies were conducted which aimed at understanding the mechanisms of cardiovascular drug, metabolism, and there is still the need to determine the metabolites of cardiac drugs for the purpose of metabolism control. In this study, we employ a direct combination of electrochemical oxidation and mass spectrometric (EC-MS) identification for monitoring the oxidation pathway of ten cardiovascular drugs (metoprolol, propranolol, propafenone, mexiletine, oxprenolol, pirbuterol, pindolol, cicloprolol, acebutolol and atenolol). Oxidation was accomplished in an electrochemical thin-layer cell coupled on-line to electrospray ionization mass spectrometry (EC/ESI-MS). For further characterization of electrochemical products, the approach involving liquid chromatography linked to tandem mass spectrometry was used. Appropriate conditions for oxidation and identification processes with such parameters as the potential value, mobile phase (type and pH) and working electrode were optimized. Optimization was performed with the use of central composite design (CCD). Besides electrochemical oxidation of analytes (phase I of metabolic transformation), addition of glutathione (GSH) for follow-up reactions (phase II conjunction) was also investigated. The electrochemical results were compared to in-vivo experiments by analyzing plasma and urine samples from patients who had been administered selected cardiovascular drugs. These results show that electrochemistry coupled to mass spectrometry turned out to be an analytical tool suitable to procure a feasible analytical base for the envisioned in vivo experiments., (Copyright © 2017 Elsevier B.V. All rights reserved.)

An effective dual preconcentration method involving off-line membrane supported liquid-liquid-liquid microextraction (MS-LLLME) and on-line field-amplified sample injection (FASI) was proposed for the extraction of six cardiovascular drugs, including mexiletine, xylocaine, propafenone, propranolol, metoprolol, and carvedilol from aqueous solution prior to CE-UV. In MS-LLLME, the analytes were extracted from 9 mL sample solution into toluene, and then back extracted into a drop of acceptor phase of 10 μL 20 mmol/L acetic acid. After that, the acceptor phase was directly introduced into CE for FASI without any modification. In FASI process, water plug was hydrodynamically injected (50 mbar, 3 s) into the capillary prior to sample injection (+6 kV, 18 s). Six target analytes were separated in less than 10 min at 25°C with a BGE consisting of 70 mmol/L Tris-H3 PO4 (pH 2.2) containing 10% v/v methanol. Under the optimized conditions, LODs obtained by the proposed MS-LLLME-FASI-CE-UV method were in the range of 0.02-0.82 μg/L (based on S/N = 3) with enrichment factors of 546- to 7300-fold for the target analytes. The RSDs of the developed method were in the range of 6.7-12.9% (n = 7). Good linearity (R(2) = 0.9928-0.9997) was obtained in concentration range of 0.1-100 μg/L for mexiletine and propranolol, 0.2-100 μg/L for xylocaine and metoprolol, 0.5-100 μg/L for propafenone and 2.0-100 μg/L for carvedilol, respectively. The developed method was successfully applied for real-time determination of metoprolol in human urine samples within 26 h after uptake., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

LC-high resolution (HR)-MS well established in proteomics has become more and more important in bioanalysis of small molecules over the last few years. Its high selectivity and specificity provide best prerequisites for its use in broad screening approaches. Therefore, Orbitrap technology was tested for developing a general metabolite-based LC-HR-MS/MS screening approach for urinalysis of drugs necessary in clinical and forensic toxicology. After simple urine precipitation, the drugs and their metabolites were separated within 10 min and detected by a Q-Exactive mass spectrometer in full scan with positive/negative switching, and subsequent data dependent acquisition (DDA) mode. Identification criteria were the presence of accurate precursor ions, isotopic patterns, five most intense fragment ions, and comparison with full HR-MS/MS library spectra. The current library contains over 1900 parent drugs and 1200 metabolites. The method was validated for typical drug representatives and metabolites concerning recovery, matrix effects, process efficiency, and limits showed acceptable results. The applicability was tested first for cardiovascular drugs, which should be screened for in poisoning cases and for medication adherence of hypertension patients. The novel LC-HR-MS/MS method allowed fast, simple, and robust urine screening, particularly for cardiovascular drugs showing the usefulness of Orbitrap technology for drug testing., (Copyright © 2015 Elsevier B.V. All rights reserved.)