Design and utility of open-access liquid chromatography tandem mass spectrometry in quantitative clinical toxicology and therapeutic drug monitoring

Population Pharmacokinetics of Caffeine in Infants with Hypoxic-Ischemic Encephalopathy: A Phase I, Dose-Escalating Trial

The mainstay of treatment for infants with hypoxic-ischemic encephalopathy (HIE) is cooling. Caffeine may be an important adjunct to cooling and provide neuroprotection via its anti-inflammatory and anti-oxidative properties. This study aimed to characterize caffeine pharmacokinetics in term infants with HIE receiving cooling. In this phase 1, dose-escalating study, enrolled infants received IV caffeine 20 mg/kg followed by up to two daily doses of 5 or 10 mg/kg. A population pharmacokinetic analysis was performed using NONMEM (v7.5). The effects of clinical covariates, including cooling, on pharmacokinetic parameters were evaluated. Dosing simulations were performed to evaluate the percentage of plasma exposures in the reference range (15-25 mg/L). Seventeen infants were included in model development. A one-compartment model best fit the data. Population clearance was 0.445 L/h/70 kg and volume of distribution was 87.1 L/70 kg. Current dosing regimens (20 mg/kg followed by 5 mg/kg) resulted in 89.5% of infants having at least one simulated exposure below the reference range across the dosing interval. Dosing regimens of 30 mg/kg followed by 5 or 10 mg/kg were predicted to result in more than half of infants achieving simulated exposures in the reference range, with ≤20% of infants having simulated exposures in the toxic range (>46 mg/L). Term infants with HIE had similar weight-normalized clearance but higher weight-normalized volume of distribution compared to prior studies in preterm infants without HIE or cooling. While exposure targets for neuroprotection in HIE are unknown, this phase 1 study suggests alternate dosing strategies should be considered in future studies.

Analysis of 14 drugs in dried blood microsamples in a single workflow using whole blood and serum calibrators

Aim: Multiplexed, high-throughput analysis facilitates therapeutic drug monitoring. 14 drugs with various physico-chemical properties were quantitated in dried blood microsamples. Methods: Analytes were extracted employing eight solvent compositions and seven extraction methods. The applicability of liquid serum, dried serum and dried whole blood calibrators was investigated. Results: High recoveries were attained. Calibration using dried serum yielded lowest total error. Reducing sample hematocrit caused outstanding elevations in recovery of analytes with high polarity or affinity to erythrocytes. 9-day analyte stability was demonstrated. Conclusion: Based on the analysis of spiked samples, multiplexed testing of drugs in dried blood microsamples seems feasible, but with analyte-dependent method performance. Dried serum calibration allows the adaptation of serum-based workflows. Further evaluation using real-life specimens is needed.

MASS SPECTROMETRY ANALYSIS OF DRUGS OF ABUSE: CHALLENGES AND EMERGING STRATEGIES

Mass spectrometry has been the "gold standard" for drugs of abuse (DoA) analysis for many decades because of the selectivity and sensitivity it affords. Recent progress in all aspects of mass spectrometry has seen significant developments in the field of DoA analysis. Mass spectrometry is particularly well suited to address the rapidly proliferating number of very high potency, novel psychoactive substances that are causing an alarming number of fatalities worldwide. This review surveys advancements in the areas of sample preparation, gas and liquid chromatography-mass spectrometry, as well as the rapidly emerging field of ambient ionization mass spectrometry. We have predominantly targeted literature progress over the past ten years and present our outlook for the future. © 2020 Periodicals, Inc. Mass Spec Rev.

After another decade: LC-MS/MS became routine in clinical diagnostics

Tandem mass spectrometry - especially in combination with liquid chromatography (LC-MS/MS) - is applied in a multitude of important diagnostic niches of laboratory medicine. It is unquestioned in its routine use and is often unreplaceable by alternative technologies. This overview illustrates the development in the past decade (2009-2019) and intends to provide insight into the current standing and future directions of the field. The instrumentation matured significantly, the applications are well understood, and the in vitro diagnostics (IVD) industry is shaping the market by providing assay kits, certified instruments, and the first laboratory automated LC-MS/MS instruments as an analytical core. In many settings the application of LC-MS/MS is still burdensome with locally lab developed test (LDT) designs relying on highly specialized staff. The current routine applications cover a wide range of analytes in therapeutic drug monitoring, endocrinology including newborn screening, and toxicology. The tasks that remain to be mastered are, for example, the quantification of proteins by means of LC-MS/MS and the transition from targeted to untargeted omics approaches relying on pattern recognition/pattern discrimination as a key technology for the establishment of diagnostic decisions.

Online Extraction Coupled to Liquid Chromatography Analysis (OLE-LC): Eliminating Traditional Sample Preparation Steps in the Investigation of Solid Complex Matrices

Current methods employed for the analysis of the chemical composition of solid matrices (such as plant, animal, or human tissues; soil; etc.) often require many sample treatment steps, including an extraction step with exclusively dedicated solvents. This work describes an optimized analytical setup in which the extraction of a solid sample is directly coupled to its analysis by high-performance liquid chromatography. This approach avoids (i) the use of pumps and valves other than those comprising the HPLC instrument, (ii) the use of solvents other than those of the mobile phase, and (iii) the need to stop the mobile phase flow at any time during the full analytical procedure. The compatibility of this approach with the direct analysis of fresh tissues (leaves, stems, and seeds of four plant species with dissimilar chemical compositions) was successfully demonstrated, leading to the elimination of sample preparation steps such as drying, grinding, concentration, dilution, and filtration, among others. This work describes a new, simple, and efficient green approach to minimize or eliminate sample treatment procedures. It could be easily applied for quality control of plant materials and their derived products through chromatographic fingerprints and for untargeted metabolomic investigations of solid matrices, among other applications.