Lewis Couchman

Aim: The aim of this study was to present summary data from a serum clozapine proficiency testing scheme. Methods: Monthly returns submitted to the LGC Standards clozapine and norclozapine proficiency testing scheme between 2012 and 2024 were analyzed. Results: A total of 191 participating laboratories participated, of which 164 reported norclozapine results. From 2013 to 2024, the number of returns per distribution was 85. The proportion of laboratories using liquid chromatography–mass spectrometry increased over time and reached 74% in 2024, while the use of high-performance liquid chromatography decreased. Thirteen distributions contained neither analyte; however, 76 returns (6.8%) reported detectable clozapine concentrations (median 10.4, range 0.01–518.73 mcg L ⁻¹ ). In 22 distributions, clozapine concentrations >10 mcg L ⁻¹ (median 151.63, range 30.3–2175.25 mcg L ⁻¹ ) were detected but reported as “0” or below the lower limit of quantification. Comparable findings were observed for norclozapine. No temporal differences in quantitative performance, assessed using z-scores, were observed between analytical methods. Median clozapine z-scores were further from zero when clozapine alone was measured than when both clozapine and norclozapine were measured. Conclusions: Increased use of liquid chromatography–mass spectrometry was not associated with improved analytical performance for clozapine or norclozapine. Method validation should include assessment of potential interference from metabolites and coadministered drugs. Unexpected results require repeat analysis or repeat sampling when clinically feasible.

N, N-Dimethyltryptamine (DMT) is a hallucinogen found in the South American Psychotria viridis plant and is the major psychoactive ingredient in the brew ayahuasca. In this report, we performed a review of the surrounding literature and detail two deaths which recently occurred in the UK following DMT use. A literature search of both academic (PubMed, GoogleScholar) and media (using Google search engine) publications was performed to identify previously reported fatalities following DMT use. The National Programme on Substance Use Mortality (NPSUM) was also searched for deaths which have occurred in the UK following DMT use. Literature search—There have been three previous reports of fatalities following DMT use, all deemed accidental in nature, with DMT consumption taking place as part of an ayahuasca ceremony in two of these cases. NPSUM cases—Two cases were identified (Case Report 1 [CR1] & Case Report 2 [CR2]), neither of which occurred in the context of an ayahuasca ceremony. DMT was detected and quantified in femoral blood in both cases (CR1 0.23 mg/l; CR2 0.24 mg/l). There was evidence of polydrug use in both cases (CR1 n = 6; CR2 n = 9), which in each case included additional compounds which can increase serotonergic drive (CR1 cocaine, amphetamine; CR2 venlafaxine, mirtazapine). There have been two recent deaths following DMT use in the UK, both in the context of polydrug use which may have caused death due to excessive serotonergic innervation leading to serotonin syndrome. Polydrug use is increasingly common in the UK, and users of unregulated drugs should caution their use in combination with other unregulated drugs and also any prescribed medications.

In recent years the use of 2-benzylbenzimidazole opioids (‘nitazenes’) has increased with them becoming one of the most prominent synthetic opioid subclasses of novel psychoactive substances. With the increased prevalence there is also a concern of the dangers to public health with the use of nitazenes due to their high potency especially with polypharmacy. To aid in the detection of such compounds it is important that forensic toxicology laboratories maintain up-to-date compound libraries for drug screening methods and that sensitive analytical instrumentation is available to detect the low blood/plasma concentrations of more potent drugs. This includes not only the compounds themselves but also potential metabolites and/or degradation products. Metonitazene is a ‘nitro-nitazene’ with a nitro group at position 5 of the benzimidazole ring. As a nitro-nitazene there is a potential for bacterial degradation of metonitazene to 5-aminometonitazene, as occurs with nitro-benzodiazepines. In this study we provide evidence from a post-mortem case of degradation of metonitazene in unpreserved post-mortem blood using LC-QQQ-MS, and putative identification of the degradation/ metabolic products 5-aminometonitazene and 5-acetamidometonitazene by LC-QTOF-MS. The results from LC-QQQ-MS analysis indicated that there did not appear to be such degradation in preserved (fluoride/oxalate) blood. These results suggest that nitro-nitazenes may be subject to similar in vitro stability/degradation issues as nitro-benzodiazepines. These breakdown products should be added to instrument libraries to aid in the detection of the use of nitro-nitazenes, and nitro-nitazenes should be quantified in preserved blood samples where available.

The surging number of people who abuse drugs has a great impact on healthcare and law enforcement systems. Amnesty bin drug analysis helps monitor the "street drug market" and tailor the harm reduction advice. Therefore, rapid and accurate drug analysis methods are crucial for on-site work. An analytical method for the rapid identification of five commonly detected drugs ((3,4-methylenedioxymethamphetamine (MDMA), cocaine, ketamine, 4-bromo-2,5-dimethoxyphenethylamine, and chloromethcathinone)) at various summer festivals in the U.K. was developed and validated employing a single quadrupole mass spectrometer combined with an atmospheric pressure solids analysis probe (ASAP-MS). The results were confirmed on a benchtop gas chromatography-mass spectrometry instrument and included all samples that challenged the conventional spectroscopic techniques routinely employed on-site. Although the selectivity/specificity step of the validation assessment of the MS system proved a challenge, it still produced 93% (N = 279) and 92.5% (N = 87) correct results when tested on- and off-site, respectively. A few "partly correct" results showed some discrepancies between the results, with the MS-only unit missing some low intensity active ingredients (N-ethylpentylone, MDMA) and cutting agents (caffeine, paracetamol, and benzocaine) or detecting some when not present. The incorrect results were mainly based on library coverage. The study proved that the ASAP-MS instrument can successfully complement the spectroscopic techniques used for qualitative drug analysis on- and off-site. Although the validation testing highlighted some areas for improvement concerning selectivity/specificity for structurally similar compounds, this method has the potential to be used in trend monitoring and harm reduction.

Quantitation of proteins using liquid chromatography-tandem mass spectrometry (LC-MS/MS) is complex, with a multiplicity of options ranging from label-free techniques to chemically and metabolically labeling proteins. Increasingly, for clinically relevant analyses, stable isotope-labeled (SIL) internal standards (ISs) represent the "gold standard" for quantitation due to their similar physiochemical properties to the analyte, wide availability, and ability to multiplex to several peptides. However, the purchase of SIL-ISs is a resource-intensive step in terms of cost and time, particularly for screening putative biomarker panels of hundreds of proteins. We demonstrate an alternative strategy utilizing nonhuman sera as the IS for quantitation of multiple human proteins. We demonstrate the effectiveness of this strategy using two high abundance clinically relevant analytes, vitamin D binding protein [Gc globulin] (DBP) and albumin (ALB). We extend this to three putative risk markers for cardiovascular disease: plasma protease C1 inhibitor (SERPING1), annexin A1 (ANXA1), and protein kinase, DNA-activated catalytic subunit (PRKDC). The results show highly specific, reproducible, and linear measurement of the proteins of interest with comparable precision and accuracy to the gold standard SIL-IS technique. This approach may not be applicable to every protein, but for many proteins it can offer a cost-effective solution to LC-MS/MS protein quantitation.

Globally, the number of drug users and the proportion of the drug using population has increased from 210 million in 2009 to 269 million in 2019. Several studies suggest that music festival attendees are more likely to abuse illicit substances and have a high‐risk profile. Consequently, it is crucial to develop robust field drug analysis methods that facilitate harm reduction and drug monitoring. The work presented in this report aimed at developing and validating qualitative analytical methods for 3,4‐methylenedioxymethamphetamine, 4‐bromo‐2,5‐dimethoxyphenethylamine (2C‐B), ketamine and N‐ethylpentylone on two portable gas chromatography–mass spectrometry (GC–MS) systems: Griffin G510 (Teledyne FLIR, West Lafayette, IN) and Torion T‐9 (PerkinElmer, Shelton, CT). The diagnostic ability of the mobile GC–MS units was assessed on 200 samples in total, seized at two large summer music festivals in the United Kingdom. The method validation process included selectivity/specificity, limit of identification, carry‐over, ruggedness/robustness, and inter‐ and intra‐day precision (repeatability and reproducibility). The Griffin G510 demonstrated a limit of identification from 1 mg/mL for 2C‐B to 0.063 mg/mL for ketamine and good ruggedness and precision results. The precision for 2C‐B using the Torion T‐9 was poorer than for the Griffin G510, but equivalent for the other compounds tested. Correct identifications (versus benchtop GC–MS) for the two festivals were 85%–86% and 74%–83% for the Griffin G510 and the Torion T‐9, respectively. The two portable instruments were able to adequately cover current on‐site drug‐testing analytical gaps and proved to be a powerful addition to the on‐site drug analysis techniques.

This study predicted dapaconazole clinical drug–drug interactions (DDIs) over the main Cytochrome P450 (CYP) isoenzymes using static (in vitro to in vivo extrapolation equation, IVIVE) and dynamic (PBPK model) approaches. The in vitro inhibition of main CYP450 isoenzymes by dapaconazole in a human liver microsome incubation medium was evaluated. A dapaconazole PBPK model (Simcyp version 20) in dogs was developed and qualified using observed data and was scaled up for humans. Static and dynamic models to predict DDIs following current FDA guidelines were applied. The in vitro dapaconazole inhibition was observed for all isoforms investigated, including CYP1A2 (IC₅₀ of 3.68 µM), CYP2A6 (20.7 µM), 2C8 (104.1 µM), 2C9 (0.22 µM), 2C19 (0.05 µM), 2D6 (0.87 µM), and 3A4 (0.008–0.03 µM). The dynamic (PBPK) and static DDI mechanistic model-based analyses suggest that dapaconazole is a weak inhibitor (AUCR > 1.25 and 2 and <5) of CYP2C8 and CYP2D6, and a strong inhibitor (AUCR ≥ 5) of CYP2C19 and CYP3A, considering a clinical scenario. The results presented may be a useful guide for future in vivo and clinical dapaconazole studies.