Interpretation of analytical results of the substances encountered in the chemsex related cases-focus on instability and post-mortem redistribution problems through two cases

Analytical toxicologists are currently regularly confronted with analyses as part of the practice of chemsex in clinical or forensic toxicology. Given the nature of the substances that can be found in these chemsex files, it is sometimes necessary to consider pre -analytical elements (in cadaver and in vitro instability and post-mortem redistribution) to interpret blood concentrations in relation to the question asked (possible toxic effects in relation to a clinical picture or the occurrence of death). Through two case studies, this manuscript presents these difficulties and the elements available in the literature concerning GHB, new psychoactive substances, foremost among which are synthetic cathinones, cocaine, methamphetamine and sildenafil. There are phenomena of instability and/or post-mortem redistribution for substances very regularly found in these files (in particular, GHB, synthetic cathinones and cocaine), which should be known to analytical toxicologists (and forensic scientists) and taken into consideration. In practice, however, they do not necessarily influence the general toxicological interpretation of dossiers. (c) 2023 Societe Francaise de Toxicologie Analytique. Published by Elsevier Masson SAS. All rights reserved.