Identification and quantification of diphenidine in hair by LC-MS/MS after single administration

Hair Analysis of Methoxphenidine in a Forensic Chemsex Case

Methoxphenidine (MXP, 2-MeO-diphenidine) is a dissociative anaesthetic drug of the diarylethylamine type, recently introduced for recreational purposes through the online-based sale of new psychoactive substances (NPS). The concentration of MXP in hair has never been reported, either in cases of chemsex use or in fatal cases. A 55-year-old man was found dead at home the morning after a chemsex party. Toxicological analyses indicated high concentrations of MXP in femoral blood (606 µg/L), cardiac blood (254 µg/L), and hair (13 ng/mg). We also identified 3-MMC in femoral blood (traces) and urine (238 µg/L). The concentrations of all other drugs were consistent with living subjects. This case highlights the risk of methoxphenidine poisoning in the context of chemsex and emphasises the importance of including NPS in post-mortem toxicology examinations.