Fatal Intoxication with a mixture of para-methoxyamphetamine, N-ethylpentylone, and ketamine

Abstract

New psychoactive substances (NPS) have had a serious impact worldwide, and their determination in postmortem samples has been challenging. Here, we present a fatal case of poisoning involving the combined ingestion of para-methoxyamphetamine (PMA), N-ethylpentylone (NEP), and ketamine, and quantitative analysis of these drugs and para-hydroxyamphetamine (PHA), a primary metabolite of PMA. Case history: A man in his 20s was found dead in his room, wearing only underwear. Pink star-shaped tablets were found adjacent to the decedent. The tablets were submitted to a police forensic science laboratory and identified to contain PMA, NEP, and ketamine. An autopsy was performed in our laboratory, and samples of femoral vein blood and urine were collected for quantitative analysis. Quantitative analyses of PMA, NEP, ketamine, and PHA were performed using an ultra-high-performance liquid chromatograph coupled with a triple quadrupole tandem mass spectrometer (LCMS8030, Shimadzu). Blood samples were extracted using a Micro Volume QuEChERS kit (Shimadzu). Urine samples were prepared by diluting 100-fold with water prior to hydrolysis. Hydrolysis conditions were investigated using β-glucuronidase (Helix pomatia, type HP-2, ≥ 100,000 units/mL) or hydrochloric acid (HCl), as PHA was expected to form conjugates. The method was validated by assessing linearity, intra- and inter-day accuracy and precision, recovery, and matrix effect. Quantitative analyses revealed that the concentrations of PMA, NEP, and ketamine were 2.2 μg/mL, 0.21 μg/mL, and 0.22 μg/mL in femoral vein blood and 133 μg/mL, 9.5 μg/mL, and 13 μg/mL in urine, respectively. The concentration of PHA in urine was 24 μg/mL. PHA concentration was not affected by hydrolysis with β-glucuronidase, but was significantly increased with HCl. This result suggests that PHA is predominantly conjugated as sulfate, rather than glucuronide. The linearity (R2) of the calibration curves was > 0.99, and the accuracy and precision were < 15% for all the target drugs. Based on autopsy findings and toxicology results, the forensic pathologist concluded that the cause of death was intoxication by the simultaneous ingestion of PMA, NEP, and ketamine. Previous reports showed that the toxic blood levels for PMA and NEP ranged above 0.5 μg/mL and 0.1 μg/mL, respectively. The blood levels of PMA and NEP in the present case exceeded the toxic levels, which may have caused acute intoxication and led to death. Ketamine concentration was at the therapeutic level. As in this case, it is not unusual for several substances with different pharmacological effects, such as excitation, sedation, and hallucinations, to be detected simultaneously in a single NPS-related product. Products with multiple pharmacological actions may have unexpected effects on the human body. This report describes a fatal case of poisoning due to PMA, NEP, and ketamine. In addition, PHA, the primary active metabolite of PMA, was quantified in the postmortem samples. There have been no reports examining the hydrolysis conditions for PHA. These validated quantitative values would be helpful in interpreting the cases in which these drugs were ingested.