Postmortem distribution of mepirapim and acetyl fentanyl in biological fluid and solid tissue specimens\xa0measured by the standard addition method

Akira Mochizuki,Hideki Shojo,Hiroko Nakazawa,Kenichi Takekawa,Noboru Adachi

doi:10.1007/s11419-018-0431-z

Abstract

PurposeMepirapim is a new synthetic cannabinoid. We previously reported that the concentrations of unchanged mepirapim in whole blood and urine were much higher than those of other synthetic cannabinoids. To determine the postmortem distribution of mepirapim and acetyl fentanyl in the deceased individual, we established a standard addition method for detailed analysis by liquid chromatography–mass spectrometry (LC–MS) for quantification of these drugs.MethodsThe LC–MS method was fully validated for linearity, extraction recovery, matrix effect and repeatability.ResultsGood linearities, extraction recoveries, matrix effects and repeatabilities were shown for both target compounds in all specimens. The concentrations of mepirapim and acetyl fentanyl in three body fluid specimens and 12 solid tissue specimens were measured. For mepirapim, the highest concentrations were found in the liver and kidney, and the concentrations in the blood and urine specimens were one order of magnitude lower than the high concentrations in the solid tissues except the psoas major muscle. For acetyl fentanyl, the highest concentrations were found in the myocardium, spleen and kidney, and the concentrations in the body fluid specimens were also one order of magnitude lower than the highest concentrations in the solid tissues. There were concentration differences of mepirapim and acetyl fentanyl among the regions of the brain.ConclusionsThe concentration of unchanged mepirapim in urine was much higher than those of other synthetic cannabinoids; the higher dosage, urinary excretion, metabolisms and/or pharmacokinetics of mepirapim may be quite different from those of other synthetic cannabinoids.

Highlights

Illicit psychoactive substances have become a serious threat worldwide as designer drugs of abuse [1,2,3]
To confirm the linearity of the calibration curve for mepirapim and acetyl fentanyl, the standard addition calibration curves were constructed in suitable concentration ranges as shown in Table 1 for the body fluid and solid tissue specimens by using six plot points at different concentrations each (n = 5 each)
We quantified mepirapim and acetyl fentanyl in body fluid and solid tissue specimens taken from the deceased individual by liquid chromatography–mass spectrometry (LC–MS) using the standard addition method

Summary

Introduction

Illicit psychoactive substances (e.g., synthetic cannabinoids, cathinone derivatives and synthetic opioids) have become a serious threat worldwide as designer drugs of abuse [1,2,3]. We have quantified both mepirapim and acetyl fentanyl in as many as 15 specimens. To our knowledge, this is the most detailed study to date for the distribution of acetyl fentanyl, and is the first demonstration of distribution of mepirapim in an authentic fatal poisoning case. This is the most detailed study to date for the distribution of acetyl fentanyl, and is the first demonstration of distribution of mepirapim in an authentic fatal poisoning case Such detailed investigation of postmortem distribution is very useful for evaluating the cause(s) of death. We have used the standard addition method for analysis by liquid chromatography–mass spectrometry (LC–MS), which can overcome the different matrix effects and recovery rates in different specimens, and does not need blank human matrices for validation experiments

Methods

Results

Discussion

Conclusion