Metabolism and toxicological analyses of hallucinogenic tryptamine analogues being abused in Japan

Hallucinogenic tryptamine analogues, an important class of drugs of abuse, can be naturally occurring or chemically synthesized compounds. In Japan, psilocin and psilocybin (ingredients of magic mushrooms) and 5-methoxy-N,N-diisopropyltryptamine (5-MeO-DIPT; a synthetic tryptamine) seem to be particularly problematic due to their extensive abuse. This review is focused on human metabolism and forensic toxicological analyses of the above three tryptamine analogues. In humans, psilocybin is rapidly dephosphorylated to form psilocin, and most of the psilocin is eventually conjugated to form its glucuronide. On the other hand, 5-MeO-DIPT is mainly metabolized via O-demethylation, 6-hydroxylation, and N-deisopropylation, partly followed by conjugation to form their sulfates and glucuronides. Suitable hydrolysis should be, therefore, applied for sensitive and effective analysis of the metabolites. In analyzing psilocin and psilocybin by gas chromatography-mass spectrometry (GC-MS), derivatization is necessary for their discriminative identification. Although 5-MeO-DIPT and its three major metabolites can be analyzed by GC-MS without any derivatization, trimethylsilyl derivatization provides improvement of their peak shapes and intensities. In contrast to GC-MS, liquid chromatography-mass spectrometry and liquid chromatography-tandem mass spectrometry allow us not only to discriminate psilocin and psilocybin without derivatization, but also to directly analyze their conjugated metabolites.