In Vitro Metabolite Identification Studies for the New Psychoactive Substances Furanylfentanyl, TFMPP, and 5-MeO-DALT in Human Liver Microsomes

Aims: Understand the metabolic behavior of new psychoactive substances, furanyl fentanyl, TFMPP, and 5-MeO-DALT. Background: New psychoactive substances (NPS) are associated with several health and social harms on both the individual and societal levels. Many are not regulated and have become increasingly popular among drug users worldwide. The lack of clinical studies on the effects and toxicity of these drugs has made the interpretation of their toxicological symptoms difficult. Objective: Perform an in vitro metabolism study of new psychoactive substances furanyl fentanyl, TFMPP, and 5-MeO-DALT, revealing their possible metabolites and metabolic pathways in the human liver microsome. Methods: A regular human liver microsomal system was used to investigate the potential biotransformation of furanyl fentanyl, TFMPP, and 5-MeO-DALT in vitro, and high-resolution mass spectrometry (LC-Q/TOF-MS) was used to perform metabolite detection and identification. Results: The three components were substantially metabolized in 4 hours with varied metabolic pathways, and most of the metabolites were generated through phase I metabolic reactions. Furanyl fentanyl underwent the metabolic pathways of epoxidation and hydration, furanyl ring-opening and oxidation, hydroxylation, hydrolysis of the amide group, and N-dealkylation; TFMPP underwent the metabolic pathways of hydroxylation, and the successive piperazidine ring scission; while 5-MeO-DALT underwent the metabolic pathways of O-demethylation and glucuronidation, dihydroxylation, hydroxylation, oxidation, O-demethylation, N-dealkylation and methylation and N-dealkylation. Conclusion: Our data would contribute to a better understanding of furanyl fentanyl, TFMPP, and 5- MeO-DALT in their in vitro metabolism study, which was beneficial to predicting their metabolic behavior in vivo, and promoting their drug monitoring in both clinically used and socially/illegally abused.