This NPS metabolism monograph highlights N-propionitrile chlorphine (also known as cyclorphine or cychlorphine), a novel synthetic opioid (NSO) first identified by the CFSRE in 2024. Structurally related to brorphine, a potent μ-opioid receptor agonist and DEA Schedule I controlled substance, this analog reflects the growing global prevalence of modified synthetic opioids in the emerging "orphine" class. Using pooled human liver microsomes in vitro and LC-MS/MS, the monograph identifies presumptive phase I metabolites to support forensic toxicologists in detecting emerging NSOs.

To cite this monograph: Bassman, J.R., Layle, N.K., Goodwin, S.K., et al. N-Propionitrile Chlorphine. Cayman NPS Metabolism Monograph Issue 4 (2025).