Protonitazepyne (N-pyrrolidino protonitazene) is a benzimidazole derivative with opioid effects, which has been sold as a designer drug over the internet, first being mentioned in mid 2022 and definitively identified in drug seizures in Canada in early 2023 and Ireland in late 2023.[1] It is an analogue of etonitazene where the ethoxy group has been extended to propoxy, and the N,N-diethyl substitution has been cyclised into a pyrrolidine ring. While formal studies into its pharmacology have yet to be carried out, it is believed to be slightly less potent than the ethoxy analogue etonitazepyne but still a potent opioid.[2] [3]