Etonitazene

The following information was compiled in November 2025 and is subject to change as new research is conducted and as new information becomes available:

Description: Etonitazene is a synthetic opioid characterized as a 2-benzylbenzimidazole (“nitazene analogue”). Etonitazene was originally synthesized in the 1950s as a potential analgesic; however, was never approved for clinical use.^1,2 Etonitazene has been reported in drug materials in Toronto and Thunder Bay, Canada.^3,4 Etonitazene was first identified by our laboratory in July 2025 and confirmed after acquiring standard reference material.

Sample Source: Toxicology UK (United Kingdom)

Sample Appearance: Blood specimen

Pharmacology: Etonitazene is a potent mu-opioid receptor agonist approximately 1000x more potent than morphine [K_i=38.4 nM, EC₅₀=0.588 nM, E_max (% hydromorphone)=254%).¹

Toxicology: Etonitazene has been detected in one toxicology case to date at the CFSRE.

Drug Materials: Etonitazene has not been detected in drug materials to date at the CFSRE.

Demographics / Geographics: The toxicology specimen originated from the United Kingdom. Etonitazene was identified alongside diazepam, cocaine, methadone, and heroin.

Legal Status: Etonitazene is a Schedule I drug in the United States.

Class:

Opioid

Appearance:

Blood specimen

Formula:

C22H28N4O3

MW:

396.5

[M+]:

396

[M+H]+:

397.2234

IUPAC:

2-[2-[(4-ethoxyphenyl)methyl]-5-nitro-benzimidazol-1-yl]-N,N-diethyl-ethanamine

Report Date:

November 12, 2025