Title: Etonitazene
CAS Registry Number: 911-65-9
CAS Name: 2-[(4-Ethoxyphenyl)methyl]-N,N-diethyl-5-nitro-1H-benzimidazole-1-ethanamine
Additional Names: 1-[(2-diethylamino)ethyl]-2-(p-ethoxybenzyl)-5-nitrobenzimidazole; 2-p-ethoxybenzyl-1-(2-diethylaminoethyl)-5-nitrobenzimidazole
Molecular Formula: C22H28N4O3
Molecular Weight: 396.48
Percent Composition: C 66.65%, H 7.12%, N 14.13%, O 12.11%
Literature References: Prepn: Hunger et al., Experientia 13, 400 (1957); Hoffmann et al., US 2935514 (1960 to Ciba). Crystal structure: C. Humblet et al., Acta Crystallogr. B34, 3828 (1978). Binds selectively to mu-opioid receptors: M. S. Moolten et al., Life Sci. 52, PL199 (1993).
Derivative Type: Hydrochloride
Molecular Formula: C22H28N4O3.HCl
Molecular Weight: 432.94
Percent Composition: C 61.03%, H 6.75%, N 12.94%, O 11.09%, Cl 8.19%
Properties: mp 162-164°.
Melting point: mp 162-164°
NOTE: This is a controlled substance (opiate): 21 CFR, 1308.11.
Therap-Cat: Analgesic (narcotic).
Keywords: Analgesic (Narcotic).
Etonogestrel Etoperidone Etorphine Etoxazole Etozolin

Systematic (IUPAC) name
Clinical data
Legal status Schedule I (CA) Schedule I (US)
CAS number 911-65-9 N
ATC code None
PubChem CID 13493
IUPHAR ligand 1624
DrugBank DB01462
ChemSpider 12908 YesY
UNII 9U3GT3353T YesY
Chemical data
Formula C22H28N4O3 
Mol. mass 396.48 g/mol
 N (what is this?)  (verify)

Etonitazene[1] is a potent analgesic drug shown to be approximately 1000–1500x the potency of morphine in animal models but only 60x in man.[2] It is one of several benzimidazole opioids, and is structurally related to clonitazene (where the p-ethoxybenzyl group is replaced by a p-chlorobenzyl group; however, clonitazene itself has only 3x the potency of morphine).

It has a strong dependency potential similar to that of morphine, and a strong tendency to produce respiratory depression, and is therefore not used in humans. It is however useful in addiction studies on animals. It is often used in studies requiring the animals to drink or ingest the opiate because it is not as bitter as the opiate salts, i.e., morphine sulfate.

It is the most potent benzimidazole opioid currently known.[3] Other analogues of considerable potency are as follows:

Nitazene general.png

Drug name R Analgesic Potency (Morphine = 1)
Etonitazene ethoxy 1000
Clonitazene chlorine 3
Nitazene hydrogen 2
methyl 10
ethyl 30
propyl 50
tert-butyl 2
methoxy 100
isopropoxy 500
butoxy 200
acetoxy 5
methylthio 50
ethylthio 30

Of these analogues, only etonitazene and clonitazene are explicitly listed as illegal drugs under UN convention and so are illegal throughout the world. The rest would only be illegal in countries such as the USA, Australia and New Zealand that have laws equivalent to the Federal Analog Act.

Etonitazene has proved very important in mapping out the opiate receptor and some experimental compounds in which phenolic groupings have been replaced with nitro groupings have proved more active than the parent compound.[citation needed]

Illicit production and sale of etonitazene has been limited. This compound was identified on the illegal drug market in Moscow in 1998, appeared to have been illicitly manufactured, and was primarily smoked as pre-laced cigarettes.[4] In another case a chemist at Morton Thiokol called Thomas K Highsmith [5] produced the compound and placed it in a nasal inhaler.