Etoacetazene
Etoacetazene is a benzimidazole derivative with opioid effects, first developed in the 1950s as part of the research that led to better-known compounds such as etonitazene. It is an analogue of etonitazene where the 5-nitro group has been replaced by an acetyl group. It is described as having "reduced but still significant" potency compared to etonitazene itself. This compound was also tested as part of a series of cannabinoid receptor 2 agonists, and was found to be active though with fairly low potency of 960 nM at CB2, and negligible activity at CB1.