High Quality Content by WIKIPEDIA articles! Etonitazene is a potent analgesic drug shown to be approximately 1000–1500x the potency of morphine in animal models but only 60x morphine in man. 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.).