Isotonitazene is a benzimidazole derived opioid analgesic drug related to etonitazene. It has only around half the potency of etonitazene in animal studies, but it is likely even less potent in humans as was seen with etonitazene (1000 times as potent as morphine in animal models yet only 60 times as potent in humans). Isotonitazene been sold as a designer drug, and can be obtained from an online vendor. Side effects of benzimidazole derived opioids are likely to be similar to those of fentanyl, which include itching, nausea and potentially serious respiratory depression, which can be life-threatening.