Carfentanil

Carfentanil is an ultra-potent synthetic opioid and a structural analogue of fentanyl. It is one of the most powerful opioids known, estimated to be approximately 10,000 times more potent than morphine and 20 to 100 times more potent than fentanyl. It is strictly intended for veterinary use as a tranquilizing agent for very large animals like elephants and rhinos, and is not approved for human use due to its extreme potency.