Carfentanil or carfentanyl (also known as 4-carbomethoxyfentanyl) is an analog of the synthetic opioid analgesic fentanyl. It was found to be four orders of magnitude or 10,000 times more potent than morphine, making it one of the most potent known and the most potent commercially used opioids. Carfentanil was first synthesized in 1974 by a team of chemists at Janssen Pharmaceutica which included Paul Janssen. It is marketed under the trade name Wildnil as a general anaesthetic agent for large animals.