Carfentanil (also known as Carfentanyl, 4-carbomethoxyfentanyl R33799) is an analog of the synthetic opioid analgesic Fentanyl. Carfentanil was first synthesized in 1974 by a team of chemists at Janssen Pharmaceutica which included Paul Janssen. Google Us Moreover, Carfentanyl is comprised of a carboxymethyl group in the fourth position of the pip