Opiates in the treatment of acute pancreatitis: bile duct spasm myth or reality?
The idea floats around that pure agonist opioids such as morphine and methadone are potentially contraindicated in situations where extrahepatic biliary obstruction is a possibility -such as acute severe pancreatitis. In most texts this remains unsubstantiated and I have certainly heard it debunked as anecdote in presentations.
However, this appears to be the origin:
Personally, I have moved to using buprenorphine backed up with lidocaine and ketamine as a CRI in severe cases.