Full agonist opiates in acute pancreatitis: are they really contraindicted?
There are some pieces of wisdom passed down through generations of veterinary teaching which acquire mythical status: their origins lost in the mists of time.
Amongst these is the ‘rule’ that full agonist opiates are contraindicated in acute pancreatitis because of the potential for bilary spasm in the face of potential obstruction due to pancreatic swelling and/or fibrosis.
I’ve heard this discussed at conferences and heard the contention voiced that this rule is not actually based on firm evidence. Anyway, this is the paper:
J Med. 1979;10(4):225-38.
Comparative gastrointestinal and biliary tract effects of morphine and butorphanol (Stadol).
Roebel LE, Cavanagh RL, Buyniski JP.
https://www.ncbi.nlm.nih.gov/pubmed/43349
Abstract:
Butorphanol, levo-N-cyclobutylmethyl-3,14 beta-dihydroxy-morphinan, is a new agonist-antagonist type analgetic agent which is 4 to 8 times more potent than morphine in experimental animals and man. Butorphanol and morphine were evaluated in mice and dogs for their gastrointestinal and biliary tract smooth muscle effects. Morphine decreased the propulsion of a charcoal meal through the gastrointestinal tract of the mouse in a dose related manner with the maximal inhibition obtainable being 90%. Butorphanol produced a maximal inhibition of motility of only 40% with very high doses producing less of an inhibitory effect than lower doses. In dogs, morphine caused a dose-dependent increase in duodenal smooth muscle activity and a dose-dependent decrease in bile duct flow. A clinically effective i.v. dose of morphine (0.1 mg/kg) produced a statistically significant spasmogenic effect on dog biliary tract and gastrointestinal smooth muscle, while a clinically effective equianalgetic i.v. dose of butorphanol (0.025 mg/kg i.v.) had little or not effect on the biliary or gastrointestinal systems. These findings indicate that at equianalgetic doses, butorphanol should produce less constipation and less biliary tract and gastrointestinal smooth muscle spasm than morphine.
