Effects of butorphanol, fentanyl and morphine on the intrabiliary pressure of guinea pigs.

Alleged injury to the liver by halogenated hydrocarbon anesthetic agents has led to greater use of balanced anesthesia with analgesics, tranquilizers and nitrous oxide and oxygen. Reports of high intrabiliary pressures and bizarre cholangiograms for patients under such anesthesia led us to investigate the specific effects on intrabiliary pressure of morphine sulfate, fentanyl and butorphanol tartrate, each at two different dosage levels. After control measurements were taken, all of the guinea pigs, an animal with a biliary tract much like that of man, were injected with a different drug, dosage level or with 0.9 per cent saline solution, and changes in intrabiliary pressure were recorded every five minutes. Both high and low dosages of morphine and fentanyl produced marked and statistically significant increases in the intrabiliary pressure. In contrast, equianalgesic dosage of butorphanol produced little or no increase. Since two of these drugs can elevate intrabiliary pressure significantly above pretreatment values, it is recommended that dilations of the biliary tract occurring during operative cholangiograms be interpreted with caution.