Indomethacin reduces raised intraluminal gallbladder pressure in acute cholecystitis

Indomethacin was recently shown to have a potent analgesic effect on biliary pain. The underlying mechanism is not fully clear, although reduction of increased gallbladder pressure by inhibition of prostaglandin synthesis had been suggested. For further clarification of this mechanism, the effect of intravenous indomethacin on the intraluminal gallbladder pressure was investigated in patients undergoing operation for acute cholecystitis. After laparotomy, gallbladder pressure was measured continuously during 25 min in 20 patients, 10 of whom received 100 mg indomethacin intravenously, while 10 were untreated controls. High intraluminal gallbladder pressure was found in all patients. Indomethacin reduced the average pressure by 11% in 20 min, whereas the corresponding pressure in the controls was constant. The results indicate that acute cholecystitis is associated with substantially raised intraluminal pressure, and that the analgesic action of indomethacin on biliary pain may be attributable to a local effect on gallbladder function, resulting in reduction of intraluminal pressure.