Opioid and nonopioid analgesic drug effects on colon contractions in monkeys

Opioid drugs administered postoperatively for pain relief cause increased frequency of nonpropulsive phasic contractions but decreased to absent propulsive migrating contractions in the colon, thus importantly influencing the duration of postoperative ileus. Ketorolac is thought to permit earlier return of bowel function postoperatively compared to morphine. Four monkeys had sets of three strain gauge force transducers implanted on the right and left colon at laparotomy. After recovery, animals were fasted overnight and had colon contractions recorded. After a 1-hr baseline period, 200 micrograms/kg morphine sulfate or 1 mg/kg ketorolac tromethamine was injected intramuscularly and recording continued. Each animal received four injections of each drug. Records were analyzed visually for frequency of phasic on migrating contractions. There was no difference in the frequency of phasic or migrating contractions after injection of ketorolac. Morphine, as expected, increased the frequency of phasic and decreased the frequency of migrating contractions in the colon. Ketorolac does not affect the frequency of colon contractions.