The effects of tramadol and morphine on immune responses and pain after surgery in cancer patients

There has been growing interest in determining the possible immune conseque nces of opioid administration fur the management of postoperative pain. We studied the effects of morphine and tramadol on pain and immune function du ring the postoperative period in 30 patients undergoing abdominal surgery f or uterine carcinoma. Phytohemoagglutinin-induced T lymphocyte proliferatio n and natural killer cell activity were evaluated immediately before and af ter surgery, and 2 h after the acute administration of either 10 mg of morp hine IM or 100 mg tramadol IM for pain. in all patients, phytohemagglutinin -induced lymphoproliferation was significantly depressed by surgical stress . However, in the morphine-treated group, proliferative values remained low er than basal levels for 2 h after treatment, whereas in tramadol-administe red patients proliferative values returned to basal levels. Natural killer cell activity was not significantly affected by surgery nor by morphine adm inistration, whereas tramadol significantly enhanced the activity of natura l killer cells. Both drugs produced a comparable reduction in postoperative pain. We conclude that, as previously observed in the experimental animal, tramadol and morphine, when administered in analgesic doses, induce differ ent immune effects.