Hypersensitivity to opioids. Severe resp depression w/ hypoxia, cor pulmonale, cardiac arrhythmias, severe bronchial asthma, chronic bronchial asthma or other chronic obstructive airways disease, elevated blood CO
2 levels, paralytic ileus, acute abdomen, delayed gastric emptying, acute alcoholism, brain tumor, increased cerebrospinal or ICP, head injury, severe CNS depression, convulsive disorders, delirium tremens, hypercarbia, chronic constipation, concurrent MAOIs administration or w/in 2 wk of discontinuation of their use. Not recommended for pre-op use. Moderate to severe hepatic impairment. Severe renal impairment (CrCl <10 mL/min).