Nalbuphine, acetaminophen, and their combination in postoperative pain.

In a double-blind study with the use of subjective reports of patients as indices of analgesia, we compared the analgesic effect of oral nalbuphine and acetaminophen and determined the contribution of each to the efficacy of their combination. In this parallel 2 X 2 factorial study, 129 inpatients after surgery were randomly assigned to treatment with a single oral dose of nalbuphine hydrochloride (30 mg), acetaminophen (650 mg), the combination of nalbuphine (30 mg) and acetaminophen (650 mg), or placebo. In the factorial analysis, both the nalbuphine and acetaminophen effects were significant for virtually every measure of total and peak analgesia, whereas the interaction contrast was not significant for any measure of analgesic effect. This indicates that the analgesic effect of the combination represents the additive effect of its constituents and is consistent with the results of studies of combinations of codeine and other opioids with aspirin or acetaminophen. There were few adverse effects other than sedation, which occurred twice as frequently in patients treated with nalbuphine as in those receiving acetaminophen or placebo. Our data suggest that this combination should prove at least as effective as any currently marketed narcotic-containing combination. Since nalbuphine has less dependence liability than narcotics and exhibits a ceiling on respiratory depression, its combination with acetaminophen should also be safer than comparable narcotic combinations.