Double-blind placebo-controlled comparison of dezocine and morphine for post-operative pain relief

Dezocine, a new mixed agonist-antagonist-type opioid analgesic, was compared in a double-blind trial with placebo and 10 mg of morphine in 190 patients with acute postoperative pain. The medications were given intramuscularly. Dezocine was administered at three dose levels (5, 10, and 15 mg). Pain relief scores, sedation, and side effects were recorded at 15, 30, 60, 120 and 240 min after injection. Significantly higher pain relief scores (p < 0.05) were reported for the groups receiving dezocine 10 and 15 mg than the placebo group at all observation times, except for dezocine 15 mg at four hours. Morphine produced significantly better pain relief than placebo only between the second and fourth hour after administration. Significantly better pain relief was obtained with dezocine (10 and 15 mg) than with morphine during the first hour. The mean four-hour cumulative pain relief scores (TOTPAR) were significantly (p < 0.05) higher than placebo for all active treatment groups. Side effects were few with no significant differences between the treatment groups. Seventy-nine per cent of the patients in the dezocine 15 mg group, and 73, 68, 58 and 50 per cent respectively, of the patients in the dezocine 10 mg, dezocine 5 mg, morphine 10 mg and placebo group had a satisfactory clinical response. Significantly (p < 0.05) more patients in the groups receiving dezocine 10 and 15 mg than in the placebo group had a satisfactory clinical response; the difference was not significant for the dezocine 5 mg and morphine 10 mg groups. We conclude that dezocine is a promising and safe analgesic, slightly more potent than morphine on a milligram per milligram basis for the relief of postoperative pain. Dezocine’s rapid onset of action after intramuscular injection presents an advantage over morphine.