Intravenous doses of
butorphanol tartrate (0.5 mg, 1.0 mg and 2.0 mg) and
meperidine hydrochloride (20 mg and 40 mg) were compared under controlled conditions employing a double blind study design. Informed consent was obtained from all post-operative patients suffering from moderate to severe
pain who participated in this study. Approximately 25 patients were included in each group. The data from 125 patients were subjected to statistical analysis. The results indicated that
butorphanol is approximately 40 to 50 times more potent than
meperidine. In addition, at most of the time intervals, there were no statistically significant differences between the responses to
butorphanol 0.5 mg and 1 mg and
meperidine 20 mg and 40 mg; but the response to
butorphanol 2 mg was significantly (p less than 0.05) better than the low dose of each agent. The low doses of
butorphanol (0.5 mg) and
meperidine (20 mg) appear to have an effective duration of action of less than two hours. The larger doses (
butorphanol 1.0 mg and 2.0 mg and
meperidine 40 mg) appeared to produce a two- to four-hour duration of action. The largest
butorphanol dose (2.0 mg) appeared to produce the longest duration of action. A comparison of the test groups with respect to the incidence and type of side effects showed that
butorphanol 2.0 mg produced a greater incidence of drowsiness (39 per cent). The overall incidence of drowsiness for patients receiving either the 0.5 mg or 1.0 mg dose of
butorphanol was 12 per cent, as compared with an 8 per cent overall incidence in the
meperidine group. The incidence of other side effects was relatively low in all test groups. No significant differences were noted among the groups with regard to the onset (usually less than or equal to 30 minutes post-
therapy) or the duration (usually less than or equal to 2 hours) of side effects.
Butorphanol appears to be a safe and effective
analgesic for the relief of moderate to severe
post-operative pain.