Meptazinol for postoperative pain relief in man. Comparison of extradural and i.m. administration.

The analgesic and cardiorespiratory effects of meptazinol 90 mg, given by the extradural or the i.m. route, were studied in 32 postoperative patients. Plasma meptazinol concentrations were measured in five patients in each treatment group. Evaluation using a linear analogue scale indicated that there were significant differences between the groups in the onset, quality and duration of pain relief, with the extradural route being superior to the i.m. route in each instance. The difference in quality of pain relief was not related to the resultant plasma meptazinol concentrations, which were similar in the two groups. Ventilatory rate was decreased equally in both groups in parallel with pain relief, but no incidence of overt respiratory depression was noted. Meptazinol produced no meaningful changes in measured cardiovascular variables, and side effects were minimal in both groups.