Intravenous morphine and oxycodone were given double blind in doses of 0.05 mg/kg after major abdominal surgery to 39 patients. The dosing interval was 5 min, until the patient did not want any further analgesics. Less oxycodone was needed than morphine, both to achieve the "first state of pain relief" (13.2 mg vs. 24.9 mg) and during the whole 2-h study period (21.8 mg vs. 34.2 mg). The "first state of pain relief" was achieved faster (28 min vs. 46 min) and lasted longer (39 min vs. 27 min) with oxycodone than morphine. Morphine caused more sedation and a greater decrease in the mean arterial blood pressure than oxycodone. In other respects the two opioids were comparable.

In order to determine the optimal pain treatment for patients with cancer involvement of the brachial or lumbar nerve plexuses, a prospective comparative study was carried out using peroral opioid therapy (SO), epidural opioid by a conventional tunnelled epidural catheter (CE) or an epidural catheter connected to an implanted injection port (Port). Pain relief, measured by a visual analog scale (VAS), was similar and adequate in every group already after the first 24 h. CNS side-effects were less frequent and the Karnofsky performance grades slightly superior in the epidural groups. Occlusion and catheter disconnection complicated the pain therapy of five epidural port patients. Epidural dislocation occurred three times in the conventional epidural group. One local infection in the CE group and two in the Port group were recorded. However, no signs of epidural infection were seen at autopsy. The results suggest that due to a lower incidence of side-effects, epidural catheter techniques are superior to peroral opioid in treating pain in these patients. However, complete pain relief was not achieved in all patients, suggesting neurogenic, non-nociceptive pain components. Both epidural techniques seem suitable for long-term pain therapy. Technical improvements are needed in the epidural catheter and the port. The long-term epidural catheter does not seem to cause any major changes in the histology of the dura mater or the connective tissue of the epidural space.

The analgesic profile and side-effects of buprenorphine 0.3 mg and morphine 10 mg intramuscularly were compared postoperatively in a double-blind, non-crossover, multiple-dose study. When the patient complained of moderate to severe postoperative pain after halothane-relaxant anesthesia for upper abdominal surgery, the first test dose of either drug was given. Subsequent similar doses of buprenorphine 0.3 mg or morphine 10 mg were given when required (maximum ten doses). The first dose of both drugs gave an equal decrease in pain intensity, suggesting a relative potency of 33:1 for both buprenorphine/morphine. A mean of 0.51 mg buprenorphine or 17 mg morphine had to be administered for satisfactory initial analgesia. Thereafter, the next analgesic dose was required a mean of 10.3 h after buprenorphine compared to 5.9 h after morphine (P less than 0.01). Significantly (P less than 0.01) fewer analgesic doses (mean 5.6) were needed in the buprenorphine group within the first 48 h postoperatively as compared to the morphine group (mean 7.3). A more pronounced mean decrease in the respiratory rate was observed after buprenorphine, but the mean minimum respiratory rates did not differ significantly from each other. Other effects of the two drugs on vital signs were similar. The incidence of other side-effects was fairly similar after both analgesics. The patients' subjective appraisal favoured buprenorphine.

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The analgesic dose-effect relationship of nefopam was compared in a double-blind randomised trial with that of oxycodone in immediate postoperative pain. Nefopam 15 mg or oxycodone 4 mg was given every 10 min i.v. (maximum six times) to patients in pain after upper abdominal surgery until their wound pain (scored 0-3) disappeared. The mean pain intensity (PI), initially 2.2 in both groups, descreased by approximately the same extent for up to two doses in both groups (to 1.5 after nefopam 30 mg and to 1.1 after oxycodone 8 mg). Thereafter PI was significantly less in the oxycodone group and diminished almost linearily to 0.1 after the sixth dose (24 mg). In the nefopam group, the PI score fell to 1.1 after the fourth dose (60 mg). This seemed to be the "ceiling" effect since additional doses up to 90 mg did not result in greater pain relief. In the oxycodone group, only two patients (12%) needed maximal dosage (6 x 4 mg), one of them requiring 32 mg of oxycodone. In the nefopam group, 12 patients (75%) needed further pain relief after the maximal dosage (6 x 15 mg). In these patients, oxycodone (maximally 16 mg) gave satisfactory analgesia. Drowsiness and a decrease in the respiratory rate were the principal side-effects of oxycodone, whereas tachycardia, restlessness, sweating and nausea were more frequent after nefopam.