[Postoperative pain therapy with piritramide and metamizole. A randomized study in 120 patients with intravenous on-demand analgesia after abdominal surgery.].

In this randomized study, the efficacy of i.v. patient-controlled analgesia (PCA) was determined for the opioid piritramide (a pure mu-receptor agonist) and the antipyretic analgesic metamizole (Dipyrone) in three groups of patients following abdominal surgery. The doses of piritramide were 1.5 mg (40 patients) and 3 mg (40 patients) on demand. In addition, we studied the effect of 71 mg metamizole in combination with on-demand boluses of 1.5 mg piritramide in 40 patients. During PCA we estimated the degree of analgesia (verbal gain rating scale, visual analog scale) and monitored the ventilation, vigilance, and typical drug side effects over a period of 24 h. The individual demand for analgesic drugs varied markedly. The mean consumption of piritramide during the study was 46.5 mg in the group with 1.5 mg per bolus and 68.6 mg in the group with 3.0 mg. The resulting pain relief was satisfactory in both groups. The combination of piritramide 1.5 mg and metamizole 71 mg per bolus resulted in a reduction of mean Piritramide-consumption to 44.1 mg, and the pain relief was similar to that produced in the group treated with 3 mg piritramide per bolus. The intensity of typical side effects of opioids and antipyretic analgesics (nausea, vomiting, lowering of respiratory frequency, sweating) was low and always easily controlled. The acceptance by patients, nurses, and physicians of PCA was high. PCA with on-demand intravenous injection of the combination of piritramide and metamizole improved the degree of analgesia and concomitantly reduced the opioid dose.