Preoperative oral administration of fast-release morphine sulfate reduces postoperative piritramide consumption

The aim of this prospective randomized placebo-controlled double-blind study was to investigate the effect of premedication with morphine sulfate on postoperative pain. Ninety-eight ASA I-III patients undergoing total replacement of the knee or hip joint were randomly assigned to one of two groups. Group 1 received 20 mg morphine sulfate p.o. approximately one hour before the start of surgery; group 2 received placebo. After surgery, piritramide was administered via patient-controlled analgesia over 24 hours. Piritramide consumption and pain scores (visual analog scale) were recorded. The duration of surgery (mean +/- SD) was comparable in the two groups (group 1: 145 +/- 42 min, group 2: 131 +/- 35 min). In group 1 the cumulative piritramide consumption during 24 hours postoperation was significantly less than in the placebo group (37.5 +/- 12.5 mg versus 46.8 +/- 22.1, t-test, p < 0.05), although similar pain scores were recorded (group 1: 4.8 +/- 1.8 and 3.6 +/- 1.7, group 2: 4.8 +/- 1.6 and 3.4 +/- 2.0, at 1 and 24 hours, respectively). These data show that the preoperative oral administration of morphine sulfate, regardless of its short half-life, can reduce postoperative consumption of opioids at similar pain levels.