Intravenous administration of propacetamol reduces morphine consumption after spinal fusion surgery.

We sought to determine the analgesic efficacy, opioid-sparing effects, and tolerability of propacetamol, an injectable prodrug of acetaminophen, in combination with morphine administered by patient-controlled analgesia (PCA) after spinal fusion surgery. Forty-two patients undergoing spinal stabilization surgery were randomized into two groups, which were given either an IV placebo or an IV injection of 2 g propacetamol every 6 h for 3 days after surgery. The postoperative opioid analgesic requirement was assessed with a PCA device used to self-administer morphine. Pain relief was evaluated by a visual analog pain scale and by verbal rating scores of pain relief at 8-h intervals for up to 72 h after surgery. The cumulative dose of morphine at 72 h was smaller in the Propacetamol group than in the Placebo group (60.3 +/- 20.5 vs 112.2 +/- 39.1 mg; P < 0.001). The pain scores were significantly lower in the Propacetamol group measured at two intervals of the study, although visual analog scale pain intensity scores were smaller than 3 in both groups. Most patients in the Placebo group obtained a greater degree of sedation on postoperative Day 3 (P < 0.05). This study demonstrates the usefulness of propacetamol as an adjunct to PCA morphine in the treatment of postoperative pain after spinal fusion.