2g daily dose of IV acetaminophen reduces opioid use in post-orthopaedic surgery pain: Study

The study model was a multicenter, randomized, double-blind, placebo-controlled phase III trial. Researchers enrolled 235 patients who underwent orthopedic surgery and randomly assigned them to receive intravenous acetaminophen 500 mg every 6 h or a placebo. Postoperative morphine consumption, pain intensity at rest and during movement, and adverse events were analyzed.

Key findings of the study,

• The patients in the acetaminophen group consumed significantly less morphine than the placebo group [8.7 mg vs. 11.2 mg] during the first 24 h after surgery.

• In the modified intention-to-treat analysis, the mean amount of consumed morphine was 8.7 mg in the acetaminophen group compared to 11.2 mg in the placebo group. The difference in mean values was 2.5 mg.

• The per-protocol analysis demonstrated that the consumed morphine was 8.3 mg and 11.7 mg in the acetaminophen group and the placebo group, respectively. The difference in means: 3.4 mg.

• The two groups did not differ significantly in terms of pain intensity and adverse events.

The authors conclude that intravenous acetaminophen at a daily dose of 2 g can reduce morphine consumption by adults within the first 24 h after orthopedic surgery, but the extent of reduction is not clinically relevant.

Reference:

Yin F, Ma W, Liu Q, Xiong LL, Wang TH, Li Q, Liu F. Efficacy and safety of intravenous acetaminophen (2 g/day) for reducing opioid consumption in Chinese adults after elective orthopedic surgery: A multicenter randomized controlled trial. Front Pharmacol. 2022 Jul 22;13:909572. doi: 10.3389/fphar.2022.909572