Abstract
Background. Intravenous (IV) acetaminophen is used in multimodal analgesia to reduce the amount and duration of opioid use in the postoperative setting. Methods. A systematic review of published randomized controlled trials was conducted to define the opioid-sparing effect of IV acetaminophen in different types of surgeries. Eligible studies included prospective, randomized, double-blind trials of IV acetaminophen compared with either a placebo- or active-treatment group in adult (age >18 years) patients undergoing surgery. Trials had to be published in English in a peer-reviewed journal. Results. A total of 44 treatment cohorts included in 37 studies were included in the systematic analysis. Compared with active- or placebo-control treatments, IV acetaminophen produced a statistically significant opioid-sparing effect in 14 of 44 cohorts (32%). An opioid-sparing effect was more common in placebo-controlled comparisons. Of the 28 placebo treatment comparisons, IV acetaminophen produced an opioid-sparing effect in 13 (46%). IV acetaminophen produced an opioid-sparing effect in only 6% (one out of 16) of the active-control groups. Among the 16 active-control groups, opioid consumption was significantly greater with IV acetaminophen than the active comparator in seven cohorts and not significantly different than the active comparator in eight cohorts. Conclusions. The results of this systematic analysis demonstrate that IV acetaminophen is not effective in reducing opioid consumption compared with other adjuvant analgesic agents in the postoperative patient. In patients where other adjuvant analgesic agents are contraindicated, IV acetaminophen may be an option.