Limitations
Our systematic review had several limitations, including those that relate to the general use of a systematic review and others that pertain specifically to surgical analgesia studies. In only 5 of 16 studies did the acetaminophen group size exceed 40 patients. Small sample sizes studies are unlikely to identify rare but clinically relevant adverse effects. Because the best analgesic approach needs to be individualized to the specific surgical procedure, results from a specific study may not be applicable to other surgery types or when other analgesic interventions such as nerve blocks are added to a multimodal approach.12 In addition, the studies used different systems for reporting the severity and duration of pru-ritus,nausea,and vomiting. Publication bias also cannot be excluded.Also,none of the active comparator studies included often used nonsteroidal anti-inflammatory drugs such as ketorolac, ketoprofen, or diclofenac.
Intravenous Acetaminophen An FDA advisory committee recommended in 2009 to reduce the maximum daily dose of oral acetaminophen to less than 4 g because of concerns primarily related to hepatotoxicity from acetaminophen overdose.13 The FDA expressed concern that the relatively free over-the-counter access to acetaminophen-containing products and the lack of healthcare provider control in the outpatient setting were part of the problem. These access and control issues should not apply to IV acetaminophen in the inpatient hospital setting in which it will be administered.
The faster onset of IV acetaminophen compared with oral or rectal administration should be helpful when treating acute surgical pain particularly when oral intake is not possible.In aggregate,the 16 RCTs selected for analysis indicate that IV acetaminophen is an effective analgesic in a variety of surgical procedures.