Emergency Medicine PharmD
July 9, 2014
"IV acetaminophen was marketed on the premise that it could serve as a foundation for “multi-modal” pain control by achieving more rapid and higher plasma concentrations than the oral and rectal formulations. Theoretically, this would reduce opioid use and therefore reduce opioid related adverse events. However, this hasn't exactly panned out in clinical studies. A meta-analysis by McNicol and colleagues found a whopping reduction of 1.3 mg morphine equivalent at 6 hours among 154 post-operative patients in whom IV acetaminophen was added. Not surprisingly, they found no decrease in opioid-related adverse events. These findings were replicated in another meta-analysis by Remy and colleagues who found a 9 mg morphine equivalent reduction at 24 hours among post-operative patients. Again, there was no difference in opioid-related adverse events between groups."
Product promotional materials suggest that the threshold for analgesic effects is 16 mcg/ml (or 16 mg/L),
and the threshold for antipyretic effects is 5 mcg/mL.
http://empharmd.blogspot.com.es/2014/07/iv-acetaminophen-for-pain-management-in.html