Is IV APAP Better Than Oral?

January 29, 2018

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There was no advantage to giving IV over oral acetaminophen for pain in the ED.

Why does this matter?
IV acetaminophen has been studied in comparison with IV opiates and other analgesic agents.  But to justify the increased cost for the IV form, it needs to be proven superior to oral therapy.  Use of an IV non-opiate is attractive, but does it work?

IV Ty-la-la
This was a small, single center, double blinded RCT comparing IV to oral acetaminophen (APAP, aka paracetamol) for acute pain in ED adult patients.  They found no significant difference in pain improvement with IV vs oral APAP at 30 minutes on a 100mm visual analog scale – both improved it modestly but equally.  There was a non-significant trend to improvement at the later time measurements, especially IV.  If anything, the 30 minute assessment should have favored the IV form, since it has immediate peak levels and no first-pass metabolism.  Another issue is that IV APAP was administered, as recommended, over 15 minutes.  One wonders how this may have affected efficacy at 30 minutes.  Finally, each group, IV and oral, required rescue IV opiates about 85% of the time, which seemed to indicate that neither form resulted in adequate pain relief alone.  This small trial showed IV APAP wasn’t more helpful than oral APAP for ED pain control.

Source
Intravenous versus oral paracetamol for acute pain in adults in the emergency department setting: a prospective, double-blind, double-dummy, randomised controlled trial. Emerg Med J. 2017 Dec 15. pii: emermed-2017-206787. doi: 10.1136/emermed-2017-206787. [Epub ahead of print]

Peer reviewed by Thomas Davis, MD.