Due to the avoidance of first-pass metabolism, Ofirmev exposes the liver to approximately 50% less acetaminophen compared with equivalent doses of oral acetaminophen. The maximum blood concentration (Cmax) of Ofirmev is higher than with oral or rectal administration however, it is important to note that the Cmax with Ofirmev (29 mcg/mL) remains far below the 150 mcg/ mL concentration considered potentially hepatotoxic.ĭespite the difference in Cmax, overall volume of distribution and area under the curve (AUC) values remain similar for all acetaminophen formulations. 1,3,4 The duration of action of Ofirmev for analgesia is 4 to 6 hours, and 6 or more hours for antipyresis.

The peak analgesic effect is reached at approximately 1 hour. The onset of action of Ofirmev occurs at approximately 15 minutes for analgesia and within 30 minutes for antipyresis. The mechanism by which Ofirmev exerts its antipyretic and analgesic effects is not precisely known however, it is thought to be centrally mediated. This, as well as shortterm, postoperative opioid augmentation, may be 2 practice areas where IV acetaminophen can play a role.

However, IV administration of analgesics is often preferred immediately postoperatively when a faster onset of pain relief is desired, or when oral or rectal routes of administration are not options. With so many formulations available, the place in therapy for Ofirmev is often unclear. Intravenous (IV) acetaminophen (Ofirmev), manufactured by Cadence Pharmaceuticals, is FDA approved for use in management of mild-to-moderate pain, moderate-to-severe pain with adjunctive opioid analgesics, and reduction of fever in patients 2 years and older.1,2 Acetaminophen is one of the most widely used, well-known analgesic agents available in a wide variety of dosage forms, including the IV formulation which was approved for use in the United States in November 2010.

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