Further efforts to reduce postoperative pain require introduction of new analgesics into clinical practice. Oral acetaminophen, or paracetamol that is the international nonproprietary name for acetaminophen, has been well known as a safe and effective analgesic, and antipyretic for more than a century. In some contexts, it is abbreviated as APAP, for N-acetyl-para-aminophenol. However, although intravenous (IV) acetaminophen has been approved in approximately 80 countries, it is not currently available in the U.S.A.