DISCUSSION
Overall, 12 of 14 placebo-controlled studies found that patients receiving IV acetaminophen had improved analgesia. When compared with IV parecoxib, IV metamizol, or oral ibuprofen, IV acetaminophen was found to have similar analgesic outcomes as the active comparator in 7 of the 8 studies. Parecoxib is a cyclo-oxygenase (COX)-2-specific anti-inflammatory agent not approved in the U.S.A. Metamizol is a nonsteroidal anti-inflammatory drug removed from the U.S. market in the 1970s because of its side effect profile, particularly agranulocytosis.