State of the art of paracetamol in acute pain therapy.

PURPOSE OF REVIEW: This review highlights new insights into the mechanism of action of paracetamol (acetaminophen) and therapeutic schemes. RECENT
FINDINGS: Paracetamol, a centrally acting inhibitor of cyclooxygenases, has weak peripheral effects recently demonstrated. Paracetamol is nevertheless devoid of side effects commonly observed with the use of nonsteroidal anti-inflammatory drugs. Paracetamol is available by the oral, rectal, and, more recently, intravenous routes of administration. Paracetamol efficacy is surgical procedure dependent. The analgesic efficacy of a 2-g starting dose of intravenous paracetamol is superior to the recommended dose of 1 g in terms of magnitude and duration of analgesic effect. The usual scheme of administration (1 g every 6 hours) has a less than 10-mg sparing effect on 24-hour morphine consumption and consequently does not significantly reduce morphine side effects. The combination of nonsteroidal anti-inflammatory drugs and paracetamol is more effective than paracetamol alone, but the benefit is unclear when compared with nonsteroidal anti-inflammatory drugs used alone.
SUMMARY: Further studies are required to assess the opioid-sparing effect and complementary analgesic effect of new intravenous paracetamol therapeutic schemes.