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.