Paracetamol is one of the most popular over-the-counter analgesic preparations, used regularly by millions of people throughout the world. It is also an ingredient of other brand name analgesic preparations, for example calpol, anadin extra and lemsip.
- has a unique clinical pharmacological profile that includes potent analgesic and antipyretic effects and no or little anti-inflammatory activity as well as minor gastrointestinal, renal, and vascular side effects (1)
- typical licensed indications for paracetamol in adults include treatment of most painful and febrile conditions, including headache, neuralgia, sore throat, and rheumatic pain (2)
- acetaminophen (paracetamol; N-acetyl-p-aminophenol) is the active metabolite of phenacetin
- unlike phenacetin, paracetamol is not carcinogenic (1)
- oral paracetamol has excellent bioavailability with peak plasma concentrations occurring within 30-60 min after ingestion
- plasma t1/2 is about 120 min
- binds to plasma proteins less than NSAIDs and diffuses throughout most body fluids.
Potential risk factors for hepatotoxicity with paracetamol include (2):
- dry body weight under 50 kg
- use of paracetamol in older or frail patients
- cachexia
- renal insufficiency
- chronic malnutrition
- chronic dehydration
- decompensated liver disease
- chronic alcohol consumption or regular consumption of alcohol in excess of recommended amounts
- long term treatment with liver enzyme inducing drugs, such as
- carbamazepine, phenytoin, primidone, rifampicin, phenobarbital, St John's Wort, or other drugs that induce liver enzymes
Reference:
- Freo U, Ruocco C, Valerio A, Scagnol I, Nisoli E. Paracetamol: A Review of Guideline Recommendations. J Clin Med. 2021 Jul 31;10(15):3420. doi: 10.3390/jcm10153420. PMID: 34362203; PMCID: PMC8347233.
- Caparrotta T M, Carduff E, Dear J W. Paracetamol use in adults BMJ 2023; 383 :e070753 doi:10.1136/bmj-2022-070753