Paracetamol

Paracetamol (or acetaminophen) is a common drug for relieving pain. It can also be used to reduce fever, or headache, caused by a cold or a flu.

Paracetamol

Clinical data
Pronunciation	Paracetamol: /ˌpærəˈsiːtəmɒl/ (listen) Acetaminophen: /əˌsiːtəˈmɪnəfɪn/ (listen)
Trade names	Tylenol, Panadol, others[1]
Synonyms	N-acetyl-para-aminophenol (APAP), acetaminophen (USAN US)
AHFS/Drugs.com	Monograph
MedlinePlus	a681004
License data	US DailyMed: Acetaminophen US FDA: Acetaminophen
Pregnancy category	AU: A[2]
Routes of administration	Mouth, rectal, intravenous (IV)
Drug class	Analgesics and antipyretics
ATC code	N02BE01 (WHO) N02BE51 (WHO) N02BE71 (WHO)
Legal status
Legal status	AU: S4 (Rx), OTC, and unscheduled UK: General sales list (GSL, OTC) US: OTC / Rx-only
Pharmacokinetic data
Bioavailability	63–89%[3]: 73
Protein binding	negligible to 10–25% in overdose[4]
Metabolism	Predominantly in the liver[5]
Metabolites	APAP gluc, APAP sulfate, APAP GSH, APAP cys, AM404, NAPQI[6]
Onset of action	Pain relief onset by route: By mouth – 37 minutes[7] Intravenous – 8 minutes[7]
Elimination half-life	1.9–2.5 hours[4]
Excretion	Urine[4]
Identifiers
IUPAC name N-(4-hydroxyphenyl)acetamide
CAS Number	103-90-2 Y
PubChem CID	1983
PubChem SID	46506142
IUPHAR/BPS	5239
DrugBank	DB00316 Y
ChemSpider	1906 Y
UNII	362O9ITL9D
KEGG	D00217 Y C06804
ChEBI	CHEBI:46195 Y
ChEMBL	ChEMBL112 Y
PDB ligand	TYL (PDBe, RCSB PDB)
ECHA InfoCard	100.002.870
Chemical and physical data
Formula	C8H9NO2
Molar mass	151.17 g·mol−1
3D model (JSmol)	Interactive image
Density	1.263 g/cm3
Melting point	169 °C (336 °F) [8][9]
Solubility in water	7.21 g/kg (0 °C)[10] 8.21 g/kg (5 °C)[10] 9.44 g/kg (10 °C)[10] 10.97 g/kg (15 °C)[10] 12.78 g/kg (20 °C)[10] ~14 mg/ml (20 °C)
SMILES CC(=O)Nc1ccc(O)cc1
InChI InChI=1S/C8H9NO2/c1-6(10)9-7-2-4-8(11)5-3-7/h2-5,11H,1H3,(H,9,10) Y Key:RZVAJINKPMORJF-UHFFFAOYSA-N Y
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Overview

Synthesis of paracetamol from phenol.

Final step of the synthesis of paracetamol from phenol.

The IUPAC name for paracetamol is acetaminophen.^[11] Both acetaminophen and paracetamol both come from the names of the chemicals used in the compound: N-acetyl-para-aminophenol and para-acetyl-amino-phenol. Sometimes, it is shortened as APAP, for N-acetyl-para-aminophenol.

History

Harmon Northrop Morse was the first to make paracetamol, in the year 1878. Drugs made with paracetamol became common in the 1950s. Today, these drugs are some of the most used, together with those containing salicylic acid, Ibuprofen or Diclofenac. Unlike these, paracetamol has no anti-inflammatory properties. In the year 1977, paracetamol was added to the List of Essential Medicines of the WHO.

Safety

Further information: Paracetamol poisoning

Paracetamol is considered safe for use. The drug is easily available without a prescription. Patients sometimes take too much paracetamol, when they do not know how much should be taken. The recommended dose may not work for some people. Other times, it is because they are trying to commit suicide. Very often, a person's liver can be hurt when they take too much paracetamol.^[12]

A dose of 150 milligrams (mg) for every kilogram (kg) of the person's weight (about 10 grams for most adults) will lead to permanent liver damage, and may cause the liver to fail. For people whose livers have already been damaged, such as alcoholics, and for those with a limited secretion of paracetamol, this amount can be much smaller.^[13]

United Kingdom

In England and Wales, about 30,000 people per year go to the hospital after taking too much paracetamol (called paracetamol poisoning), with about 150 dying of the poisoning. Since a law was passed saying that paracetamol packets cannot be too large, fewer people have been committing suicide with paracetamol.^[14] In Great Britain^[15] and the United States Paracetamol is the main reason for acute liver failure. About half of the cases are because of an "unintentional overdose".^[12]

Mass poisoning incident in 1982

In 1982, there was a case of sabotage.^[16][17] Packets of paracetamol had been tampered with: Seven people died, because they had taken poisoned samples. As a result, the FDA made stricter regulations. Also, paracetamol-products worth 100 million US dollars were called back.