Brands, Medical Use, Clinical Data
- Analgesics, Non-Narcotic
- Tablet (effervescent)
Brands / Synonyms
Abenol; Abensanil; Acamol; Accu-Tap; Acephen; Aceta Elixir; Aceta Tablets; Acetagesic; Acetalgin; Acetaminofen; Acetaminophen with Codeine; Acetaminophen, Aspirin and Codeine; Acetaminophen, Caffeine and Dihydrocodeine; Actamin; Actimol; Algotropyl; Allay; Alpiny; Alpinyl; Alvedon; Amadil; Aminofen; Anacin; Anacin-3; Anaflon; Anapap; Anelix; Anexsia; Anhiba; Anoquan; Apacet; Apadon; Apamid; Apamide; APAP; Apo-Acetaminophen; Atasol; Bancap; Banesin; Bayer Select; Bickie-mol; Bucet; Butalbital and Acetaminophen; Butalbital, Acetaminophen and Caffeine; Butalbital, Acetaminophen, Caffeine, and Codeine; Butapap; Calpol; Capital and Codeine; Captin; Cetadol; Clixodyne; Co-Gesic; Codrix; Conacetol; Dafalgan; Dapa; Dapa X-S; Darvocet; Darvocet-N; Datril; DHC Plus; Dimindol; Dirox; Disprol; Dolene AP-65; Doliprane; Dolprone; Drixoral Plus; Dularin; Duradyne DHC; Dymadon; Dypap; Elixodyne; Enelfa; Eneril; Esgic; Esgic-Plus; Eu-Med; Excedrin; Exdol; Febridol; Febrilix; Febrinol; Febro-Gesic; Febrolin; Femcet; Fendon; Feverall; Fevor; Finimal; Fioricet; Fioricet with Codeine; Flextra-650; Gelocatil; Genapap; Genebs; Hedex; Homoolan; Hy-Phen; Hycomine; Hydrocet; Hydrocodone and Acetaminophen; Injectapap; Janupap; Korum; Lestemp; Liquagesic; Liquiprin; Lonarid; Lorcet-Hd; Lortab; Lortab Elixir; Lyteca; Medigesic Plus; Momentum; Multin; NAPA; Napafen; Napap; Naprinol; Nealgyl; Nebs; Neopap; Neotrend; Nobedon; Norcet; Norco; Oraphen-PD; Ortensan; Oxycet; Oxycodone and Acetaminophen; Pacemo; Painex; Paldesic; Panadol; Panaleve; Panasorb; Panets; Panex; Panofen; Papa-Deine; Paracet; Paracetamol; Paracetamolo; Paracetanol; Parapan; Paraspen; Parelan; Parmol; Pasolind; Pasolind N; Pedric; Pentazocine and Acetaminophen; Percocet; Phenaphen; Phenaphen Caplets; Phendon; Phrenilin; Phrenilin Forte; Prompt; Propacet 100; Propoxyphene and Acetaminophen; Propoxyphene Napsylate and Acetaminophen; Proval #3; Pyrinazine; Redutemp; Rivalgyl; Robigesic; Rounox; Roxicet; Roxilox; Salzone; Sedapap; Servigesic; SK-Apap; Snaplets-FR; St. Joseph Fever Reducer; Suppap; Synalgos-Dc-A; Tabalgin; Talacen; Tapanol; Tapar; Tavist Allergy/Sinus/Headache; Temlo; Tempanal; Tempra; Tencon; Tibinide; Tibizide; Tisin; Tisiodrazida; Tizide; Tralgon; Tramadol and Acetaminophen; Triad; Triaprin; Tussapap; Tycolet; Tylenol; Tylenol with Codeine; Tylox; Tylox-325; Ultracet; Valadol; Valgesic; Valorin; Valorin Extra; Vicodin; Vicodin ES; Vicodin HP; Wygesic
; Zebutal; Zegesic; Zydone
For temporary relief of fever and minor aches and pains.
Acetaminophen (USAN) or Paracetamol (INN) is a popular analgesic and antipyretic drug that is used for the relief of fever, headaches, and other minor aches and pains. It is a major ingredient in numerous cold and flu medications and many prescription analgesics. It is extremely safe in standard doses, but because of its wide availability, deliberate or accidental overdoses are not uncommon. Acetaminophen, unlike other common analgesics such as aspirin and ibuprofen, has no anti-inflammatory properties or effects on platelet function, and so it is not a member of the class of drugs known as non-steroidal anti-inflammatory drugs or NSAIDs. In normal doses acetaminophen does not irritate the lining of the stomach nor affect blood coagulation, the kidneys, or the fetal ductus arteriosus (as NSAIDs can). Like NSAIDs and unlike opioid analgesics, acetaminophen does not cause euphoria or alter mood in any way. Acetaminophen and NSAIDs have the benefit of being completely free of problems with addiction, dependence, tolerance and withdrawal. Acetaminophen is used on its own or in combination with pseudoephedrine, dextromethorphan, chlorpheniramine, diphenhydramine, doxylamine, codeine, hydrocodone, or oxycodone.
Mechanism of Action
Acetaminophen is thought to act primarily in the CNS, increasing the pain threshold by inhibiting both isoforms of cyclooxygenase, COX-1 and COX-2, enzymes involved in prostaglandin (PG) synthesis. Unlike NSAIDs, acetaminophen does not inhibit cyclooxygenase in peripheral tissues and, thus, has no peripheral anti-inflammatory affects. While aspirin acts as an irreversible inhibitor of COX and directly blocks the enzyme's active site, studies have found that acetaminophen indirectly blocks COX, and that this blockade is ineffective in the presence of peroxides. This might explain why acetaminophen is effective in the central nervous system and in endothelial cells but not in platelets and immune cells which have high levels of peroxides. Studies also report data suggesting that acetaminophen selectively blocks a variant of the COX enzyme that is different from the known variants COX-1 and COX-2. This enzyme is now referred to as COX-3. Its exact mechanism of action is still poorly understood, but future research may provide further insight into how it works.
Rapid and almost complete
Oral, mouse: LD50 = 338 mg/kg; Oral, rat: LD50 = 1944 mg/kg. Acetaminophen is metabolized primarily in the liver, where most of it is converted to inactive compounds by conjugation with sulfate and glucuronide, and then excreted by the kidneys. Only a small portion is metabolized via the hepatic cytochrome P450 enzyme system. The toxic effects of acetaminophen are due to a minor alkylating metabolite (N-acetyl-p-benzo-quinone imine), not acetaminophen itself nor any of the major metabolites. This toxic metabolite reacts with sulfhydryl groups. At usual doses, it is quickly detoxified by combining irreversibly with the sulfhydryl group of glutathione to produce a non-toxic conjugate that is eventually excreted by the kidneys. The toxic dose of paracetamol is highly variable. In adults, single doses above 10 grams or 140 mg/kg have a reasonable likelihood of causing toxicity. In adults, single doses of more than 25 grams have a high risk of lethality.
Biotrnasformation / Drug Metabolism
Approximately 90 to 95% of a dose is metabolized in the liver via the cytochrome P450 enzyme pathways (primarily by conjugation with glucuronic acid, sulfuric acid, and cysteine). An intermediate metabolite is hepatotoxic and most likely nephrotoxic and can accumulate after the primary metabolic pathways have been saturated.
Acetaminophen should not be administered to patients who have previously exhibited hypersensitivity to it.
No information provided.