Paracetamol mechanism of action

The paracetamol is a drug used as an analgesic (pain reliever) and as an antipyretic (to reduce fever). Paracetamol (acetaminophen) is often called Tachipirina, as this is its most widespread trade name: however, it should not be forgotten that there are numerous other trade names, such as Efferalgan, Acetamol, Codamol and many others.

Paracetamol or acetaminophen (chemical name N-acetyl-para-aminophenol) is the active metabolite of phenacetin.
Paracetamol increases the threshold to painful stimuli, exerting an analgesic effect against pain of different causes and etiology.

It is available without a prescription and is used as a common self-prescription pain reliever (although reimbursement of 1000 mg acetaminophen is possible if certain conditions exist and when prescribed by prescription). The drug is available in fixed-dose combinations with narcotic and non-narcotic analgesics (including aspirin and other salicylates, barbiturates, caffeine) in preparations for vascular migraine, insomnia, toothache, antihistamines , antitussives, decongestants, expectorants, in cold and flu preparations and in treatments for sore throat.

The most used dosages of paracetamol in single preparation are 500 mg and 1000 mg. Paracetamol is a valid alternative to aspirin and other anti-inflammatories such as ibuprofen (momnet, Brufen, Nurofen), ketoprofen (Oki, Ketodolo, Arthrosilene, Fastum Gel), naproxen (Naprosyl, Momendol, Naproxene), nimesulide (Algimesil, Aulin, Ledoren), as an analgesic-antipyretic compound; however, its anti-inflammatory effects are very low when compared with pure anti-inflammatories.

In fact, although paracetamol is indicated in the treatment of pain in patients with non-inflammatory osteoarthritis, it does not represent an adequate substitute for non-steroidal anti-inflammatory drugs (NotSteroidal Anti-Inflammatory Drugs, NSAIDs) in chronic inflammatory conditions such as rheumatoid arthritis. Paracetamol is well tolerated and is associated with a low incidence of gastrointestinal side effects, which instead affects all other anti-inflammatory drugs, which can cause gastritis and gastric or duodenal ulcers.

However, an acute overdose of Tachipirina can cause severe liver damage and cases of accidental or deliberate intoxication are continuously increasing, especially for those with chronic painful conditions and who take more than 3-4 g of paracetamol for several consecutive days. Chronic use of less than 2 g / day has not been shown to be associated with hepatic dysfunction.

Paracetamol mechanism of action

Paracetamol (Tachipirina) has effects analgesics is antipyretics similar to those of aspirin and other anti-inflammatory drugs, but exerts only mild anti-inflammatory effects and is thought to poorly inhibit COX in the presence of high concentrations of peroxides, such as those found at sites of inflammation.

What is the COX? COX is short for cyclooxygenase, or prostaglandin-endoperoxide synthase, and is an enzyme (a particular type of protein) belonging to the oxidoreductase class, which stimulates the conversion of arachidonic acid into prostaglandin endoperoxide.

COX cyclooxygenases are therefore proteins responsible for the synthesis of prostaglandins, substances produced by the body that are important for the regulation of numerous biological phenomena, among which the most important are inflammation, pain sensitivity, fever, secretions from the digestive organs, filtration of fluids in the kidney, reproduction and blood clotting.

Therefore, paracetamol, unlike other inflammatory drugs (NSAIDs), has almost no action in reducing cyclooxygenase and therefore is not effective in "extinguishing" inflammation.

Surely the most commonly taken daily dose, 1000 mg, is found to inhibit just 50% of COX-1 and COX-2 in tests carried out on the blood of healthy volunteers.
It has been suggested that COX inhibition may be more pronounced in the brain, and therefore in the centers of body temperature, which could explain the effectiveness antipyretic.


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