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Natural Health News Articles
Page: 1
| Posted: 7th August 2004 |
| Acetaminophen |
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Acetaminophen (in American English), or paracetamol (in British English), is a popular analgesic and antipyretic drug that is used for the relief of fever, headaches, of other minor aches and pains. It is a major ingredient in numerous cold and flu medications and many prescription analgesics. It is remarkably safe in standard doses, but because of its wide availability, deliberate or accidental overdose is not uncommon.
Acetaminophen, unlike other common analgesics such as aspirin and ibuprofen, has no anti-inflammatory properties, and so it is not a member of the class of drugs known as non-steroidal anti-inflammatory drugs or NSAIDs. Unlike NSAIDs, in normal doses acetaminophen does not irritate the lining of the stomach, or affect blood coagulation, the kidneys or the fetal ductus arteriosus.
Mechanism of action
Acetaminophen, like aspirin and NSAIDs, works by reducing the activity of the cyclo-oxygenase 2 (COX) enzyme which produces prostaglandins. While the other drugs operate as competitive inhibitors and directly block the active site of COX, acetaminophen blocks COX indirectly. This indirect blockade is effective in the brain and endothelial cells but not in platelets and immune cells which have high levels of peroxides.
Thus, acetaminophen does not reduce inflammation or act as an anticoagulant, while aspirin does. Aspirin's unique anticoagulant effect is due to acetylation of platelet cyclooxygenase.
Toxicity
Acetaminophen single doses above 10 grams or chronic doses over 5 grams per day in a well nourished non-consumer of alcohol, or above 4 grams per day in a poorly nourished consumer of alcohol, can cause significant injury to the liver. Without timely treatment, acetaminophen overdoses can lead to liver failure and death within days. Because of the wide over-the-counter availability of the drug, it is often used in suicide attempts.
Acetaminophen should not be taken after alcohol consumption, because the liver, when engaged in alcohol breakdown, cannot properly dispose of acetaminophen, thus increasing the risk of hepatotoxicity.
Risk factors for toxicity
The toxic dose of acetaminophen is highly variable. |
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