Paracetamol (acetaminophen)

Non-narcotic.

Analgesic-antipyretic.

Weak anti-inflammatory.

Oral administration gives peak plasma levels in 30-60 minutes.

May be given iv.

Conjugated by the liver.

Half life in therapeutic doses is 2 - 4 hours.

Half life in toxic doses in 4 -8 hours.

Side effects uncommon at normal doses, allergic skin reactions, long term risk of renal damage.

Toxic dose is 2 to 3 times therapeutic dose.

Hepatotoxicity.

Possible renal toxicity.

Conjugating liver enzymes become saturated.

Reacts with oxidases to produce a toxic metabolite, benzoquinone.

Toxic doses cause,

Nausea and vomiting.

After 24 – 48 hours,

Toxic metabolite reacts with liver cell proteins and kills the cells.

Widespread liver necrosis.

Complete liver failure.

Treat with gastric lavage.

Oral activated charcoal.

Treat early with intravenous acetylcysteine (parvolex).

Antidotes later than 24 hours are of less value.

Chronic alcohol consumption increases the rate of toxic metabolite production