(1989; 60 pages) [French]
Group: non-opioid analgesic
Tablet: 100-500 mg
Suppository: 100 mg
Syrup: 125 mg in 5 ml
Paracetamol is a synthetic derivative of p-aminophenol with analgesic and antipyretic activity but no anti-inflammatory action. Its plasma half-life is about 2 hours. It is extensively metabolized in the liver and subsequently excreted in the urine.
Symptomatic relief of mild to moderate pain.
Dosage and administration
Adults: 0.5-1 g repeated, as necessary, every 4-6 hours to a maximum of 4 g daily.
Children: 20-30 mg/kg daily in divided doses.
Dosage should be reduced in patients with renal failure.
Suppositories are available for patients unable to take the drug orally.
Treatment should not be continued for more than 5 days except on medical advice.
• Hypersensitivity to paracetamol.
• Repeated administration is contraindicated in patients with hepatic insufficiency.
At doses within the therapeutic range paracetamol is usually well tolerated.
Hypersensitivity, dermatological reactions, neutropenia and thrombocytopenic purpura have rarely been reported.
In overdosage paracetamol is dangerously hepatotoxic; potentially fatal hepatic necrosis can occur after ingestion of as little as a single dose of 10-15 g. Signs of mild gastrointestinal irritation are commonly followed 2 days later by anorexia, nausea, malaise, abdominal pain, progressive evidence of liver failure and, ultimately, hepatic coma.
Gastric lavage should be performed or emesis induced whenever there is a possibility that paracetamol remains in the stomach. When feasible, plasma paracetamol concentrations should be determined to assess the risk of liver failure. This is likely when the plasma concentration is greater than 200 micrograms/ml at 4 hours after ingestion, 100 micrograms/ml at 8 hours, 50 micrograms/ml at 12 hours, 25 micrograms/ml at 16 hours and 6 micrograms/ml at 24 hours.
Either methionine or acetylcysteine may be used as a specific antidote. To be effective the antidote must be administered within 16 hours and before signs of hepatic damage become evident. A loading dose of 140 mg/kg administered orally or through a nasogastric tube is supplemented by 70 mg/kg every 4 hours until the results of liver function tests have returned to normal. If this has not occurred within 3 days, no further improvement can be expected.
Fluid and electrolyte balance must be maintained and ventilation must be assisted when respiration is depressed.
Paracetamol tablets and syrup should be stored in tightly closed containers protected from light, below 25°C. Suppositories should be stored below 15°C.