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Pharmacology: Pharmacodynamics: Paracetamol produces antipyresis through action on the hypothalamic heat-regulating center and analgesia by elevation of the pain threshold.
Pharmacokinetics: Paracetamol is readily absorbed from the gastrointestinal tract with peak plasma concentration occurring about 30 minutes to 2 hours after ingestion. It is metabolised in the liver and excreted in the urine as the glucuronide and sulphate conjugates. Less than 5% is excreted as unchanged Paracetamol. The elimination half-life varies from about 1 to 4 hours. Plasma protein binding is negligible at usual therapeutic concentrations but increases with increasing concentrations. It is reported that the binding of paracetamol to plasma protein did not occur with plasma concentrations of less than 60 mg per ml, corresponding to the usual therapeutic concentration. After toxic doses of paracetamol, up to 43% could be bound to plasma proteins.
