The binding of paracetamol to plasma proteins of man and pig

The binding of N-acetyl-4-aminophenol (paracetamol) to human and porcine plasma at both toxic and therapeutic concentrations was investigated by ultrafiltration and equilibrium dialysis over the range 50–300 μg ml−1. Plasma protein binding occurred at paracetamol concentrations greater than 60 μg ml−1. The extent of protein binding at a plasma concentration of 280 μg ml−1 of the drug is between 15 and 21% for both pig and man. There is no appreciable binding to erythrocytes in either species over the whole concentration range studied.