1. The metabolism of [3H]paracetamol has been studied in the perfused rat kidney. Seventy-four per cent of filtered paracetamol was reabsorbed. Paracetamol appeared in the urine; 90%was unaltered but 10%appeared as metabolites: the glucuronide, sulphate, mercapturic acid and cysteine conjugates.
2. At concentrations of paracetamol of 1–3 mmol/l no impairment of renal physiological function was observed.
3. The presence of the mercapturic acid and cysteine conjugates in the urine demonstrates the capacity of the kidney for oxidative metabolism of paracetamol and hence the formation of potentially toxic intermediates.