Fatal cerebral blødning på grund af mulig interaktionmellem paracetamol og warfarin

This is a case report of an 83-year-old man in warfarin treatment with stable international normalised ratio (INR) after aortic valve replacement and atrial fibrillation. Due to back pain he took paracetamol (acetaminophen) 4 g/day, morphine 30 mg/day and diclofenac as rescue medication for two weeks. After 14 days of treatment he was admitted to a hospital with acute neurological deficits, and a blood sample showed INR levels above 10. A CT-scan of the brain showed an intracerebral haemorrhage. The patient died eight days after admission. Mechanisms of the possible interaction between paracetamol and warfarin are discussed.