[Liver and renal tolerance to paracetamol: 3 g or 4 g per day?]

To compare the hepatic and renal safety profiles of two daily dosage regimens of paracetamol (acetaminophen) (3 g versus 4 g) in patients with painful chronic rheumatoid diseases.

Medical files of outpatients in the United Kingdom were investigated using an automated database. Two acetaminophen groups (3 g and 4 g) were compared with regard to demographic variables, treatments, associated diseases and occurrence of hepatorenal adverse events. Variables collected from the files for selected patients were also analyzed using the decision tree method to identify the specific variables best explaining the occurrence of hepatorenal adverse events.

A total of 1.5 million medical files were investigated. Of the 7781 patients identified with paracetamol prescriptions for chronic rheumatoid disorders, 1868 (24%) were treated with 3 g/day and 5913 (76%) with 4 g/day. The mean overall duration of paracetamol exposure was 277 and 201 days respectively. No difference between the two acetaminophen groups was found with the numbers of patients with hepatorenal adverse events potentially related to acetaminophen intake (0.86%: group 3 g versus 0.68% group 4 g). Using the decision tree method, daily dosage of paracetamol (3 g or 4 g) was never identified as a discriminating variable capable of explaining the occurrence of hepatorenal adverse events.

When risk factors are taken into account, such as concomitant chronic diseases, both daily dosages of paracetamol (3 g and 4 g) have a comparable hepatorenal safety profiles in rheumatology, even in elderly patients.