Paracetamol and its metabolites in saliva and plasma in chronic dialysis patients

1 Many pharmacokinetic studies on paracetamol are based on saliva paracetamol concentrations. The utility of saliva in patients with chronic renal failure is unclear. In this study, concentrations of saliva and plasma paracetamol and its major metabolites, sulphate and glucuronide conjugates were determined at 0.5, 1, 2 and 3 h after the ingestion of 1 g paracetamol in 20 patients with end‐stage renal failure. Ten haemodialysis patients were studied on a non‐haemodialysis day and during a haemodialysis session. The other 10 patients were on chronic ambulatory peritoneal dialysis. 2 The plasma paracetamol concentrations attained in all groups were not different from those reported previously in healthy subjects. Mean±s.d. plasma paracetamol concentrations at 0.5 h in haemodialysis patients on a non‐haemodialysis day, during haemodialysis and in those on chronic ambulatory peritoneal dialysis were 15.3±8.2, 21.5±10.9 and 18.2±12.3 μg ml‐1 respectively. 3 The saliva paracetamol concentrations were highly variable and unpredictable. Saliva paracetamol concentrations at 1, 2 and 3 h after ingestion in the haemodialysis group during haemodialysis were 31.5±20.1, 14.1±10.4 and 7.3±3.8 μg ml‐1 respectively, significantly (P