A pharmacokinetic interpretation of increasing concentrations of DEHP in haemodialysed patients

The degree of exposure to DEHP was assessed in 11 patients with chronic ren al failure undergoing maintenance haemodialysis. The amount of DEHP leached from the dialyser during a 4-h dialysis session was estimated by monitorin g the DEHP blood concentration using a HPLC method. When a patient undergoe s a dialysis treatment, the concentration of di-2-ethylhexyl phthalate (DEH P) in venous blood is increased when the blood crosses through the dialysis apparatus. This increase may be explained either because DEHP is not extra cted by the dialyser or because DEHP comes from the dialysis bath due to co ntact of blood against plasticized pipes. To explain the increasing concent ration of DEHP during treatment of renal failure using plasticized tubing, we propose a pharmacokinetic compartmental model in order to fit raw data o btained from dialysed patients and to get the amount of DEHP which enters t he body by AUC calculations. Results obtained after HPLC analysis show a hi gh degree of interpatient variability in DEHP retained. This amount can rea ch a toxicity level because of repetitive dialysis treatments over prolonge d periods of time. In the coming years, it seems necessary to reconsider th e use of DEHP as a plasticizer in medical devices. Highly unacceptable amou nts of DEHP leached during the dialysis session could be easily avoided by careful selection of haemodialysis tubing. (C) 2000 IPEM. Published by Else vier Science Ltd. All rights reserved.