Hemodialysis of acetaminophen in uremic patients

The effect of the artificial kidney on the removal of acetaminophen was investigated in 6 chronic hemodialysis patients. Acetaminophen, 650 mg, was given orally 2 hrs prior to hemodialysis. Plasma and dialysate samples were collected periodically over 3 hours and analyzed by HPLC for acetaminophen content. Dialysis clearance was calculated by Arterial-venous difference and simultaneous dialysate measurement. The extraction efficiency of the hollow-fiber dialyzers averaged 47.5%. The mean dialysis clearance of 112 ml/min measured with blood as the body fluid of reference was confirmed by calculation of clearance using dialysate measurement. A mean of 70.5 mg of acetaminophen for 11% of the administered dose was removed during the 3 hour dialysis period. The beta phase had a mean half-life of 1.6 hours in our patients on hemodialysis compared with 2.0 hours reported for both normal patients and uremic patients. Despite the favorable extraction ratio and dialyzer clearance, the artificial kidney is not very effective in competing with the liver for removal of the parent compound acetaminophen because of the drug's short half-life and rapid hepatic metabolism. Hence, the chronic hemodialysis patient may not need a dosage adjustment during or following hemodialysis.