Hemodialysis clearance and total body elimination of carbamazepine during chronic hemodialysis.

The effect of the artificial kidney on the removal of carbamazepine was studied in four uremic patients undergoing chronic hemodialysis. Each patient received 500 mg of carbamazepine PO 8 hr prior to hemodialysis. Predialysis and postdialysis blood samples as well as dialysate samples were collected at various time intervals during a 4-hr hemodialysis. Samples were analyzed for carbamazepine content by HPLC. Dialysis clearance calculated from dialysate measurements averaged 53.6 +/- 10.0 mL/min which is double the reported mean plasma clearance of 27.5 mL/min. Since drug clearance by the dialyzer is twice the endogenous plasma clearance, we conclude that carbamazepine is dialyzable. Despite the significant dialysis clearance, a dosage regimen adjustment may not be necessary because of the long elimination half-life of carbamazepine of 35 hr compared to the short length of the usual hemodialysis treatment of 3-5 hr.