Antiepileptic drugs (AEDs) are cleared from the circulation by hemodialysis, principally by diffusion from the blood into the dialysate through the filter membrane. The drug moves from the blood (high concentration) to the dialysate (low concentration) via a concentration gradient. (The principles applicable to hemodialysis also apply to peritoneal dialysis.)
Many factors determine the rate of clearance of a drug during hemodialysis:29
There is no simple equation to predict the amount of an AED that will be lost during dialysis. Drugs that are water-soluble, not highly protein-bound, and that have a small volume of distribution are readily removed by hemodialysis. Drugs with high lipid solubility (i.e., low water solubility), high protein binding, and high volume of distribution will be difficult to remove by hemodialysis.
See Table: Risk of Drug Removal By Hemodialysis for a listing of risk of drug removal by hemodialysis for various AEDs. Note that some removal occurs during dialysis even for “low-risk" drugs.
Adapted from: Browne TR. Renal disorders. In: Ettinger AB and Devinsky O, eds. Managing epilepsy and co-existing disorders. Boston: Butterworth-Heinemann; 2002;49-62. With permission from Elsevier (www.elsevier.com).
Reviewed and revised February 2004 by Steven C. Schachter, MD, epilepsy.com Editorial Board.
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