Correction for drug loss during hemodialysis

The plasma concentration of a drug that has been partially removed during dialysis can be restored to the desired level using the following equation to calculate a loading dose (LD) of the drug:

Where C_change= desired change in plasma concentration and VD= volume of distribution

For example, to increase the plasma concentration of phenytoin by 5 mg/L (5mcg/mL), the clinician would multiply 5 mg/L by the phenytoin volume of distribution, 0.7L/kg, resulting in a loading dose of 3.5 mg/kg.

For gabapentin, levetiracetam, and topiramate, a standard replacement dose is recommended after hemodialysis. See the section on each drug for details.

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.