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 Cchange= 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.