Plasma protein binding of drugs and adjustment of their dosing regimen in patients with chronic renal failure.

The changes in plasma protein binding of drugs caused by chronic renal failure have been evaluated with respect to the calculation of their total plasma clearance. Theoretical analysis suggests that if the plasma protein binding of the drug is high and if it is excreted predominantly by the kidneys (e.g., cefoxitin, cloxacillin), negligible changes in the plasma protein binding caused by chronic uremia can be the source of a significant error in adjustment of its dosing regimen. A formula for the calculation of changes in total plasma clearance with respect to changes of their plasma protein binding has been recommended.