Where plasma albumin is reduced, free phenytoin may provide a better indication of drug toxicity than total (measured) phenytoin.
"Albumin-adjusted phenytoin" and "Free phenytoin" are calculated using the modified Scheiner-Tozer equation taking into account renal function and assuming 90% protein binding.
Ref: Chesher D. Calculated free Phenytoin and Albumin adjusted Total Phenytoin versus measured free phenytoin. Pathology vol 51, Supp 1, S108, Feb 2019 |