Does Phenytoin Require TDM?

Does Phenytoin Require TDM? Therapeutic drug monitoring of phenytoin is necessary to ensure therapeutic and nontoxic levels. Hypoalbuminemia, renal failure, and interactions with other highly protein-bound drugs (e.g., valproic acid) alter protein binding of phenytoin. Do you administer phenytoin on an empty stomach? This medicine can be taken with food or on an empty stomach.