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Phenytoin Resources
Phenytoin PharmakokineticsPlasma Protein Binding: 90% (87-93)
Phenytoin Plasma half-life in man after intravenous administration ranges from 10 to 15 hours.
Optimum control without clinical signs of toxicity occurs most often with serum levels between 10 and 20 mcg/mL.
Phenytoin is metabolized by the cytochrome P450 enzymes CYP2C9 and CYP2C19.
Phenytoin is a potent inducer of hepatic drug-metabolizing enzymes.
Phenytoin can have both zero order and first order kinetics -
(a) at low conc - it has first order kinetics (same
proportion of drug is metabolized with increasing concentration)
(b) at high conc - it has zero order kinetics ((same
amount of drug is metabolized with increasing concentration)