NCIt definition : A water-soluble phosphate ester prodrug of phenytoin, a hydantoin derivative with
anticonvulsant activity. Fosphenytoin is hydrolyzed to phenytoin by phosphatases.
Phenytoin exerts its effect mainly by promoting sodium efflux and stabilizes neuronal
membranes in the motor cortex. This leads to a suppression of excessive neuronal firing
and limits the spread of seizure activity.;