Fosphenytoin is a water-soluble phenytoin prodrug that is administered intravenously to deliver phenytoin, potentially more safely than intravenous phenytoin. It is most commonly used in the acute treatment convulsive status epilepticus. Fosphenytoin, phosphate ester pro-drug of phenytoin, was developed to overcome complications associated with parenteral phenytoin administration in treatment of acute symptomatic seizures, short-term prophylaxis and treatment of repetitive or prolonged seizures and status epilepticus. One millimole of phenytoin is produced for every millimole of fosphenytoin administered; the hydrolysis of fosphenytoin also yields phosphate and formaldehyde, the latter of which is subsequently metabolized to formate, which is in turn metabolized by a folate dependent mechanism.