Fosphenytoin.

Fosphenytoin is a phenytoin prodrug that has been introduced to overcome some of the problems and limitations associated with parenteral phenytoin sodium administration. Fosphenytoin is a phosphate ester prodrug that is converted to phenytoin in vivo by peripheral esterases. Fosphenytoin has several advantages and disadvantages that should be considered when selecting its use in place of parenteral phenytoin. Advantages with fosphenytoin include better tolerability, improved safety, better stability, ability for intramuscular administration, and faster infusion rates. Disadvantages with fosphenytoin include rate and dose related paresthesias and pruritus, delayed decreases in blood pressure, the potential for therapeutic drug monitoring errors, and higher drug acquisition costs. In general, given the pros and cons of the new drug, fosphenytoin offers an attractive alternative for parenteral phenytoin in select individuals.