Fosphenytoin: current place in therapy

Fosphenytoin is a parenteral phosphate ester prodrug of phenytoin developed to overcome the limitations associated with parenteral administration of phenytoin. Despite potential clinical advantages, pharmacoeconomic concerns have prevented widespread substitution of parenteral phenytoin with fosphenytoin. The purposes of this descriptive review are to (1) highlight recent clinical and pharmacoeconomic data regarding the therapeutic decision to use phenytoin or fosphenytoin for the parenteral management of acute seizures, and (2) discuss the implications of fosphenytoin use in neonatal and pediatric patients. Supporting recent, multidisciplinary, consensus guidelines, it is our opinion that each patient should be evaluated individually to identify those who will benefit most from fosphenytoin. Such patients may include those without intravenous or enteral access, those requiring parenteral therapy with tenuous peripheral intravenous access, and pediatric and neonatal patients. Additionally, institution-specific cost analyses should be done to assure the most appropriate agent is being used, while being sensitive to the potential disparate risk profiles between patient populations. Until the issues of safety relative to cost are objectively ameliorated, individual clinicians will likely use their own experience to dictate the place of fosphenytoin in their respective practices.