ABSTRACT
Parenteral phenytoin is an effective agent used to manage seizures, but it is associated with adverse effects and must be given intravenously. Fosphenytoin is higher in drug cost, but is more soluble, better tolerated and can be infused at rates three times that of phenytoin. When infusion rate is not an issue the adverse effect risk becomes a focus of concern, as well as cost. The determination of the point at which the treatment costs of infusion-related adverse effects of phenytoin outweigh the drug costs of fosphenytoin has been attempted through various clinical economic analyses. Strategies developed to promote the safe use of intravenous phenytoin are based on patient selection, recommended administration methods and patient monitoring. When rapid attainment of serum phenytoin levels is required or in patients at high risk of adverse effects secondary to parenteral phenytoin, fosphenytoin is clearly preferred. This review will focus on the implications of the use of parenteral phenytoin products in the nonemergent setting where potential adverse effects of parenteral phenytoin may be avoided with use of established criteria for patient selection and administration.