A critical review of fosphenytoin sodium injection for the treatment of status epilepticus in adults and children

Introduction Status epilepticus (SE) is a neurological emergency that can occur in patients with or without epilepsy. Rapid treatment is paramount to mitigate risks of neuronal injury, morbidity/mortality, and healthcare-cost burdens associated with SE. Fosphenytoin is the prodrug of phenytoin designed to enable faster administration and improved tolerability as compared to intravenous (IV) phenytoin in the treatment of SE. Areas covered This review evaluates the chemistry, pharmacokinetics, pharmacodynamics, safety, and tolerability of fosphenytoin. Efficacy data for fosphenytoin in the treatment of SE in adults and children are analyzed from initial phase I trials in 1988 through current phase III trials, including the Established Status Epilepticus Treatment Trial (ESETT). Expert opinion IV phenytoin is an established treatment of SE, but its alkaline aqueous vehicle is associated with dermatologic irritation and systemic complications when rapidly infused. The water-soluble nature of its prodrug, fosphenytoin, allows for rapid infusion, and it is rapidly converted to phenytoin when administered intravenously or intramuscularly. In the ESETT, IV fosphenytoin demonstrated similar efficacy in treatment of established SE when compared to IV levetiracetam and IV valproate in adults and children, making it a reasonable choice in the treatment of SE that is unresponsive to benzodiazepines.