Clinical impact review Fosphenytoin for the treatment of status epilepticus: an evidence-based assessment of its clinical and economic outcomes Andrew Thomson Core Medical Publishing, Knutsford, UK Abstract Introduction: Status epilepticus (SE) is a life-threatening condition requiring prompt treatment in the emergency department to control seizures and limit potential neurologic damage. Fosphenytoin is a water-soluble prodrug of phenytoin (an established treatment option for SE) that has been developed to overcome the often severe venous adverse events that can occur following the intravenous administration of phenytoin. Aims: The objective of this article is to review the evidence for the use of fosphenytoin in the treatment of SE. Evidence review: Fosphenytoin can be infused more rapidly than phenytoin and there is evidence that therapeutic drug levels are achieved at least at a similar rate. Although few studies have been conducted in SE patients, there is evidence that fosphenytoin is at least as effective as phenytoin in terms of response and control of SE. There is also moderate evidence that there are fewer vascular adverse events following intravenous fosphenytoin compared with phenytoin administration when both drugs are infused at the recommended dosage and rate. Evidence from pharmacoeconomic studies indicates that a reduction in the incidence of adverse events and their subsequent management are critical factors for cost-effectiveness with fosphenytoin. Clinical value: In conclusion, fosphenytoin is a valuable treatment option for the rapid treatment of SE; the risk of venous adverse events is lower than with phenytoin when administered at the recommended rate. Key words: fosphenytoin, status epilepticus (SE), treatment, evidence, outcomes Core evidence clinical impact summary for fosphenytoin in status epilepticus Moderate Cost-effectiveness reliant upon reduced incidence of adverse events Outcome measure Patient-oriented evidence Reduction in adverse events More rapid discharge from emergency department Use in children and elderly, and other patient groups with poor peripheral vascular access Disease-oriented evidence Seizure control Economic evidence Cost-effectiveness More rapid achievement of therapeutic blood levels Moderate More rapid infusion rate Evidence Implications Moderate Limited Limited Moderate Has advantages with improved tolerability compared with intravenous phenytoin. Faster rate of administration with fosphenytoin compared with phenytoin. Improved tolerability contributes to cost-effectiveness Further studies required Further studies required Effective treatment but more rapid control of status epilepticus seizures with fosphenytoin has not been demonstrated