Introduction: Fosphenytoin, a water-soluble phenytoin prodrug, is given intravenously to administer phenytoin possibly more safely than intravenous administration of phenytoin.
Case Report: A 71-year-old female was admitted to our hospital’s emergency department with head trauma. She had a history of seizures that were incompletely controlled with carbamazepine. She suffered a tonic-clonic epileptic seizure in the intensive care unit and fosphenytoin was intravenously administered. After approximately three minutes of the intravenous drip-infusion, she developed sudden bradycardia followed by cardiac arrest. The patient required cardiopulmonary resuscitation and intratracheal intubation for five minutes before becoming hemodynamically stable. Mechanisms of electrocardiogram alteration by fosphenytoin were discussed.
Conclusion: Clinicians should be more aware of the association of fosphenytoin with adverse cardiac events. Baseline electrogram should be obtained for all patients receiving fosphenytoin to identify underlying cardiac problems.

Keywords: Adverse effect, Cardiac arrest, Fosphenytoin