Increased Clearance of Phenytoin during Infectious Mononucleosis

HIPPOCRATES observed that epileptic patients had fewer seizures during febrile illnesses, and data gathered during epidemics of measles and typhoid in patients institutionalized at Bicêtre and Salpêtrière supported his conclusion.¹ Since the development of effective antiepileptic drugs, this pat-ern has changed.^{2 3 4} We investigated an epileptic patient who had more frequent seizures during infectious mononucleosis. Low phenytoin concentrations from increased drug clearance were observed, suggesting that altered drug kinetics may precipitate seizures during illnesses. Case Report A 22-year-old woman with partial complex seizures was admitted to the University of Minnesota Epilepsy Unit for treatment. She weighed 64 kg and was 172.