Anticonvulsant-Associated Megaloblastic Anemia

Abstract

IN 1954 Badenoch¹ reported "a hitherto undescribed form of megaloblastic anemia" in 2 patients who were receiving phenytoin (diphenylhydantoin) and phenobarbitone (phenobarbital). This association was subsequently confirmed by others.^{2 3 4 5 6 7 8} Megaloblastic anemia has followed diphenylhydantoin therapy alone^{9 , 10} and phenobarbital alone.^{11 , 12} In addition, the use of related drugs has been implicated in the production of megaloblastosis. These include primidone,^{13 14 15} methophenobarbital,¹⁶ secobarbital combined with amobarbital¹⁷ and other combinations of anticonvulsants.^{18 , 19} An excellent hematologic response to large doses of folic acid has occurred in most cases.^{2 , 3 , 5 , 6 , 10 11 12 13 , 17 18 19} However, as little as 500 microgm. daily has produced remission.²⁰ The present case is reported for the following . . .