Megaloblastic Anaemia Occurring During Treatment of Epilepsy with Phenytoin Sodium, Primidone and Phenobarbitone

Abstract

It has now been established that megaloblastic anaemia may develop in patients receiving the anti-convulsant drugs phenytoin sodium (“Epanutin”) and primidone (“Mysoline”), given alone or in combination with phenobarbitone. Hobson et al. (1956) found 16 such cases described in the literature, and reported a case of their own in which megaloblastic anaemia developed in a patient addicted to a preparation (“Tuinal”) containing equal parts of amylobarbitone sodium (“Sodium amytal”) and quinalbarbitone sodium (“Seconal Sodium”), which are closely related chemically to primidone, sodium phenytoin and phenobarbitone. Characteristically the anaemia is not related to a deficiency of nor does it respond to treatment with vitamin B₁₂, nor is there achlorhydria, thus distinguishing it from true Addisonian pernicious anaemia. The condition however responds promptly to the administration of folic acid by mouth.