Methemoglobinemia and Heinz Body Hemolytic Anemia Due to Phenazopyridine Hydrochloride

Abstract

THE ability of redox drugs and chemicals to induce hemolytic anemia associated with methemoglobin and the formation of Heinz bodies in red blood cells has long been known,¹ and the mechanism of the reaction of such agents on red cells and hemoglobin has recently been described.² The purposes of this report are to record the occurrence of methemoglobinemia and Heinz-body anemia in patients taking phenazopyridine hydrochloride (phenyl-azo-diaminopyridine hydrochloride), a urinary-tract analgesic, and to describe the effects of this drug on human red cells in vitro.MethodsHematocrits, hemoglobin concentrations and reticulocyte counts were done by standard methods.³ The survival of . . .