Toxicity of Primaquine in Negroes

Hemolytic reactions during antimalarial therapy have proved to be a limiting factor in the use of 8-aminoquinolines for the cure of vivax malaria. The most severe type of reaction is clinically identical to blackwater fever, and is characterized by massive, explosive, intravascular hemolysis with hemoglobinemia and hemoglobinuria, which constitutes a medical emergency necessitating immediate transfusions. Acute hemolysis has been observed during the therapeutic use of a number of 8-aminoquinolines, for example, pamaquine, 1 pentaquine, 2 and isopentaquine. 3 The incidence of hemolytic reactions is higher in the dark-skinned races. According to Earle and co-workers, 1 5 to 10% of Negroes contract acute hemolysis when given 30 mg. or more of pamaquine daily. Only 1% of white subjects studied by him contracted hemolysis which, however, was not acute. PROCEDURES Dosage Schedules.— Primaquine 4 8-(4-amino-1-methylbutylamino)-6-methoxy quinoline, 30 mg. of base daily, was administered orally in single or divided doses to 110 normal