Fatal aplastic anemia following chloramphenicol (chloromycetin) administration.

Reports of serious toxic effects following administration of chloramphenicol have been few. After the chemical structure of this antibiotic became established, the presence of a nitrobenzene radical caused some apprehension in regard to potential toxicity. 1 The early toxicity studies on animals 2 and man 3 led to the conclusion that chloramphenicol is of low toxicity. Later hematological observations on animals following administration of chloramphenicol by various routes were believed to reveal no deleterious effects that could be ascribed to the drug. Smith and co-workers 4 found that anemia developed following intramuscular administration of chloramphenicol to dogs in a dosage of 0.05 to 0.1 gm. per kilogram of body weight. No change occurred in the total or differential white blood cell count. Anemia did not follow oral administration. Gruhzit and associates, 5 using dogs, administered chloramphenicol by different routes for as long as four months in a dosage of 0.1 to