Drug Interaction Report

MONITOR: Chloramphenicol can cause bone marrow depression and inhibit red blood cell maturation, which may interfere with the therapeutic effects of iron or vitamin B12 in the treatment of anemia. In a group of 22 patients receiving iron dextran for iron deficiency anemia, 10 patients who also received chloramphenicol had inadequate hematologic response to the iron therapy. Four patients receiving vitamin B12 for pernicious anemia were also unresponsive to the B12 therapy while being treated with chloramphenicol. Reversible bone marrow depression is more likely to occur at higher chloramphenicol dosages that produce serum levels of 25 mcg/mL or greater.

MANAGEMENT: Patients with preexisting anemia should preferably not receive chloramphenicol due to the drug's depressive effect on bone marrow and reticulocytes. If use is unavoidable, the lowest effective dosage of chloramphenicol should be given. Hematologic response to iron or vitamin B12 therapy should be closely monitored.