Isopto Fenicol and Bone marrow suppression

Chloramphenicol may cause bone marrow depression and other hematologic toxicities, which can be irreversible or reversible. The former type is independent of dose and results in aplastic anemia with a high rate of mortality, generally from hemorrhage or infection. It has been reported following both systemic and topical administration of chloramphenicol and has an estimated incidence of 1 in 25,000 to 1 in 40,000 courses of therapy. Bone marrow aplasia or hypoplasia may occur after a single dose but more often develops weeks or months after the drug has been discontinued. A reversible myelosuppression occurs much more frequently and is characterized by anemia, vacuolation of red blood cells, decreased reticulocyte count, leukopenia, thrombocytopenia, increased serum iron concentrations, and increased serum iron-binding capacity. It is dose-dependent, occurring regularly at chloramphenicol dosages exceeding 4 g/day (in adults) or at plasma drug concentrations >= 25 mcg/mL, and usually responds to withdrawal of the drug. Therapy with chloramphenicol should be administered cautiously, if at all, in patients with preexisting blood dyscrasias and/or bone marrow depression. Complete blood counts and differential reticulocyte counts should be performed in all patients prior to initiating therapy and approximately every 2 days during therapy. Marked depression of blood counts and/or development of other hematologic abnormalities may be indication for withdrawal of chloramphenicol therapy.