Thrombocytopenia Secondary to Linezolid Administration: What Is the Risk?

tration was stopped on day 21. The WBC count and the platelet count reached nadir 4 days after discontinuation of linezolid (to cells/mL and plate3 3 3.3 10 55 10 lets/mL, respectively); the platelet count returned to a level 1 platelets/mL 3 100 10 only 7 days after administration of the drug ceased. The hemoglobin level decreased to 7.9 g/dL 7 days after linezolid therapy was stopped; there was no evidence of bleeding, but the patient required blood transfusions. The patient completed a 6-week antibiotic course with oral azithromycin; his infection was cured. These 2 cases illustrate the potential that administration of linezolid will result in serious myelosuppressive effects, necessitating serial, frequent laboratory followup and phlebotomy, as well as blood transfusions. In their report, Attassi et al. [1] focus on thrombocytopenia and emphasize that platelet counts ! plate3 100 10 lets/mL occur in 32% of patients (6 of 19 patients) with no risk factors for thrombocytopenia after 10 days of linezolid therapy, which is a far greater frequency than the product label reports [2], and report several bleeding complications. Reversible anemia recently has been reported by others as well [3]. Our cases indicate that pancytopenia may also occur in patients who are receiving linezolid. My experience, although anecdotal, is disturbing, and reading the report by Attassi et al. [1] has heightened my concern. Infectious diseases physicians are well aware that there is a great need for alternative therapeutic options for treatment of infections caused by gram-positive organisms, whether because of drug resistance, patient intolerance to first-line antibiotics, or the need for good bioavailability. However, it seems that linezolid may not be an option for prolonged treatment in a substantial number of patients and that, if it is used, close monitoring of the blood count in all patients is necessary. Linezolid is an extremely expensive drug (the cost for administration of 600 mg of the oral formulation twice daily is $100 per day); in the end, this prohibitive cost may limit indiscriminate or prolonged use, which may be a saving grace for patients.