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Myelosuppression Reported During Linezolid Therapy

Cheryl A. Thompson

Low white-blood-cell counts and similar signs of reduced bone marrow activity have been reported in patients receiving the antimicrobial linezolid, according to a "Dear Health Care Professional" letter (PDF) from the manufacturer. 

Pharmacia Corp., in the letter posted Friday on the Food and Drug Administration (FDA) Web site, advised clinicians to monitor patients' complete blood count every week during linezolid therapy and consider discontinuing treatment if myelosuppression develops or worsens. Labeling (PDF) for the drug product, Zyvox, now includes a warning about myelosuppression.

An unstated number of cases of linezolid-associated myelosuppression have been reported to the company and FDA since marketing of the drug in April 2000. The postmarketing reports indicate that the depressed blood-cell type increases in number, but does not reach its pretreatment level, after linezolid therapy stops, the company stated.

New cases of myelosuppression during linezolid therapy should be reported to Pharmacia (800-253-8600 ext. 38244) or FDA's Medwatch program (800-FDA-1088).

Linezolid is indicated for treatment of adults with an infection caused by vancomycin-resistant Enterococcus faecium or with nosocomial pneumonia, a skin or skin structure infection, or community-acquired pneumonia.