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Study Finds Similar Safety, Efficacy for Linezolid and Vancomycin

Kate Traynor

An international study suggests that linezolid is as safe and effective as vancomycin for the treatment of methicillin-resistant Staphylococcus aureus (MRSA) infection.

According to a report in the June 1 issue of Clinical Infectious Diseases, 73 percent of 108 patients who received either linezolid or vancomycin to treat a confirmed MRSA infection had no clinical symptoms of infection 15–21 days after therapy ended. Microbiological testing of samples from 113 patients with confirmed MRSA showed that treatment had cleared the infection for 59 percent of the linezolid users and 63 percent of the patients who received vancomycin.

A safety analysis of data from 460 study participants who had received at least one dose of linezolid or vancomycin found no difference in the frequency of severe adverse events between the treatment groups. Patients who received linezolid were, however, more likely than those who used vancomycin to suffer from diarrhea. In all, 11 percent of the 240 patients who received linezolid and 4 percent of the 220 vancomycin users reported having diarrhea during the study.

The randomized, open-label trial, which was funded by linezolid (Zyvox) manufacturer Pharmacia Corp., involved hospitalized and institutionalized patients at 104 sites in North America, Europe, Latin America, and Asia. Study participants were at least 13 years old and had a presumed MRSA infection of the blood, lungs, urinary tract, skin, or soft tissues.

Patients in the vancomycin group received 1,000 mg of the drug intravenously twice daily. People in the linezolid group were initially given a 600-mg intravenous dose of the drug twice daily, but patients whose symptoms improved could be switched to linezolid oral tablets, 600 mg twice daily. Sixty-one percent of the patients in the linezolid group were switched to the oral formulation during the course of treatment.

Of the 460 patients who enrolled in the study, 70 discontinued therapy because they were found not to be infected with MRSA. Seven percent of the patients in the linezolid group and 6 percent of those who received vancomycin died during the study. Overall, 33 percent of linezolid users and 31 percent of patients in the vancomycin group did not complete their assigned treatment.

Thirty percent of the linezolid users and 19 percent of the patients in the vancomycin group were discharged from the hospital during the first week of treatment. The research team speculated that patients who are switched to oral linezolid may leave the hospital sooner than patients who receive intravenous therapy throughout their hospital stay—a trend that could produce "potentially significant economic benefits."