Linezolid, which goes by the brand name Zyvox, is the first in a new class of synthetic drugs called oxazolidinones to be approved for use in the United States. The drug, which won the nod from the U.S. Food and Drug Administration in 2000, works by stopping bacterial growth.
In one study, Richard Wunderink compared the use of linezolid with vancomycin (Vancocin), the traditional antibiotic of last resort, in patients with a form of hospital-acquired pneumonia called MRSA, for methicillin-resistant Staphylococcus aureus.
Up to 100,000 persons are hospitalized each year with MRSA infections, according to Wunderink, citing CDC statistics. This type of pneumonia typically develops in hospitalized patients who are elderly or very sick, but also it also occurs in nursing home patients admitted to the hospital.
In Wunderink's study, those getting linezolid were twice as likely to survive as those on vancomycin. The drugs were given intravenously every 12 hours for seven to 21 days.
"MRSA is the cause of up to 30 percent of hospital-acquired pneumonias," says Wunderink, a physician at Methodist Health Care Memphis and a clinical associate professor of medicine at the University of Tennessee in Memphis.
He predicts linezolid will begin to be used more with the news of a survival difference, although he points out that linezolid is much more expensive. "It's at least 50 percent more than vancomycin," he says. Pharmacia, manufacturer of Zyvox, funded the study.
In another study, linezolid proved promising for multi-drug resistant tuberculosis treatment. Dr. Nicos Hadjiangelis and his colleagues from the New York School of Medicine/Bellevue Chest Service in New York City reported it was well tolerated and safe for a small group of five patients, all diagnosed with what doctors call multi-drug resistant tuberculosis.
Tuberculosis, a bacterial infection that typically attacks the lungs, can also affect other organs. In 2001, 15,898 new cases of TB were reported n the United States, according to the American Lung Association.
Multi-drug resistant TB, defined as a strain resistant to treatment by two commonly used drugs, isoniazid and rifampin, is a major health problem worldwide.
When the researchers added linezolid to other drugs that weren't working well enough, the sputum cultures in all five turned negative for TB. "It means the treatment is effective," Hadjiangelis says.
Another expert says that while the pneumonia study is "not very newsworthy," the TB study is "of interest for several reasons." Multi-drug resistant tuberculosis occurs all over the world, says Dr. David N. Gilbert, a physician at Providence-Portland Medical Center in Oregon and immediate past president of the Infectious Diseases Society of America. While scientists know linezolid appears to work in the laboratory test tube, "it's nice to get some clinical data," he says.
But he does think giving all the credit to the linezolid for the TB patients may be overstatement. "With the combination of drugs used, it's difficult to say linezolid did it. It may have contributed."
What is needed next, he says, is a controlled study of linezolid in an area where the drug-resistant TB is a problem.
The presentations were made recently at the 99th International Conference of the American Thoracic Society in Seattle.