Study Suggests That Higher Chance Of Death Is Related To The Type Of Organism Causing A Patient’s Infection

(Posted by Tom Lamb at DrugInjuryWatch.com)

On March 16, 2007 the FDA issued a safety alert about the antibiotic Zyvox, also known as linezolid.  This FDA Alert is based on findings from an open-label, randomized drug study which compared Pfizer Inc.’s Zyvox to vancomycin, oxacillin, or dicloxacillin, three generic antibiotics.

In more detail, this Pfizer-sponsored study compared Zyvox to the three other generic antibiotics in patients with bloodstream infections related to catheters.  This use of Zyvox is not currently approved by the FDA, and therefore would be considered an "off-label" use of Zyvox.  At present, Zyvox is approved by the FDA for the treatment of various bacterial infections.

As background, bacteria can be either gram-negative or gram-positive depending on their type of outer membrane. The types of infections for which Zyvox use has been approved by the FDA are gram-positive.

According to the FDA, the chance of death for Zyvox patients was related to the type of organism causing the infection:

Patients with Gram positive infections had no difference in mortality according to their antibiotic treatment.  In contrast, mortality was higher in patients treated with [Zyvox] who were infected with Gram negative organisms alone, with both Gram positive and Gram negative organisms, or who had no infection when they entered the study.   

It is unclear what Pfizer had hoped to establish by means of this Zyvox study as, according to a March 16, 2007 Reuters article by Susan Heavey, a Pfizer representative said that the drug company would not seek FDA approval for any use of Zyvox in patients with catheter-related infections:

"We don’t have plans at this point in time to file for this indication," Dr. Mark Kunkel, head of Pfizer’s anti-infective division, told Reuters.

Results from the study have not yet been made public, but will be presented at upcoming meetings and may be published, Kunkel said. He added the findings met their main goal of curing infection within 7 to 14 days.

The FDA is currently reviewing the results of this Pfizer drug study as well as other available information about Zyvox.  In the meanwhile, the FDA advises doctors not to use Zyvox if they suspect an infection in caused by gram-negative bacteria.