Zyvox, the first new type of antibiotic in 35 years may help combat infections that are resistant to all known medications.
Zyvox, the novel agent kills germs that stubbornly resist even the antibiotic of last resort.
WITH CURRENT drugs losing their ability to combat
infections that can quickly spread throughout a hospital or
community, the need for new antibiotics has become critical,
experts said here Monday at a meeting of infectious disease
specialists.
While not a miracle medication, Zyvox may help fill the
void, they said. The new drug works just as well as any of the current agents and has the added benefit of overcoming drug resistance, said Dr. Harold Standiford, professor of medicine at the University of Maryland in Baltimore.
?This is a major event,? he said. ?New antibiotics are
crucially needed; think how scary resistance is.?
Drug resistance is caused by genetic mutation. And when
a mutation makes bacteria resistant to one member of a class
of antibiotics ? say, one of the many forms of penicillin ? italso develops cross-resistance to all the other forms of
penicillin.
Unlike current antibiotics, Zyvox blocks bacterial growth
by disrupting initiation of the process the microbe uses to
make proteins, Standiford said. ?And if bacteria can?t make
proteins, they die. ?Current antibiotics sabotage the process once it is underway, while Zyvox prevents it from starting,? he said.
This totally different mechanism of action than any other
antibiotic is what makes Zyvox so exciting, he said.
?A new mechanism of action means there is a much
higher chance that we will not see cross-resistance with other drugs,? said Dr. Donald Batts, director of infectious diseases clinical development at Pharmacia & Upjohn, manufacturer of Zyvox.
The drug has been studied against every other class of
antibiotic without sign of cross-resistance, he noted.
?This might be able to bail us out if a hospital has a
situation where a drug-resistant strain is spreading and killing patients,? Batts said.
Another advantage is that Zyvox can be administered
either intravenously or in tablet form, Standiford said.
Known scientifically as linezolid, Zyvox is the first of the
class of drugs known as oxazolidinones. Pharmacia &
Upjohn plans to submit the study data to the Food and Drug
Administration for approval by the end of the year, according to Standiford.
Just last week, Americans received another
much-needed weapon in the battle against deadly
drug-resistant bacteria, with the Food and Drug
Administration approving a new antibiotic known as
Synercid. But unlike Zyvox, Synercid works similarly to other antibiotics already on the market. Also, it has been used in Europe in animal feed for years.
Since genetic mutation to bacteria quickly evolve,
doctors fear that Synercid resistance will appear soon, too.
In contrast, Zyvox is a totally synthetic compound
designed from scratch that attacks the microbe in a
completely different way, said Dr. George Eliopoulos of
Harvard Medical School. ?Therefore we think resistance will
be slow to emerge once we start using it clinically.?
THE STUDIES
Zyvox works against so-called gram-positive bacteria,
which account for more than half of infections treated in
hospitals. Among them: staph, strep and enterococci bacteria.
They cause ailments ranging from abscesses and boils to
pneumonia and urinary tract infections.
To date, the drug has been studied in more than 5,000
patients, ranging in age from 1 to 80. Among the findings:
In 526 patients with community-acquired pneumonia,
Zyvox eradicated the bacteria in 91 percent, compared with
89 percent of patients given the gold standard antibiotic
therapy of IV ceftriaxone followed by oral cefpodoxime.
In a study of 397 patients with hospital-acquired
pneumonia, Zyvox plus aztreonam helped 66 percent,
compared with a 68 percent success rate in those given
vancomycin plus aztreonam.
Similar results were seen in studies in patients with boils,
abscesses and other skin infections. And in patients with
resistance to methicillin or vancomycin, Zyvox worked in 77
Nevertheless, even while doctors here said they
welcomed the introduction of Zyvox, Eliopoulos said that he
doubts any antibiotic can ever totally combat the resistance
problem. ?We can slow it down, but frankly, I don?t know if
we can ever beat it,? he said.
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