Taking a new class of antibiotic
after an asthma attack can relieve symptoms, according
to new research that suggests atypical bacteria may
play a role in the disease's exacerbations.
A study in the April 13 edition
of the New England Journal of Medicine reports
that patients who took the antibiotic telithromycin
reported fewer symptoms following an asthma attack than
those who took placebo. Telithromycin belongs to a new
class of antibiotics, ketolides, which can reduce inflammation
and act against atypical bacteria like Chlamydophila
pneumoniae and Mycoplasma pneumoniae.
Professor Sebastian Johnston from
Imperial College London, who led the research, said:
"Traditionally antibiotics have not proven effective
in treating asthma attacks, but this development could
open up a whole new area of research in the treatment
of asthma."
A total of 278 adults aged 18-55
from more than 70 centres around the world took part
in the trial. All of the subjects were enrolled within
24 hours of an acute exacerbation that required medical
care.
Half were randomized to receive
the antibiotic telithromycin at 800mg daily for 10 days.
The rest were given a placebo. The trial was double-blinded,
and patients continued to take their normal asthma medications
such as albuterol or levalbuterol hydrochloride.
BREATHING
EASIER
The improvements seen in symptoms were significant,
if not very dramatic. On a seven-point symptom scale,
the treatment group saw an average improvement of 1.3
points, compared to 0.8 points in the placebo group.
Time to recovery averaged five days in the treated patients,
and eight in the others.
There was no difference in the
other primary outcome, morning peak expiratory flow.
But over the first 14 days, treatment group patients
experienced nearly double the improvement from baseline
in terms of forced expiratory volume. This treatment
advantage then subsided, leaving the two groups equal
after 42 days.
GIV'R
TO THE LIVER?
The most common side effects seen in the telithromycin
group were diarrhea, nausea and upper abdominal pain,
affecting 10%, 5% and 3% of patients respectively. Only
nausea was significantly more common in the treatment
group than in the placebo group.
A report in the March 21 issue
Annals of Internal Medicine described three cases
of severe liver toxicity seen in patients taking telithromycin,
but no such cases emerged in this small trial.
Most antibiotics used for respiratory
tract infections have been associated with hepatotoxicity
at one point or another. While the FDA is keeping an
eye on telithromycin, there seems no reason to believe
it is more dangerous than others. Some 22 million courses
of treatment with the drug have been prescribed for
sinusitis, acute bronchitis and pneumonia since 2001.
A study comparing it to amoxicillin-clavulanate in over
24,000 patients found no significant difference between
the two treatments in liver toxicity.
Patients with overt respiratory
infections were excluded from the trial, but that doesn't
mean infection isn't involved in their symptoms. It's
already widely accepted that viral infection is often
the cause of asthma exacerbations.
The trial's basic hypothesis was
that Chlamydophila pneumoniae and Mycoplasma
pneumoniae are also implicated in asthma symptoms,
thus the trial's name: TELICAST, short for telithromycin,
chlamydophila and asthma.
CURIOUS
FINDINGS
When tested for these two bacteria, 61% of the study's
participants were serologically positive. Yet oddly,
there was no correlation between the patients' measured
bacteriologic status and their response to the antibiotic.
This leaves open the question of
whether the drug is working through another mechanism,
since the ketolide antibiotics also have immunomodulatory
qualities -- that is, they have the capacity to modify
immune functions -- and they can reduce inflammation.
"Although we're not sure about
the exact mechanism which caused this antibiotic to
be effective, this study indicates it does clearly have
a beneficial effect," said Professor Johnston. "We still
need further trials to confirm these results, to investigate
the mechanisms of action of this treatment, to see if
the same benefits are seen with other related antibiotics
and to see which patients are most likely to benefit."
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