|
Pollen pill coming soon
Shots
aren't the only option for immunotherapy. In fact,
patients may much prefer the pill version of the
treatment, now available in Europe. Grazax, developed
by Danish company ALK-Abelló and approved
in some 27 European countries, contains extracts
from timothy grass and has been shown to be effective
against all forms of grass pollen allergies that
exist in Europe. Taken eight weeks before hayfever
season starts, Grazax has outperformed antihistamines
by 30% in trials. In addition, 82% of subjects
said it significantly improved their quality of
life.
Grazax
recently got the green light for Phase III trials
here. Earlier this month, ALK-Abelló inked
a deal with Schering-Plough to manufacture and
distribute the pills in North America. The authors
of the current Cochrane study are working on future
literature reviews comparing different delivery
systems.
|
Since she was a small girl, 37-year-old
Patty H has suffered from hayfever. One of her earliest
memories is of her mother chasing her with a box of
tissues, chiding her to "Blow your nose, Patty!" Every
year during pollen season she's a swollen-eyed, runny-nosed
wreck. She's asked her family doc about allergy shots,
but he wasn't keen, telling her they're really only
for the severest cases and that he was worried because
he'd read about some fatalities.
It turns out Patty's doctor's caution,
though well-intentioned, may have been misplaced. Injecting
patients with the allergens that cause hayfever is safe
and effective for most patients, according to a new
review published online in the Cochrane Database
of Systematic Reviews on January 24.
GROWING
PROBLEM
While not life-threatening on its own, the scope of
the hayfever problem is huge. Incidence has been on
the rise for the last two decades, especially in developed
countries: as many as 30% of adults and 40% of children
living in the developed world now suffer from allergic
rhinitis. It's a serious quality of life issue for many
of them.
Immunotherapy injections have been
around for years, but fears about severe adverse events
and even deaths had prompted restrictions on how they
could be administered, which led to a decline in their
use. Because the immunotherapy approach was also thought
to be less effective than other treatments, it simply
wasn't worth taking any chances.
The authors of the current review,
led by Dr Moises Calderon of Royal Brompton Hospital
in London, decided to take a serious look at whether
the risks were as severe as feared and whether immunotherapy
is any less effective than, say, antihistamines.
BETTER
THAN EXPECTED
The reviewers chose 51 randomized controlled trials
— none of which involved children exclusively —
with a total 2,871 subjects from over 1,100 potential
immunotherapy studies.
Those selected looked at immunotherapy
shots for patients with tree, grass and weed pollen
allergies, with each patient receiving an average of
18 injections over a period of three days to three years.
Different reporting methods made it difficult to determine
the best dose for optimal maintenance, but high doses
of between 5-20mcg of major allergen per shot for each
of the patient's primary allergens seem to work best.
Patients in the studies reported
significant quality of life improvement in terms of
runny nose, watery eyes and other common symptoms. They
were also able to reduce their dependence on allergy
meds.
The treatment's mechanism isn't
absolutely certain, but "the most plausible explanation,"
write the authors, "is that immunotherapy modifies the
immune response by producing less of the 'harmful' antibodies
(specifically immunoglobulin (Ig) E) and more of the
'protective' antibodies called IgG."
ADVERSE
EVENTS
Serious adverse events were reported in four cases.
Three occurred in treatment groups — two cases
of anaphylaxis and one case of exacerbated asthma with
edema of glottis and hypotension — and one case
of anaphylaxis in a placebo group. All four patients
fully recovered and remained enrolled in the studies.
Information on the clinical status
of the patients who suffered bad reactions wasn't available.
But the authors note that previous reports of adverse
events or fatalities, "occurred almost exclusively in
patients with co-existing asthma.... Furthermore, asthma
was frequently poorly controlled."
Between 13% and 38% of allergic
rhinitis patients also suffer from asthma. The authors
point out many of the patients who died also had other
risk factors, including diabetes and coronary vascular
disease. They add that poor adherence to immunotherapy
guidelines, dosing mistakes and delay or failure to
administer adrenaline all likely contributed to the
deaths.
"Because of the very low, but real,
risk of an adverse reaction, this treatment should only
be given in facilities that have full resuscitation
back up," concluded Dr Calderon. "Unfortunately, in
the UK, this means that it can only be given in specialized
centres, which greatly limits its use."
All things considered, the authors
conclude that immunotherapy shots work well to relieve
seasonal allergies, especially in patients whose symptoms
aren't well controlled with medication. The study didn't
determine whether it could also be a safe option for
asthma patients.
Cost was another concern they didn't
look at. However, an April 2000 study in Respiratory
Review concluded that since most antihistamines are
now available over the counter and no longer covered
by drug plans, shots are comparatively more cost effective
— $1,200 US, while immunotherapy rings in at about
$800 US the first year. After that, when the maintenance
jabs are required less often, the cost drops to $290
to $170 US.
|
