FDA on Thursday is expected to issue an advisory that urges
physicians to conduct genetic testing before prescribing
GlaxoSmithKline's antiretroviral drug abacavir to reduce
allergic reactions in people taking the drug, the New
York Times reports. The recommendation to conduct genetic
screenings will be included in a black box warning on
the drug's label.
HIV-positive people who have a certain variation in an
immune system gene should not take abacavir because they
have a higher risk of a severe allergic reaction to the
drug, according to FDA. A GSK-sponsored study, published
in the New England Journal of Medicine in February, found
that genetic screening prior to prescribing abacavir could
reduce the incidence of suspected hypersensitivity reactions
from 7.8% to 3.4%. Symptoms of the reaction include fever,
rash, nausea and breathing difficulties. Based on the data,
it was estimated that about 61% of people with the genetic
variant could experience a severe allergic reaction to
abacavir, compared with 4% of people without the variant.
In addition, abacavir's revised label will mention a study
that found an increased incidence of heart attacks among
people taking the drug, the Times reports. The label also
will mention that GSK conducted its own review by pooling
the results of numerous clinical trials and found no increased
risk of heart attack. The new label will say that although
the data on the increased risk of heart attack is "inconclusive," doctors
still should be cautious in prescribing the drug (Pollack,
New York Times, 7/24).
Reprinted with kind permission from http://www.kaisernetwork.org.
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