Over the past several months concerns involving the
prescription smoking cessation medication Chantix have been mounting. In the
last quarter of 2007 the FDA received nearly 1000 reports of adverse events,
more than any other drug, associated with Chantix. Today ABC News reported that when
one of the nation’s top anti-smoking researchers, Dr. John Spangler, expressed
his concerns over a year ago about possible adverse effects linked to prolonged
use of the drug, both U.S. regulators and Pfizer brushed his thoughts aside.
New studies now suggest that Spangler was ahead of the game with his questions
about the safety of Chantix.
Earlier this year the FDA revised the label of Chantix to
include warnings that the drug may have links to depression, nueropsychiatric events, and suicidal behavior, and last month a non profit organization
released the results of a study that linked Chantix to metal confusion, lapses
in alertness, dizziness, muscle spasms and loss of consciousness. This prompted
the FAA to remove Chantix from the list of drugs that pilots and air traffic
controllers are allowed to take. Days later the drug was removed from the list of
acceptable medications for truck drivers.
Spangler says the safety study by researchers employed by
Pfizer and published in a relatively obscure medical journal looked at far too
few subjects — a total of only 251 taking the drug — to determine whether or
not the drug is safe when used over that duration.
Yet, the conclusion of the study reads, “Varenicline 1
mg BID can be safely administered for up to 1 year” — a conclusion,
Spangler says, that is not supported by the data.
Spangler also claims that the authors of the study also
failed to mention that patients taking Chantix were two and half times more
likely to experience serious adverse events.
While Pfizer maintains that the drug is safe to take for a
one-year period, Chantix is designed to be taken for a maximum of 24 weeks.
We are just past the two-year mark for the approval ofChantix. It will be interesting to see what happens from this point out. Most
experts say that we do know the true effects of a drug until seven years after
approval, but with two label changes and thousands of adverse events reported
we could be well on our way with Chantix.