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New Study Highlights Dangers of Anti-Smoking Drug Chantix

May 21, 2008  

New Study Highlights Dangers of Anti-Smoking Drug Chantix

Statement of Sidney Wolfe, M.D., Director of the Health Research Group at Public Citizen

The large number of adverse reactions in the careful study being published today by the Institute for Safe Medication Practices (ISMP) adds new urgency to our previous safety concerns about Chantix. It also highlights the dangerous inadequacy of the response of Pfizer and the Food and Drug Administration (FDA) to the rapidly increasing number of serious, life-threatening adverse events seen with this drug.

In September 2007, we warned in our publication Worst Pills, Best Pills News (online at WorstPills.org) that people should not use Chantix until 2014 because of the inadequate amount of information about its safety and concerns raised by the increased amount of psychiatric adverse events that occurred in the randomized trials preceding its approval.

In one of the studies, 6.8 percent of patients using Chantix had psychiatric adverse events as opposed to only 2.4 percent of those given a placebo.

In the just-released May 2008 issue of the British Drug and Therapeutics Bulletin (DTB), the authors stated that: “We are concerned about reports of psychiatric problems with this drug. Given such concerns, marketing claims of a ‘favourable safety and tolerability Profile’ are questionable.”

The ISMP study of 173 serious reports of accidents and injuries, including 28 road traffic accidents, calls for a much stronger warning than in the recently revised new labeling and new patient medication guide for the drug (revised May 16). The new label inadequately states that “[p]atients should be advised to use caution driving or operating machinery until they know how quitting smoking with Chantix may affect them.” The inadequacy of this “use caution” warning is further emphasized by the statement in the label that there were, in clinical trials with Chantix, “Frequent: Disturbance in attention, Dizziness, Sensory disturbance.” None of these are compatible with safely driving (cars, buses, trains or planes) or operating machinery. Instead, we agree with the advice this week in the DTB that “Patients taking varenicline should, therefore, be advised not to drive or operate machinery [emphasis added] until they know whether the drug will impair their ability to do so.”

In addition to the warning against driving, we also urge that the FDA:

  • require a black box warning about the adverse effects including warning against driving as discussed above, the adverse psychiatric effects such as suicidal thoughts or actions, depression and agitation and serious adverse skin reactions;
  • require Pfizer to immediately send a dear doctor letter warning about these adverse effects;
  •    require Pfizer to significantly strengthen the warning language in the label and patient medication guide.