Smoking's bad for you but a nonprofit drug safety group says a popular quit-smoking drug, Chantix, may be almost as bad, with new research linking it to problems such as heart trouble, seizures and diabetes.
The Institute for Safe Medication Practices released findings of its review of adverse-event reports filed with the FDA. The reports included 988 serious incidents linked to Chantix in the U.S. during last year's fourth quarter -- the most for any medication in that period.
Alarmed by the report, the Federal Aviation Administration banned the use of Chantix by pilots and air-traffic controllers.
Thomas Moore, the study's lead author, called on Pfizer and the FDA to "immediately" strengthen Chantix's label warnings and rigorously examine emerging safety issues.
"Based on the data available now, the existing warnings are completely inadequate," he said. "You'd expect a stop-smoking drug to have a relatively low number of reports," because it isn't used in high-risk patients.
Activists were quick to suggest the findings are the latest evidence that the U.S. Food and Drug Administration (FDA) is not adequately examining the safety of new drugs or monitoring already-approved drugs closely enough.
Sidney Wolfe, M.D., Director of the Health Research Group at Public Citizen said the Chantix findings came as no surprise to him.
"In September 2007, we warned in our publication Worst Pills, Best Pills News 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," Wolfe said.
"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," he said. "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 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.
Wolfe noted that 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, Wolfe said.
The new label 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.
Wolfe said 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," Wolfe said.
The reports reviewed by the institute in its report are available to Pfizer and the FDA and they are supposed to examine such reports closely to detect possible problems.
An FDA spokeswoman said in published reports that because of "staffing shortages," the agency was focusing on Chantix' possible psychiatric effects and claimed the warning label was accurate.
Chantix went on the market in the U.S. in 2006. Pfizer revised its labeling in November, January and last Friday to reflect concerens about its potential link to suicidal thinking.
Moore's study identified 173 injuries, including falls and traffic accidents, involving patients taking Chantix. The FDA data also contain 224 reports of potential heart-rhythm disturbances, 372 reports of possible movement disorders and 544 reports of likely glycemic problems, including diabetes.