QuarterWatch™ Reports May 2008

Strong Safety Signal Seen for Chantix (Varenicline)

In this issue of QuarterWatch™ we examine a strong signal of multiple safety problems with Chantix (varenicline), a drug to help people stop smoking.

Varenicline is suspected in various adverse drug event reports of causing a wide spectrum of injuries, including serious accidents and falls, potentially lethal cardiac rhythm disturbances, severe skin reactions, acute myocardial infarction, seizures, diabetes, psychosis, aggression and suicide. The cases were analyzed and classified using computerized excerpts of adverse event reports which the FDA publishes for research use.

The FDA approved varenicline in May 2006 after granting it a priority review. Varenicline is a partial agonist of one of the nicotinic acetylcholine receptors in the brain and nervous system,1 and currently the only marketed and approved drug with this mechanism of action.

In the 4th quarter of 2007 varenicline accounted for 988 serious injuries in the U.S. reported to the FDA, more than any other individual drug in this time period. By comparison the FDA received a median of 5 reports of serious injury for 769 different drugs in the 4th quarter. Only 35 drugs accounted for 100 or more reports. This large volume of reports prompted us to conduct an analysis of all adverse events for varenicline since marketing approval in 2006.

The FDA has recently issued a Public Health Advisory about one of the most marked adverse effects of varenicline, psychiatric symptoms that included “changes in behavior, agitation, suicidal ideation, attempted and completed suicide.” 2 However, the FDA alert provided no information about the numbers of reported neuropsychiatric events among treated smokers.


References

  1. Prescribing Information for Chantix (varenicline) Tablets. Pfizer Inc.; January, 2008.
  2. U.S. Food and Drug Administration. Public Health Advisory: Important Information on Chantix (varenicline). U S Food and Drug Administration, Center for Drug Evaluation and Research. February 1,2008.

QuarterWatch™ is an independent publication of the Institute for Safe Medication Practices (ISMP). We analyze computer excerpts from the US Food and Drug Administration (FDA) Adverse Event Reporting System (FAERS). These reports (best known as MedWatch reports) are a cornerstone of the nation’s system for monitoring the safety of prescription drugs after FDA marketing approval.