January 2008 - Pfizer announced that it is strengthening the U.S. warnings on its smoking cessation drug Chantix (varenicline). The updated label warnings ask doctors to monitor their patients for incidences of depressed mood, agitation, suicidal thinking and suicidal behavior, which have been reported among some Chantix users. Until now, this information had been in a less prominent section of the instructions.

The updated warnings follow the FDA's announcement in November 2007 that it is conducting an Ongoing Safety Review of Pfizer's Chantix amid post-marketing reports of suicidal thoughts and aggressive and erratic behavior in patients who have taken the drug. The FDA is reviewing these cases, along with other reports of patients experiencing drowsiness that affected their ability to drive or operate machinery. A preliminary assessment reveals that many of the cases reflect new-onset of depressed mood, suicidal ideation, and changes in emotion and behavior within days to weeks of beginning Chantix treatment. Read more:  Side Effects and FDA Investigation of Chantix