Late 1990s-2005

— Clinical trials are conducted on Chantix, a Pfizer Inc. drug intended to help smokers quit. Although people with mental illnesses make up a disproportionate number of smokers, they are excluded from trials of the drug, known generically as varenicline.


May: The Food and Drug Administration medical officer conducting a safety review of Chantix, Dr. Howard Josefberg, submits a report endorsing the approval of Chantix — despite finding that Pfizer’s studies may have been “too carefully screened” because they excluded smokers with mental illnesses. Two days later, the FDA approves the sale of Chantix after a speeded-up review. No request is made by the agency for follow-up studies on mentally ill smokers.

— Chantix sales for the year: $101 million.


March: Article by Pfizer researchers lauding Chantix for long-term use appears in the journal Current Medical Research and Opinion.

November: FDA discloses for the first time, in an “early communication warning,” that it has received reports of suicide attempts from patients taking Chantix.

— Sales for the year: $883 million.


January: FDA orders revised labeling indicating that Chantix’s safety for mentally ill patients has not been established.

February: FDA issues public health advisory on Chantix, saying “it appears increasingly likely that there may be an association between Chantix and serious neuropsychiatric symptoms.”

May: FDA tells Pfizer in a letter that, based on new safety information, the company will be required to conduct “postmarketing” research “to assess the known serious risk of neuropsychiatric symptoms, including changes in behavior, agitation, depressed mood, and suicidal thoughts or actions.” The agency says it will provide more specifics later. Separately, the  Federal Aviation Administration bans pilots and air traffic controllers from using Chantix.

— Sales for the year: $846 million.


June: FDA specifies new postmarketing research. Pfizer is told to conduct a study to “determine whether individuals with prior history of psychiatric disorders are at greater risk for development of clinically significant neuropsychiatric events.”

July: FDA orders Pfizer and the makers of a competing product, Zyban, to put “black box warnings” on their packaging. The intent is to call attention to the medications’ serious or life-threatening risks. The FDA notes that it has received close to 5,000 reports of serious psychiatric events.

— Sales for the year: $700 million.


— Reports of serious side effects continue to stream in. The nonprofit group Institute for Safe Medication Practices identifies more than 300 reports of serious adverse events, in January through March, believed related to the drug.

— The number of lawsuits over Chantix filed in federal court reaches more than 1,000, with plaintiffs alleging the drug led to suicides, attempted suicides and other side effects.

— Sales for the first three quarters of the year: $522 million.