Both drugs now will carry "black box" labels warning that people taking the drugs should be closely watched for signs of suicidal thoughts, depression, hostility, or other changes in behavior.
"We want people to use these drugs carefully and pay attention," Robert J. Temple, MD, director of the FDA's office of medical policy, said at a news conference. "Stopping smoking is a goal we all want to work toward. We don't want to scare people off these drugs -- we just want them carefully monitored."
It's not at all clear that the drugs actually cause these behavior changes. Smokers are addicted to nicotine -- and when they quit, their withdrawal symptoms can include many bizarre behaviors, including suicide.
However, Curt Rosebraugh, MD, MPH, director of one of the FDA's drug evaluation units, said that some of the suicide reports came from Chantix users who were still smoking.
The FDA has been following reports of suicide and bizarre behavior in people taking Chantix. Indeed, the FAA bans use of the drug by pilots, and the FDA warns people not to operate heavy machinery while using the drug. But the link between such behaviors and Zyban is relatively new.
Zyban's active ingredient is bupropion, the antidepressant medication sold as Wellbutrin. While Wellbutrin and other antidepressants have labels warning of suicidal thoughts, the warning had not been fully extended to people taking Zyban to quit smoking.
"Our attention was focused on Chantix. It wasn't until we started looking through things that we realized Zyban may have the same issues," Rosebraugh said at the news conference.
The most disturbing reports to the FDA involve suicide:
- 98 completed suicides in Chantix users
- 14 completed suicides in Zyban users
- 188 attempted suicides in Chantix users
- 17 attempted suicides in Zyban users
These reports have not been fully investigated. There may be duplicate reports, and the reports have not been definitively shown to be drug side effects.
Rosebraugh said the smaller number of reports for Zyban does not necessarily mean the drug is safer than Chantix. Many more patients take Chantix -- and earlier reports of a suicide link spurred increase reporting of events possibly linked to use of the drug.
Pfizer, the drug giant that makes Chantix, says the drug remains an important tool for people who want to quit smoking.
"The purpose of the new boxed warning is to raise particular issue of concern to physicians so they can mitigate it, by being more vigilant and monitor patients more actively," Steve Romano, MD, Pfizer vice president and head of medical affairs, said at a news conference.
The FDA will require Pfizer and Zyban maker GlaxoSmithKline to conduct clinical trials to evaluate whether the companies' drugs actually cause suicidality and behavior change. Unlike the clinical trials upon which drug approval was based, the new studies will enroll smokers with underlying psychiatric disorders.
Romano noted that Pfizer already is conducting a clinical trial to assess Chantix's safety and effectiveness in people suffering from schizophrenia.
Suicide, and suicidal thoughts, have been linked to a wide variety of drugs, including antidepressants, antibiotics, acne drugs, and epilepsy drugs. However, Rosebraugh said there have been no suicide reports linked to the use of nicotine patches for smoking cessation.
GlaxoSmithKline did not respond to WebMD's request for comment and had not issued a news release by publication time.