Do Popular Anti-Smoking Medications Increase Suicide Risk?

Although tobacco use is responsible for one in five deaths in the United States each year and adds more than $193 billion to health care costs, it remains one of the most treatment-resistant forms of substance abuse known.  Considering  the difficulties that smokers face in quitting "cold turkey", physicians often prescribe a variety of nicotine replacement products to help their patients end their smoking habit.  These products include transdermal patches that release nicotine into the skin as well as antidepressant such as buproprion (marketed as Wellbutrin or Zyban) and varenicline (marketed as Chantix in the United States and Champix in other countries).    

While nicotine withdrawal has been known to cause a variety of psychological symptoms including irritability, insomnia and weight gain, depression and suicidal thinking is not commonly found in patients trying to quit smoking.   Unfortunately, incidents of suicide in patients who have been prescribed buproprion and varenicline have led the Food and Drug Administration to issue Boxed Warnings to physicians prescribing these medications to patients who smoke.  Patients prescribed these medications are also issued a mandatory Medication Guide warning of possible psychiatric effects including suicidal behaviours and depression. 

But do these popular smoking cessation products increase suicide risk?  In a recent study published in the Public Library of Science journal PLoS One, a team of researchers compared clinical case reports examining health risks in using varenicline and buproprion for smoking cessation.  Led by Thomas J. Moore of the Institute for Safe Medication Practices and Curt D. Furberg of the Division of Public Healh Sciences, Wake Forest University, the researchers examined FDA case reports from 1998 through September 2010 using the FDA's Adverse Event Reporting System.  All of the case reports were based in the United States and involved a serious medical outcome (i.e., death or hospitalization).  As a comparison group, they researchers also included case reports for other nicotine replacement products and combined case reports for several commonly used antibiotics.    All case reports were examined for incidents of suicidal or self-harm behaviour and possible interactions with other medications being taken at the same time were also considered.   A total of 17,290 case reports were examined including 13,243 cases in the smoking cessation group and 4,047 in the antibiotic comparison group.   In the smoking cessation group, 3,249 cases (25% of the total) showed evidence of suicide attempts or self-harm behaviour compared to only 48 cases in the antibiotic group (1 % of the total).   Although some differences were found between smoking cessation and antibiotic populations (antibiotics users had a wider age range for example),  the overall demographics were similar across all the compared groups.

Of the smoking cessation medications specifically examined by the researchers, varenicline showed the greatest risk although buproprion showed an elevated risk for suicidal behaviour as well.  There was no difference between risk for suicide attempts or self-harm behaviour when examined separately.  Compared to the antibiotic group, risk of suicidal behaviour was elevated for all three smoking cessation groups although non-prescription nicotine replacement treatment showed the lowest suicide risk.    Related symptoms, including headaches and pain, were also higher in the smoking cessation groups compared to the antibiotic group although this may be related to nicotine withdrawal.  Overall, varenicline showed the highest suicide risk despite it being a relatively new product (varenicline was only available to patients for four years during the thirteen-year period that the study examined).   Of the 3,249 cases of suicidal behaviour  specifically linked to smoking cessation products,  2,925 (90 %) involved varenicline.   Only 229 cases (7%) involved buproprion and 95 (3%) involved nicotine replacement therapy.   For completed suicides, 272 of the 295 cases examined involved varenicline.   

In examining these results, the researchers concluded that varenicline showed a markedly higher overall risk compared to all other smoking cessation products.  While buproprion shows an elevated risk as well, the authors warn that varenicline, under its brand name of Chantix, should not be prescribed for first-line use in helping patients quit smoking.     While mandatory health warnings are included by Pfizer in its advertising for Chantix, patients hoping to quit smoking are advised to warn their doctors and the FDA of any suicidal thoughts that develop after taking the medication. 

 

Comments

[Nicholas Kilzer]

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[Romeo Vitelli]

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