Major study shows no increased suicide risk from smoking cessation drugs
- A new large study of two smoking cessation drugs from Pfizer and GlaxoSmithKline showed the pills do not increase suicidal behavior or other neuropsychiatric adverse events, after years in which sales were dampened due to perceived risks.
- Pfizer and GlaxoSmithKline (GSK) co-sponsored the Eagles trial, which is the largest double-blind, smoking cessation drug trial to date. The trial included 8,144 smokers, 45% of whom had current or previous psychiatric problems, such as depression, anxiety, PTSD, or schizophrenia.
- Overall, Pfizer's Chantix was the most effective smoking cessation drug, compared with the other treatment arms (GSK's Zyban, nicotine patch, or placebo). In terms of the occurrence of serious neuropsychiatric events, incidence rates in patients without a history of psychiatric disorders were lower in both the Chantix and Zyban arms compared to the placebo group.
The results of the EAGLES study could be considered a vindication of sorts for Pfizer. But Chantix sales have been negatively impacted by the FDA-mandated black box warning over the past seven years. The drug pulled in $671 million in sales last year, down from $846 million in 2008. GSK's Zyban, on the other hand, has been off-patent for ten years.
Smoking continues to be a leading cause of preventable death in the US, where roughly 440,000 people died from smoking-related causes last year. Globally, that figure hit 6 million. While this study was manufacturer sponsored, it could help change the poor image of smoking-cessation drugs by demonstrating lower incidence of neuropsychiatric events than previously thought.
“Clinical practice guidelines recommend that the most effective way for smokers to quit is by combining a smoking cessation medication with counseling. However, smoking cessation support is often underutilized, due in part to misperceptions about the effectiveness and safety of smoking cessation medicines,” said lead study investigator Robert M. Anthenelli.
The data clearly showed a higher risk of neuropsychiatric events in patients with a history of psychiatric problems. Among those with a history, the rate of serious neuropsychiatric events was 6.5% in both the Chantix and Zyban groups and 4.9% in the placebo arm.
This is not surprising, considering the fact that their baseline characteristics would suggest a higher tendency towards psychiatric events in general. Moreover, smokers tend to have higher rates of psychiatric problems than non-smokers.
With respect to efficacy, at the end of 24 weeks (12-week trial plus 12-week follow-up), 22% of Chantix-treated patients had not resumed smoking, compared with 16% of Zyban-treated patients, 16% of patients who wore the patch, and 9% of placebo-treated patients.
Pfizer plans to ask the FDA to remove the black-box warning on Chantix, according to Stat.