The Executive Summary of the report made two main recommendations:
- Chantix should be avoided or used with caution by persons operating aircraft, motor vehicles or other machines where a lapse in alertness or motor control could have serious consequences.
- Patients and doctors should exercise caution in the use of Chantix and “consider the use of alternative approaches to smoking cessation.”
These are strong recommendations, and have immediately resulted in the Federal Aviation Authority (FAA) and Federal Motor Carrier Safety Administration (FMCSA) adding varenicline to their list of drugs that should not be used by pilots or truck drivers.
There are a number of fundamental problems with the quality of the data, analysis and interpretation in the ISMP report. The report fails to consider the frequency of the use of the drug when considering the number of adverse events being reported. The report also fails to adequately consider the possibility that some of the reported adverse events may have been caused by nicotine withdrawal. It is entirely plausible that many of these reported symptoms were caused by nicotine withdrawal rather than Chantix. In fact in the placebo-controlled trials of Chantix, withdrawal symptoms were reduced in those using Chantix!
In addition, the report does not adequately consider that a high proportion of patients using smoking cessation medications are already suffering from or at very high risk for smoking-caused illnesses, including some mentioned as adverse events in the report (cardiac arrhythmias). The report inaccurately characterizes the relative efficacy of varenicline versus other treatments.
The ISMP report states that Chantix has similar long term quit rates to nicotine gum. This statement contradicts the findings of the new US Public Health Service Clinical Practice Guideline on Treating Tobacco Use and Dependence, which found that quit rates with varenicline are significantly greater than with the nicotine patch or gum.
The Guideline, written after the recent labeling changes for varenicline, concluded that “Varenicline is an effective smoking cessation treatment that patients should be encouraged to use.” When added to the other problems of interpretation mentioned above, it seems most prudent to rely on the recommendation of the US Clinical Practice Guideline, which resulted from a very thorough review of the available scientific evidence.
Pfizer stated that it did not see an increase in psychiatric events in patients taking Chantix compared with placebo during its own clinical trials.
Pfizer recently announced that it is conducting additional studies in several patient populations, including people suffering from schizophrenia, heart disease, emphysema, as well as adolescents. Also, the company plans on publishing the results later this year of an in-depth analysis of the psychiatric events seen in patients taking Chantix.
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