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Medicine for the Outdoors

Dr. Paul Auerbach is the world's leading outdoor health expert. His blog offers tips on outdoor safety and advice on how to handle wilderness emergencies.

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Chantix Precaution and the Outdoors

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The Institute for Safe Medication Practices recently released the following report, abbreviated and annotated by me for the purpose of this post, originally written by Thomas J. Moore (Senior Scientist, Drug Safety and Policy, ISMP), Michael R. Cohen RPh, MS, ScD (President, ISMP) and Curt D. Furberg, MD, PhD (Professor of Public Health Sciences, Wake Forest University School of Medicine).

Strong Safety Signal Seen for New Varenicline Risks


Executive Summary

A strong signal of multiple safety problems with Chantix (varenicline), a drug to help people stop smoking, has been seen in a pilot program to identify new drug risks in adverse drug events reported to the U.S. Food and Drug Administration.

Varenicline is suspected in various adverse drug event reports of causing a wide spectrum of injuries, including serious accidents and falls, potentially lethal cardiac rhythm disturbances, acute myocardial infarction, seizures, psychosis, aggression and suicide. The cases were analyzed and classified using computerized excerpts of adverse event reports that the FDA publishes for research use.

The FDA approved varenicline in May 2006 after granting it a priority review. Varenicline is a partial agonist of one of the nicotinic acetylcholine receptors in the brain and nervous system, and currently the only marketed and approved drug with this mechanism of action. It is prescribed for the purpose of (tobacco) smoking cessation.

In the 4th quarter of 2007, varenicline accounted for 988 serious injuries in the U.S. reported to the FDA. This large volume of reports prompted us to conduct an analysis of all adverse events for varenicline since marketing approval in 2006.

The FDA has recently issued a Public Health Advisory about one of the most marked adverse effects of varenicline, psychiatric symptoms, that included “changes in behavior, agitation, suicidal ideation, attempted and completed suicide.” However, the FDA alert provided no information about the numbers of reported neuropsychiatric events among treated smokers.

The adverse drug event reports for varenicline describe other kinds of serious harm for which no warnings now exist, either from the FDA or from the manufacturer, Pfizer Inc. The cases (including those with psychiatric effects) were classified using standardized medical queries developed by the pharmaceutical industry to identify potential adverse events in clinical studies and postmarket surveillance. Adverse event reports in themselves do not establish a causal link to the drug, only that an observer suspected a relationship. Depending on the features of the specific event, it could be counted in multiple categories, and classifications are not definitive. Among the most prominent were:

· Accidents and injuries. A total of 173 serious events described accidental injury, including 28 road traffic accidents and 77 falls, some leading to fractures of rib, facial bones, hand, ankle, spine, and lower limbs. In these cases a variety of potential causes were identified, including loss of consciousness, mental confusion, dizziness and muscle spasms.

· Vision disturbance. At least 148 reports contained medical terms indicating vision disturbances, including 68 cases described as blurred vision and 26 terms indicating transient or other forms of blindness. This reported effect could also describe a mechanism that could or did contribute to accidents and injuries.

· Heart rhythm disturbances. The FDA received 224 domestic reports classified as potential cardiac rhythm disturbances. This category, however, was dominated by reports of sudden loss of consciousness, an event that could also have non-cardiac causes. However, this category also included smaller numbers of cardiac arrests and identifiable abnormal cardiac rhythms

· Seizures and abnormal muscle spasms or movements. Serious reported events included 86 cases of convulsions (seizures), 372 reports of a wide variety of movement disorders, including tremors, muscle spasms, twitching, tics, drooling, and motor hyperactivity. The extent to which these problems resolved with a reduced dose or by halting treatment could not be determined from these data.

· Moderate and severe skin reactions. Reported serious events included 338 cases of hives or swelling of the tongue, face, eyes, lips or other areas.

· Diabetes. The FDA has received 544 reports suggesting varenicline may be related to a loss of glycemic (sugar) control. This category included many cases of weight loss or gain that could have alternative causes, but also identified numerous cases of symptoms and laboratory tests consistent with new onset diabetes.

Recommendations (per the report)

We have immediate safety concerns about the use of varenicline among persons operating aircraft, trains, buses and other vehicles, or in other settings where a lapse in alertness or motor control could lead to massive, serious injury. Other examples include persons operating nuclear power reactors, high-rise construction cranes or life-sustaining medical devices. Based on reports of sudden loss of consciousness, seizures, muscle spasms, vision disturbances, hallucinations, paranoia and psychosis, we believe varenicline may not be safe to use in these settings.

In addition, we recommend that patients and doctors exercise caution in the use of varenicline and consider the use of alternative approaches to smoking cessation.

Finally, we urge the FDA and the manufacturer to provide warnings to doctors and patients for those adverse effects that can be adequately documented through existing data, and to undertake on a priority basis epidemiological studies or other research to assess other potential risks."

MY COMMMENTS

Since the report paraphrased above was issued, the Federal Aviation Administration has banned the use of Chantix for pilots and air traffic controllers. Based on the information presented within this report, it seems prudent to avoid using Chantix if a person will encounter a potentially dangerous outdoor situation, in which one of the side effects might be expected to contribute to an accident. What was not presented in the report is any information about how soon adverse effects appear after Chantix is started. In other words, is a patient likely to expect side effects in the first week or month of using the medication? Are the side effects predictable or unpredictable? To what extent is there any interaction with pre-existing conditions, physiological state, interaction with other medications, diet, etc.?

Smoking cessation is extremely important, probably one of the top five most beneficial health activities that can be undertaken by anyone. As utilization data about the effects and side effects of Chantix are accumulated, we all hope that the benefits of using Chantix outweigh the risks. Until such time as we can determine the nature and true risk(s) of using this medication, it is prudent to recommend that it not be prescribed to persons who will be in any situation in which one of the above reported side effects, in particular alertness and motor control, would put the patient in peril.

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Dr. Paul S. Auerbach is the world’s leading authority on wilderness medicine.

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