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Monday, February 4, 2008

Are Chantix Side Effects Worth the Risk?

The risks of continuing to smoke far outweigh the risks of trying to quit. Consider these facts:

  • One billion people will die from smoking in this century.
  • Half of persistent cigarette smokers are killed by their habit.
  • Smoking cessation at age 50 cuts this risk in half.
  • Smoking cessation before age 30 avoids almost all of the risk.
  • The success of smoking cessation improves by using nicotine gum; improves more by using Xyban; and improves even more by using Chantix.
  • About half of those who take Chantix remain non-smokers one year later.

Before Chantix (varenicline) was released by the FDA in the United States (in June 2006), it was clear that it caused minor side effects such as nausea, mood alterations, drowsiness, vivid dreams, or an allergic rash in up to one-third of patients. Many patients have reported these symptoms on Internet message boards. Now, after about 4 million smokers have taken Chantix, about 40 suicides have been reported to the FDA associated with Chantix and about 400 cases of suicidal thinking or behavior. In industry talk, these are called SAEs (serious adverse events), but individuals who experience an SAE (or their loved ones) appropriately use much stronger words.

All drugs have side effects, so doctors and patients considering starting a drug must always weigh the potential benefits against the risk of side-effects. (You can do the math using the above statistics.) Once you notice a side effect (or one is found by your doctor using laboratory tests), the severity of your side effects must be weighed against the benefit obtained by continuing the drug. Sometimes you and your doctor compromise by lowering the dose of the drug or switching to a different drug.

If you are an adult and feel blue (depressed), switching from Chantix to Zyban may be a good idea since Zyban is a low dose of an antidepressant (bupropion). If you get an itchy rash while taking Chantix, stop taking it until you can discuss this with your local pharmacist (free) or physician (good luck). Allergic reactions to drugs can become life-threatening if you ignore them and keep taking the drug.

This week, an FDA spokesperson said that “health care professionals should closely monitor patients for behavior and mood changes if they are are taking this drug.” However, in my opinion, it is much more reasonable to advise the patient and their family and friends about this risk. The press and legal community have already done an excellent job of warning people (judging from their websites). It is encouraging that the FDA has responded much more rapidly in releasing the preliminary results of “post-marketing surveillance” for newly released drugs (such as Chantix) since the Vioxx/Celebrex fiasco.

However, their surveillance system is passive, waiting for doctors and patients to report drug side effects. This means that the SAE rates are probably seriously underreported. Perhaps only 1% of SAEs which occur are reported to the FDA after a drug is approved for sale.

Many experts believe that to better protect the public, surveillance should be proactive, with costs and responsibilities to be shared by the FDA and the company which profits from sales of the drug. In my opinion, in the case of Chantix, pro-active surveillance could easily have been paid for by spending a small fraction of the 25% profit from the $681 million in 2007 sales of Chantix.

Smoking cessation is a process for most smokers, who are addicted to nicotine. Before turning to drug therapy, I suggest trying to quit with the help of a support group. Call the smoking cessation helpline in your state or country, such as 1-800-QUITNOW in the United States.

Now for some interesting disclosures. Most of the smoking statistics I listed at the top are from a research paper which you can download for free and read. The renowned first author of this paper, Sir Richard Doll, died at age 92, one year after it was published in the British Medical Journal. After his death, it was disclosed that he had received, but not reported, large consulting fees from chemical companies during his career.

Over the past 3 years, I have been paid a total of about $20,000 by Pfizer for reviewing the quality of spirometry tests done for a study of the effectiveness of Chantix in patients with COPD. My consulting for them on this project continues. Last year, Pfizer also paid me about $4,000 for helping them to produce educational videos to describe how spirometry should be used to evaluate diabetic patients for whom Exubera was being considered. To learn more about the fate of Exubera, click here.

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Posted by: Paul Enright MD at 5:36 pm


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