New study of Chantix in comparison with NRT

Recently there has been some concern over side-effects experienced by a minority of people using Chantix (varenicline). Although Chantix had a remarkably good safety and efficacy record in the clinical trials conducted prior to its launch, those trials excluded patients with complex medical or psychiatric problems (normal practice in pre-approval clinical trials). So when a number of patients (albeit a tiny proportion of the millions who have used Chantix) have reported unpleasant and serious mood disturbances or even suicidal thoughts and acts while taking Chantix since it was launched, this has led to a concern that perhaps Chantix may have more serious side-effects in regular patients with complex medical and psychiatric problems.

A new study by John Stapleton and colleagues was published this week in the journal, Addiction, that addressed this issue. The study reports on the clinical outcomes of 412 patients being treated at a tobacco dependence clinic in London, UK. 204 patients were treated with nicotine replacement therapy (NRT) between May and November, 2006 (prior to Chantix being launched in the UK), and 208 patients were treated with Chantix from January to April 2007. Although the two groups were not randomly allocated to treatments, they were very similar on a number of baseline measures - for example 47% of those treated with NRT were men and 50% of those treated with varenicline were men. The daily cigarette consumption of the two groups was 21 and 22 cigarettes per day respectively. The only signs of baseline differences between the groups were that 69% of those treated with NRT were white, compared with 79% of those treated with Chantix. Those treated with Chantix also rated themselves as being slightly more “determined to quit” at baseline. All of the patients were treated in weekly stop-smoking groups for 7 weeks, with the target quit date coming at the third group meeting. Some of the patients using NRT used “combination” NRT (typically the patch plus either nicotine gum, lozenge, nasal spray or inhaler). At the end of group treatment (i.e. four weeks after the target quit date), 66% of those using a single NRT, 75% of those using combination NRT and 80% of those using Chantix were no longer smoking (not a puff in the previous two weeks). So Chantix produced higher quit rates than a single NRT product, but similar to combination NRT.

111 of these patients were receiving treatment for a mental illness, and the pattern of results for those patients was similar to that of the group as whole, with higher quit rates for those using Chantix. In the whole sample, those using Chantix reported significantly lower craving scores, with no differences on ratings of withdrawal symptoms (e.g. irritability, poor concentration, etc).

An analysis of adverse drug reactions found only one that was more commonly reported with NRT than with Chantix (skin irritation related to patch use). However, 12 symptoms were reported more frequently among those using Chantix. Those symptoms were, nausea (38%), disturbed sleep (30%), vivid dreams (13%), drowsiness (12%), constipation (11%), headache (10%), dyspepsia (8%), dry mouth (7%), bad taste (7%), depression/low mood (5%), diarrhoea (5%), and disorientation/confusion (5%). 7 patients reported moderate/severe anxiety/panic while on Chantix, compared with only one on NRT. Two patient had adverse reactions while using Chantix that were of sufficient severity to be reported to the Medicine’s Regulatory Authority in the UK. One of these was for a “severe psychological reaction likened to a bad LSD trip, including anxiety, paranoia, and confusion.”

It should be noted that around 80% of the patients in this study had previous experience trying to quit smoking using NRT. It is possible that those taking the new drug (Chantix) would have a stronger tendency to note side effects than those using an NRT that they were familiar with.

Overall, these results are broadly consistent with the evidence from clinical trials and post-launch clinical experience with Chantix. They are consistent with the ideas that (a) Chantix may result in slightly higher chances of success in quitting smoking than another single medicine/NRT (b) Quitting success rates on Chantix are broadly similar to those with combination NRT, (c) Chantix results in more side effects than NRT, of which some are common (e.g. nausea, disturbed sleep and vivid dreams) and some less common (<5%) – including depressed mood, disorientation and anxiety. The single patient experiencing a severe psychological reaction while using Chantix may be an indication that such reactions can occur but are rare (<1%).

It should be noted that all of the patients in this study were being treated in a specialist tobacco treatment clinic, within the context of support groups facilitated by experienced clinicians. In that context adverse effects of medications can be monitored, and if necessary patients promptly switched to different medications. Many of the psychological side effects were 3-5 times more common among patients using Chantix than among patients using NRT.

The research continues to show that Chantix is an effective drug for smoking cessation, that offers renewed hope for those who have tried and failed with other treatments. However, I think patients who are not planning on maintaining regular contact with an experienced clinician during their quit attempt (i.e. a clinician who can monitor side effects and provide supportive advice on a regular basis) should give serious consideration to using combination NRT (patch plus one other NRT) as a first choice. This treatment has the advantage that the patient is not taking a “new drug” – just the same one (nicotine) they have been taking, but without the 4000 other toxic chemicals.
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About the Author

MA, MAppSci, PhD

Dr. Jonathan Foulds is an expert in the field of tobacco addiction.