Quitting smoking is clearly beneficial but a growing push by the pharmaceutical industry to encourage drugs for the purpose should be strongly resisted. Not only do most smokers successfully quit by other methods, an article published last week in PLoS One adds to the evidence that one such medication does more harm than good.
Pfizer’s controversial arrangement with the Pharmacy Guild of Australia to pay dispensing pharmacists for signing up consumers to support programs has been broadly criticised for various reasons.
Although the inclusion of the company’s smoking cessation treatment Champix (generic name varenicline) in the scheme has been so far overlooked, it’s significant given the particularly controversial history of the drug itself, and the broader debate around the effectiveness of pharmacotherapy for smoking cessation.
Varenicline is a prescription-only treatment that was listed on the Pharmaceutical Benefits Scheme in January 2008. It works by binding to nicotinic receptors, providing some stimulation at the receptor but also blocking nicotine.
The process may reduce withdrawal symptoms and nicotine cravings. Success rates among participants in varenicline clinical trials are reported to be around 22% continued abstinence after 12 months.
But as the National Prescribing Service has noted, clinical trials differ considerably from “real world” settings.
Trials for varenicline enrolled healthy people:
with no pre-existing medical or psychiatric conditions;
who were motivated to quit;
with moderate levels of nicotine dependence, and;
who were also provided with regular cessation advice and support.
Smokers across the general population have a considerably less salubrious profile, and there are also substantial differences in motivation between trial participants and the broader community.
Roughly half of Australians who were prescribed varenicline in the year after it was listed on the PBS stopped treatment within four weeks, compared to 11.4% of trial participants.
One potential explanation for the community drop-off rate is the range of associated side effects. Nausea, in up to one-third of those taking varenicline, insomnia, abnormal dreams, headache and constipation are commonly reported adverse effects.
Of greater concern is that the Therapeutic Goods Administration’s (TGA) August 2010 Medicines Safety Update reported that “psychiatric symptoms, including suicidal behaviour, continue to be reported with varenicline”.
By May 2010, the TGA had received 1025 reports of suspected adverse reaction, 67% (691) related to psychiatric symptoms including “depression, agitation, anxiety, altered mood and aggression” and reports of “206 suicide-related events among people taking varenicline, including 15 completed suicides”.
And concerns about this drug are not confined to Australia.
Since 2009, the US Food and Drug Administration (FDA) has required that varenicline packaging display “boxed” warnings, the strongest of all FDA warnings, about a possible link between the drug and the onset of neuropsychiatric adverse effects.
Health-care providers are also advised to closely monitor patients who are prescribed varenicline.
Despite such seemingly obvious concerns, varenicline is championed by many in a smoking cessation community increasingly committed to pharmaceutical approaches to quitting.
Belief that smokers are unable to quit without using varenicline, nicotine replacement therapy (NRT), buproprion (Zyban in Australia) or some other form pharmacotherapy has become so entrenched that a 2010 article reporting that the great majority of ex-smokers had quit without recourse to assistance and suggesting smokers be made aware of this fact, was roundly criticised in peer-reviewed journals and on the leading international tobacco-control online forum.
Criticism of the article was largely based on a clinical perspective of smoking cessation that’s preoccupied with rates of quitting associated with a particular treatment, as opposed to those who take a population-level perspective focusing on getting the greatest number of smokers to quit.
This situation has come to pass largely due the pharmaceutical industry’s aggressive promotion of its cessation treatments, often based on work by teams of researchers and consultants who report more favourable results than researchers not funded by industry.
Some two decades of such promotion notwithstanding, the reality of smoking cessation is that between two-thirds and three-quarters of former smokers quit without using NRT or other drugs or attending any sort of smoking cessation service. As few as 1% to 7% even call a quitline.
Pfizer Australia’s arrangement with pharmacists to sign smokers up to the Champix support scheme is only the most recent example of the industry’s clear commercial interest in undermining smokers’ confidence in their ability to quit “cold turkey”.
What’s even more worrying is that there’s a growing body of evidence that the drug they are promoting for this could be doing more harm than good.