Smoking cessation medications do not appear to increase the incidence of serious neuropsychiatric side effects, according to a study funded by the pharmaceutical industry.
It is the largest trial to look at the safety and efficacy of three first line smoking cessation treatments – varenicline, bupropion and nicotine patches – compared to placebo in smokers with and without psychiatric disorders.
“Clinicians should be comfortable prescribing the smoking cessation medication they feel would be most effective”
It found that smokers who took varenicline achieved higher abstinence rates than smokers on bupropion, nicotine patches, or placebo.
The EAGLES study, which involved more than 8,000 people, was requested by the US authorities following concerns about the neuropsychiatric safety of varenicline and bupropion.
Participants were adults aged 18-75 who smoked on average more than 10 cigarettes a day and who had previously tried to quit.
Half had a history of a past or current stable psychiatric condition including a mood, anxiety, psychotic, or borderline personality disorder, and some were taking psychotropic medication. The other participants did not have a psychiatric condition.
All participants were assessed to see whether they suffered any moderate-to-severe adverse neuropsychiatric events during and after treatment, including agitation, aggression, panic, anxiety, depression and suicide ideation.
Overall, there were more adverse neuropsychiatric events reported in the group with psychiatric disorders, than the control group. However, there were similar rates across all treatment arms – 6.5% for varenicline, 6.7% for bupropion, 5.2% for nicotine patch and 4.9% for placebo.
For smokers without a psychiatric disorder, there was no significant increase in the incidence of adverse neuropsychiatric events across the four treatment groups.
Varenicline was more effective in helping people quit than bupropion, nicotine patches, or placebo. Bupropion was about as effective as nicotine patches, and both were more effective than placebo.
Quit smoking drugs ‘do not’ cause neuropsychiatric effects
Overall, at 9-24 weeks, 21.8% of people on varenicline were continuously abstinent – 16.2% for bupropion, 15.7% for nicotine patches and 9.4% for placebo. Smokers with a psychiatric disorder achieved slightly lower abstinence rates than other smokers.
Lead author Professor Robert Anthenelli, from the University of California in San Diego, said: “The findings from this study… make it highly unlikely that varenicline and bupropion increase the risk of moderate-to-severe neuropsychiatric side effects in smokers without psychiatric disorders.
“We also show, for the first time, that the effectiveness of the medications is similar for smokers with or without psychiatric disorders,” said Professor Anthenelli.
He added: “The small increased incidence of adverse neuropsychiatric effects in people with stable psychiatric disorders, regardless of treatment, needs to be balanced against the known significant health risks of smoking.”
However, the study authors warned that the findings might not apply to those with untreated or unstable psychiatric illness. They also excluded people with alcohol or substance abuse disorders or who were at risk of suicide.
“The effectiveness of the medications is similar for smokers with or without psychiatric disorders”
The study, funded by Pfizer and GlaxoSmithKline, was published in The Lancet.
In a comment piece in the same journal, Dr Laurie Zawertailo, from the University of Toronto, said: “The findings from this study show that neuropsychiatric adverse events occurring during smoking cessation are independent of the medication used. Clinicians should be comfortable prescribing the smoking cessation medication they feel would be most effective for their patient.”
She added that patients trying to quit smoking, irrespective of method, should be made aware of the “small chance that severe changes in their mood and psychiatric well-being might occur” and that clinicians should monitor for such changes.
Tracy Kirk, a respiratory nurse consultant and primary health care educator, said: “As nurses, we are often one of the first points of contact for people looking to quit smoking – whether in a GP surgery or at a smoking cessation clinic.
“The findings from the EAGLES study highlight the benefits of smoking cessation medication and provides us with key information to help us have informed conversations with our patients who are looking to stop smoking,” she said.