Pfizer has reported positive results from EAGLES, a multi-centre, parallel-group, post-authorisation, safety study / post-marketing requirement (PASS / PMR), which was conducted in 16 countries in collaboration with GlaxoSmithKline.

The Evaluating Adverse Events in a Global Smoking Cessation Study (EAGLES) clinical trial of approved smoking cessation medicines, has showed that the smokers treated with Chantix / Champix (varenicline) had higher quit rates than those treated with bupropion, nicotine patch or placebo.

Claimed to be the biggest clinical trial on quitting smoking, the trial included 8,144 adult smokers and was designed to compare the neuropsychiatric safety of Chantix / Champix (varenicline) and bupropion with placebo and nicotine patch in adult smokers with and without a history of psychiatric disorders.

The authors of the EAGLES stated that the trial did not show a major increase in the incidence of the composite primary safety endpoint of serious neuropsychiatric adverse events with Chantix / Champix (varenicline) or bupropion, compared to placebo and nicotine patch.

“Patients treated with each of the medications showed higher abstinence rates than those treated with placebo.”

Differences between incidence rates were considered major if their associated 95% confidence intervals (CIs) were entirely above or below zero.

Around half of the trial participants had a history of psychiatric disorders, either past and in remission or present and clinically stable, and the psychiatric diagnoses of the trial included primarily depressive, bipolar, anxiety and psychotic disorders.

EAGLES also included an efficacy objective to verify smoking abstinence rates in patients treated with Chantix / Champix (varenicline) or bupropion, relative to placebo, during the last four weeks of the 12-week treatment period.

Continuous abstinence was also evaluated relative to the nicotine patch, and longer-term abstinence through a 12-week, non-treatment follow-up period (weeks nine to 24) was also evaluated for all treatments.

The results further showed that patients with and without a history of psychiatric disorders taking Chantix / Champix (varenicline) had significantly higher continuous abstinence rates than patients treated with bupropion or nicotine patch during both time periods.

Patients treated with each of the medications showed higher abstinence rates than those treated with placebo.

Said to be the first placebo-controlled trial of this size, the trial aimed to directly compare the efficacy of Chantix / Champix (varenicline), bupropion and nicotine patch to help people quit smoking.

Conducted at the request of, and designed in consultation with, the US Food and Drug Administration (FDA) and the European Medicines Agency (EMA), the study aimed to compare the risk of clinically significant neuropsychiatric events, including but not limited to suicidality, in individuals using Chantix / Champix (varenicline), bupropion, nicotine replacement therapy or placebo as aids to smoking cessation across 12 weeks of treatment.

The study also sought to determine whether individuals with a history of psychiatric disorders are at greater risk for developing clinically significant neuropsychiatric events, compared to individuals without a history of psychiatric disorders, while using Chantix / Champix (varenicline) or bupropion as an aid to smoking cessation.

With data limitations of the trial included, the findings may not generalise to smokers with untreated or unstable psychiatric disease, and the trial had limited power to detect rare neuropsychiatric events.