Varenicline can be prescribed for patients with stably treated current or past depression without worsening their depression, suggest results of a randomised, controlled surveillance study published today in the Annals of Internal Medicine.
Around half of smokers who seek help to quit have a history of depression, and they find it more difficult to quit than those who have never had clinical depressions. Studies have shown that varenicline boosts quit rates among smokers without depression, but case reports and post-marketing adverse event reports have raised concerns about the drug's neuropsychiatric safety profile in psychiatric patients.
The MHRA warns that patients with a history of psychiatric illness should be monitored closely when taking varenicline and should be advised to stop taking it if they develop agitation or depression.
The new study – funded by manufacturer Pfizer – was set up specifically to address this issue and recruited 525 adults from eight countries who smoked at least 10 cigarettes a day and were motivated to stop smoking. All had stably treated current or past major depression and no recent cardiovascular events.
They were randomised to receive varenicline 1 mg twice daily or placebo for 12 weeks and were then followed for 40 weeks. Overall, 68% of the varenicline group and 67% of the placebo group completed the study.
At the end of the 40-week follow-up, 20.3% of the varenicline group had quite compared with 10.4% in the placebo group.
Importantly, the researchers note, there were "no clinically relevant" between-group differences in mood, anxiety, or thoughts about suicide, and no overall worsening of depression or anxiety in either group.