Effects of short-term varenicline administration on cortisol in healthy, non-smoking adults: a randomized, double-blind, study.

RATIONALE: Varenicline is the most effective drug for smoking cessation, but its use decreased because of reports of depressogenic side effects. However, because smoking and smoking cessation on their own are associated with depression, it remains unclear whether reported depressogenic effects are attributable to varenicline, or to smoking, and/or smoking cessation themselves. OBJECTIVES: Previously, we observed no depressogenic effects of varenicline on a psychological level. In the present study, we aimed at investigating potential depressogenic effects of the partial nicotinergic acetylcholine receptor agonist varenicline on a biological level. A possible pathway would be an effect of varenicline on the hypothalamic-pituitary-adrenal (HPA) axis, considering the relation between the HPA axis and (1) the cholinergic system and (2) depression. METHODS: In a randomized, double-blind design, we administered varenicline or placebo for 7 days (0.5 mg/day first 3 days, then 1 mg/day) to healthy never-smoking subjects, thereby eliminating bias by (previous) smoking status. We used repeated measures (before and after treatment) of the salivary free cortisol awakening response to measure HPA axis activity and flexibility. RESULTS: Salivary cortisol data of 34 subjects were included in the analysis. Results showed no effect of varenicline on height (F₁,₃₂ = 0.405; P = 0.529) or shape (F₂,₃₁ = 0.110; P = 0.164) of the cortisol awakening response. CONCLUSIONS: Results do not suggest depressogenic effects of varenicline on the HPA axis. Although this does not preclude other biological depressogenic effects of varenicline, it seems that concerns about effects of varenicline on the HPA axis should not limit its potential to treat nicotine and related addictions.