Agomelatine in the treatment of seasonal affective disorder

Rationale The novel antidepressant agomelatine acts as a melatonergic (MT1 and MT2) receptor agonist and as a serotonin-2C receptor antagonist. Previous studies showed that agomelatine is able to restore disrupted circadian rhythms, which were implicated in the pathophysiology of seasonal affective disorder (SAD). Objectives The aim of this study was to investigate the efficacy and tolerability of agomelatine in the treatment of SAD. Materials and methods Thirty-seven acutely depressed SAD patients were included in an open study with agomelatine (25 mg/day in the evening) over 14 weeks. Efficacy assessments included the Structured Interview Guide for the Hamilton Depression Rating Scale (SAD version; SIGH-SAD), the Clinical Global Impression of Severity (CGI-S) and Improvement (CGI-I), the Circscreen, a self-rating scale for the assessment of sleep and circadian rhythm disorders, and the Hypomania Scale. Results Agomelatine led to a progressive and statistically significant decrease of SIGH-SAD, CGI-S, and CGI-I scores from week 2 onward (p < 0.001). Furthermore, scores on the Circscreen improved significantly during the study (p < 0.001). Treatment with agomelatine over 14 weeks yielded a response rate of 75.7% (SIGH-SAD < 50% of baseline value) and a remission rate (SIGH-SAD < 8) of 70.3% in the intention to treat sample. Scores on the Hypomania Scale were consistently low during the study. Agomelatine showed good overall tolerability: throughout the study only one adverse event (mild fatigue) was related to the study drug. Conclusions The results of this study suggest that seasonal depression may be effectively and safely treated with agomelatine.