Agomelatine is an atypical antidepressant drug developed on the basis that abnormal circadian rhythm causes depression While most other (typical) antidepressant drugs are selective serotonin reuptake inhibitors (SSRIs) that seek to increase serotonin in the brain, agomelatine activates melatonin (MT1 and MT2) receptors and blocks the 5-HT2C serotonin receptors . Presently, agomelatine is approved in the European Union for the treatment of major depression In the United States, it is presently under a phase 3 trial for regulatory approval, so it is considered a dietary supplement and doctors in the US do not prescribe agomelatine.