Antidepressants have been available since the 1950s, when the monoamine oxidase inhibitors were first discovered. Since then, our armamentarium of antidepressants has progressively expanded with the discovery of the tricyclic antidepressants (TCAs) in the 1960s, the selective serotonin reuptake inhibitors (SSRIs) in the 1980s, and, subsequently, the serotonin norepinephrine reuptake inhibitors (SNRIs), and other agents possessing a diverse mechanism of action including buproprion, and mirtazapine.