Mirtazapine, originally known as ORG 3770, was first synthesized by the Department of Medicinal Chemistry of NV Organon in the Netherlands (Kaspersen et al. 1989). First approved for use in major depression in the Netherlands in 1994, mirtazapine was introduced in the United States in 1996. The antidepressant mirtazapine has a dual mode of action. It is a noradrenergic and specific serotonergic antidepressant (NaSSA) that acts by antagonizing the adrenergic alpha2-autoreceptors and alpha2-heteroreceptors as well as by blocking 5-HT2 and 5-HT3 receptors. It enhances, therefore, the release of norepinephrine and 5-HT1A-mediated serotonergic transmission. This dual mode of action may conceivably be responsible for mirtazapine's rapid onset of action.