Final answer:
Mirtazapine (Remeron) is an alpha-2 receptor antagonist used to treat depression. It has a high toxic dose, mild side effects, and is widely prescribed.
Step-by-step explanation:
The alpha-2 receptor antagonist used to treat depression as an antidepressant is mirtazapine (Remeron). Mirtazapine works by inhibiting the reuptake of serotonin, which increases its availability in the brain and also acts as an antagonist to the alpha-2 adrenergic receptors. This dual action contributes to its therapeutic effects in the treatment of depression.
While mirtazapine does inhibit reuptake of serotonin it is important to note that it does so indirectly by antagonizing the alpha-2 receptors which is different from the mechanism of selective serotonin reuptake inhibitors (SSRIs). Mirtazapine is known for its high toxic dose and generally mild side effects and these characteristics along with its efficacy, make it one of the most widely prescribed antidepressants in many countries.