Which medication is most likely used specifically for depression?

Mirtazapine is recognized as a medication specifically used to treat major depressive disorder. It belongs to the class of medications known as atypical antidepressants. Mirtazapine operates by enhancing the release of certain neurotransmitters, particularly norepinephrine and serotonin, which are crucial in regulating mood. This unique mechanism makes it effective in addressing the symptoms of depression through its influence on various receptors in the brain.

While other options listed, such as escitalopram, venlafaxine, and citalopram, are also antidepressants and may be utilized for treating depression, mirtazapine is particularly noted for its unique sedative properties and its ability to stimulate appetite, which can be especially beneficial in patients who present with both depression and weight loss. This differentiates mirtazapine from the selective serotonin reuptake inhibitors (SSRIs) like escitalopram and citalopram, and the serotonin-norepinephrine reuptake inhibitor (SNRI) venlafaxine, all of which have different profiles and side effects.

In summary, mirtazapine's specific use in treating depression, particularly in cases complicated by insomnia or weight loss, aligns with the characteristics noted in the question