A patient with major depressive disorder is started on venlafaxine. Which class of antidepressant does this medication belong to?
Correct Answer: D
Rationale: Venlafaxine is classified as a serotonin-norepinephrine reuptake inhibitor (SNRI). SNRIs work by increasing the levels of both serotonin and norepinephrine in the brain, which helps alleviate symptoms of depression. This mechanism of action distinguishes SNRIs from other classes of antidepressants like SSRIs, TCAs, and MAOIs, making venlafaxine an effective choice for patients with major depressive disorder. Therefore, the correct answer is D. Choice A, SSRIs, primarily target serotonin reuptake only. Choice B, TCAs, work by inhibiting the reuptake of norepinephrine and serotonin, but they are not as selective as SNRIs. Choice C, MAOIs, inhibit the enzyme monoamine oxidase, leading to increased levels of various neurotransmitters, including serotonin and norepinephrine, but they are typically used as second- or third-line agents due to dietary restrictions and potential side effects.