What is the mechanism by which venlafaxine works as an antidepressant?

Venlafaxine operates as a serotonin-norepinephrine reuptake inhibitor (SNRI), making option C the correct choice. The mechanism involves the inhibition of both serotonin and norepinephrine reuptake transporters, which leads to increased levels of these neurotransmitters in the synaptic cleft.

By blocking the reuptake, venlafaxine enhances synaptic availability of serotonin, a neurotransmitter critical in mood regulation, while also increasing norepinephrine, which plays a role in arousal and alertness. This dual-action is particularly beneficial for patients with depression and anxiety disorders, as it encompasses a broader range of neurotransmitter influences that may contribute to their symptoms.

In contrast, the other options are inaccurate in detailing the drug's mechanism. Simply inhibiting norepinephrine reuptake does not account for venlafaxine's effects on serotonin levels. Exclusively blocking serotonin reuptake omits the important role of norepinephrine inhibition. Additionally, enhancing dopamine reuptake is not relevant since venlafaxine primarily targets serotonin and norepinephrine without directly affecting dopamine reuptake mechanisms. Thus, the correct understanding of venlafaxine's function emphasizes its capability to inhibit both serotonin and norepinephrine reupt