What is the mechanism of action of venlafaxine?

Venlafaxine operates primarily as a serotonin-norepinephrine reuptake inhibitor (SNRI). This means it enhances the availability of the neurotransmitters serotonin and norepinephrine in the synaptic cleft by blocking their reuptake into the presynaptic neuron. This dual mechanism contributes to its effectiveness in treating conditions such as major depressive disorder and anxiety disorders, as both serotonin and norepinephrine play critical roles in mood regulation and emotional responses.

When venlafaxine is taken, it increases the levels of serotonin and norepinephrine in the brain, which can help alleviate symptoms of depression and anxiety. The unique action on both neurotransmitters differentiates it from medications that only target serotonin reuptake, providing a broader therapeutic effect for certain patients.

Other options provided do not accurately describe venlafaxine's mechanism of action, focusing instead on different neurotransmitter interactions or pathways that are not involved in its primary function. Thus, the correct understanding of venlafaxine as a selective reuptake inhibitor of norepinephrine and serotonin highlights its role in pharmacological treatment for various mood disorders.