**Question:** True regarding bupropion is: September 2009

A. Bupropion is a dopamine reuptake inhibitor.
B. Bupropion is a norepinephrine reuptake inhibitor.
C. Bupropion is a selective serotonin reuptake inhibitor (SSRI).
D. Bupropion is a selective norepinephrine and dopamine reuptake inhibitor (SNDRI).

**Core Concept:**
Bupropion is an antidepressant drug used to treat major depressive disorder, bipolar disorder, and smoking cessation. It acts as an inhibitor of neurotransmitter reuptake, meaning it prevents the reabsorption of neurotransmitters like dopamine, norepinephrine, and serotonin from being taken back into neurons after they have been released into the synaptic cleft.

**Why the Correct Answer is Right:**
Bupropion is a selective norepinephrine and dopamine reuptake inhibitor (SNDRI). It selectively inhibits the reuptake of norepinephrine and dopamine, rather than serotonin. This selective action on dopamine and norepinephrine neurotransmission is responsible for its antidepressant and smoking cessation effects.

**Why Each Wrong Option is Incorrect:**

A. Bupropion is incorrectly described as a dopamine reuptake inhibitor. In reality, it is a selective norepinephrine and dopamine reuptake inhibitor (SNDRI).
B. Bupropion is not a norepinephrine reuptake inhibitor; it is a selective norepinephrine and dopamine reuptake inhibitor (SNDRI). The misconception here is the separation of its action on norepinephrine and dopamine.
C. Bupropion is not an SSRI (selective serotonin reuptake inhibitor). As explained, it is a selective norepinephrine and dopamine reuptake inhibitor (SNDRI). The misconception here is the separation of its action on serotonin and the correct classification as an SNDRI.
D. Similarly to option C, bupropion is not classified as an SNRI (selective norepinephrine and serotonin reuptake inhibitor). It is a selective norepinephrine and dopamine reuptake inhibitor (SNDRI).

**Clinical Pearl:**
The misconception in options A, B, C, and D is due to the confusion between selective serotonin reuptake inhibitors (SSRIs) and selective norepinephrine and dopamine reuptake inhibitors (SNDRIs). SNDRIs have a broader spectrum of action on neurotransmitters, including norepinephrine and dopamine, which is different from the selective action of SSRIs on serotonin. This distinction is essential for understanding the pharmacodynamics and therapeutic effects of bupropion and other medications acting as SNDRIs.