**Question:** Centrally acting sympatholytic agent used as antihypertensive agent is:

A. Clonidine
B. Methyldopa
C. Reserpine
D. Guanfacine

**Core Concept:**

Centrally acting sympatholytic agents are medications that reduce sympathetic activity in the central nervous system, thereby lowering blood pressure. These agents act on alpha-2 receptors, which are found in the central nervous system and lead to a decrease in sympathetic outflow. In the context of antihypertensive therapy, reducing sympathetic activity helps to lower blood pressure.

**Why the Correct Answer is Right:**

A) Clonidine is a guanfacine agonist, which primarily targets alpha-2 receptors in the central nervous system. It is a centrally acting sympatholytic agent that can be used as an antihypertensive medication due to its ability to reduce sympathetic activity and lower blood pressure.

B) Methyldopa is a peripheral acting antihypertensive medication, primarily acting on alpha-2 receptors in the peripheral tissues. Although it can also have some central effects, its primary mode of action is peripheral, which is why it is not the correct answer for a central acting sympatholytic agent.

C) Reserpine is a vesicular monoamine transporter inhibitor that reduces norepinephrine and dopamine reuptake in the synaptic cleft. While it can lower blood pressure, it is not a centrally acting sympatholytic agent. Reserpine is a peripheral acting antihypertensive medication that acts on the peripheral sympathetic nervous system.

D) Guanfacine is a centrally acting alpha-2 agonist that reduces sympathetic activity in the central nervous system, making it an appropriate choice for an antihypertensive agent.

**Why Each Wrong Option is Incorrect:**

A) Methyldopa: Although it has central effects, its primary mode of action is peripheral-acting, making it an incorrect choice for a centrally acting sympatholytic agent.

B) Reserpine: Although it lowers blood pressure, it is a peripheral acting antihypertensive medication and does not target alpha-2 receptors in the central nervous system, making it an incorrect choice for a central acting sympatholytic agent.

C) Guanfacine: Although a centrally acting alpha-2 agonist, it is not the correct answer for a central acting sympatholytic agent.

**Clinical Pearls:**

1. Guanfacine is primarily used for the treatment of attention deficit hyperactivity disorder (ADHD) and tic disorders like Tourette's syndrome.
2. Methyldopa is commonly used for the treatment of hypertension and pheochromocytoma patients who cannot receive alpha-blocking agents due to their cardiovascular side effects.
3. Reserpine is used for the treatment of hypertension, but its side effects on the cardiovascular system and the risk of orthostatic hypotension make it a less preferred choice compared to guanfacine, methyldopa, and other centrally acting alpha-2 agonists.

**Explanation:**

Centrally acting