**Question:** True statement regarding inverse agonist is:

A. Inverse agonists reduce the activity of a receptor by binding to it and promoting an increase in the intrinsic activity of the receptor.
B. Inverse agonists reduce the activity of a receptor by binding to it and preventing the receptor from increasing its activity.
C. Inverse agonists reduce the activity of a receptor by binding to it and reducing its activity.
D. Inverse agonists reduce the activity of a receptor by binding to it and promoting its activity.

**Correct Answer:** C. Inverse agonists reduce the activity of a receptor by binding to it and reducing its activity.

**Core Concept:**
An inverse agonist is a drug or molecule that binds to a receptor and decreases the receptor's activity, thereby reducing the physiological response mediated by that receptor. In contrast to regular agonists, which activate receptors and increase physiological responses, inverse agonists work by counteracting the actions of endogenous agonists (e.g., neurotransmitters) and modulating the receptor's activity.

**Why the Correct Answer is Right:**
Inverse agonists act on receptors by binding to them and preventing the receptor from increasing its activity. This means that they do not simply neutralize the effects of endogenous agonists (which would be the case for full or partial agonists), nor do they simply block the receptor (which would be the case for antagonists). Instead, inverse agonists modulate the receptor's activity, reducing the overall effect on the physiological response.

**Why Each Wrong Option is Incorrect:**
A) Inverse agonists do not promote receptor activity, but rather reduce it. This option contradicts the definition of an inverse agonist.
B) Inverse agonists do not prevent the receptor from increasing its activity, but rather bind to the receptor and prevent it from decreasing its activity. This option is incorrect as it does not accurately describe the mechanism of action of inverse agonists.
D) Inverse agonists do not promote receptor activity, but rather reduce it. This option contradicts the definition of an inverse agonist.

**Why Option C is Right:**
Option C accurately describes the action of inverse agonists as binding to receptors and reducing their activity, thereby counteracting the effects of endogenous agonists and modulating the overall physiological response. This is in line with the definition of inverse agonists.

**Why Each Wrong Option is Incorrect:**
A) Inverse agonists do not promote receptor activity, but rather reduce it. This option contradicts the definition of an inverse agonist.
B) Inverse agonists do not prevent the receptor from increasing its activity, but rather bind to the receptor and prevent it from decreasing its activity. This option is incorrect as it does not accurately describe the mechanism of action of inverse agonists.
D) Inverse agonists do not promote receptor activity, but rather reduce it. This option contradicts the definition of an inverse agonist.

**Clinical Example:**
An inverse agonist might be used in medications targeting G-protein coupled receptors (GPCRs), such as beta-2 adrenergic receptors in asthma treatment. Inhaled beta-2 agonists, like salbutamol and terbutaline, are classical agonists that