**Question:** A cardiac patient must be asked to stop one of the following drugs when he is coughing a lot

**Core Concept:** Understanding which medications can cause cough in cardiac patients and their clinical implications.

**Why the Correct Answer is Right:**
Correct Answer: C. ACE inhibitors (Angiotensin-Converting Enzyme inhibitors)

Option A: Angiotensin II receptor blockers (ARBs) - These drugs do not cause cough.
Option B: Beta-blockers - While beta-blockers can cause dry cough in some patients, it is less common than ACE inhibitors.
Option D: Diuretics - Diuretics are not primarily known to cause cough, although they can indirectly affect the respiratory tract.

**Why Each Wrong Option is Incorrect:**
Option A (ARBs): Although ARBs can cause fluid retention and worsen cough in some patients, they are not directly responsible for cough onset.
Option B (Beta-blockers): Although beta-blockers can cause cough, this side effect is less common compared to ACE inhibitors.
Option D (Diuretics): While diuretics can indirectly affect the respiratory tract, they are not primarily known to cause cough.

**Clinical Pearl / High-Yield Fact:**
Cardiac patients on ACE inhibitors should be monitored for cough and switched to an alternative medication like ARBs if cough develops, as ACE inhibitors can worsen pre-existing respiratory conditions and cause respiratory distress.

**Why the Correct Answer is Right:**
ACE inhibitors (Option C) are commonly prescribed for cardiac patients, including those with pre-existing respiratory conditions. These medications work by blocking the angiotensin II, leading to reduced vasoconstriction and increased aldosterone levels. This can result in higher levels of angiotensin II, which plays a role in the development of cough in susceptible patients.

Cough is a common side effect of ACE inhibitors and can lead to worsening of pre-existing respiratory conditions and respiratory distress in some patients.

In summary, when a cardiac patient experiences cough while on ACE inhibitors, it is important to consider switching them to alternative medications like Angiotensin Receptor Blockers (ARBs), which are less likely to induce cough compared to ACE inhibitors.