Cardiovascular Drugs — MCQs

Cardiovascular Drugs Indian Medical PG Practice Questions and MCQs

Question 541: Which of the following lipid-lowering drugs acts by inhibiting HMG-CoA reductase?

A. Resins
B. Statins (Correct Answer)
C. Fibric acid derivatives
D. Bile acid sequestrants

Explanation: **Explanation:** **Statins (HMG-CoA Reductase Inhibitors):** Statins are the most potent drugs for lowering LDL cholesterol. They act by competitively inhibiting **3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase**, the rate-limiting enzyme in hepatic cholesterol synthesis. This inhibition decreases intracellular cholesterol, leading to an **upregulation of LDL receptors** on the surface of hepatocytes, which increases the clearance of LDL from the blood. **Analysis of Incorrect Options:** * **A & D. Resins / Bile Acid Sequestrants (e.g., Cholestyramine):** These are large, non-absorbable polymers that bind bile acids in the intestine, preventing their enterohepatic circulation. This forces the liver to use more cholesterol to synthesize new bile acids. * **C. Fibric Acid Derivatives (e.g., Fenofibrate, Gemfibrozil):** These act primarily by activating **PPAR-α (Peroxisome Proliferator-Activated Receptor-alpha)**, which increases the activity of lipoprotein lipase (LPL). They are the drugs of choice for reducing high triglyceride levels. **High-Yield NEET-PG Pearls:** * **Pleiotropic effects:** Statins have benefits beyond lipid-lowering, including plaque stabilization, anti-inflammatory effects, and improved endothelial function. * **Adverse Effects:** The most important side effects are **myopathy/rhabdomyolysis** (monitored via Creatine Kinase levels) and hepatotoxicity. * **Timing:** Most statins are given at night because hepatic cholesterol synthesis peaks between midnight and 2:00 AM. (Exception: Atorvastatin and Rosuvastatin have long half-lives and can be given anytime). * **Contraindication:** Statins are strictly **Teratogenic** (Category X).

Question 542: A 69-year-old woman is being treated for dysrhythmias with quinidine. Select the most likely side effects to occur.

A. Sensory loss
B. Prolonged QT interval (Correct Answer)
C. Parkinsonism-like symptoms
D. Action tremor

Explanation: **Explanation:** **Quinidine** is a prototype **Class IA antiarrhythmic** drug. Its primary mechanism of action involves blocking open sodium ($Na^+$) channels, but it also significantly blocks **delayed rectifier potassium ($K^+$) channels**. 1. **Why Option B is Correct:** By blocking potassium channels during phase 3 of the cardiac action potential, quinidine delays repolarization. This results in an **increase in the Action Potential Duration (APD)** and a **prolonged QT interval** on the ECG. A prolonged QT interval is a critical clinical concern as it predisposes patients to *Torsades de Pointes* (a polymorphic ventricular tachycardia). 2. **Why Other Options are Incorrect:** * **A & D (Sensory loss/Action tremor):** These are not associated with quinidine. While lidocaine (Class IB) can cause CNS toxicity (paresthesia/tremors), quinidine’s neurological profile is different. * **C (Parkinsonism):** This is typically caused by dopamine antagonists (e.g., antipsychotics or metoclopramide), not antiarrhythmics. **High-Yield Clinical Pearls for NEET-PG:** * **Cinchonism:** A classic triad of side effects unique to quinidine (and quinine) including tinnitus, dizziness, and headache. * **Vagolytic Effect:** Quinidine has antimuscarinic properties that can increase AV conduction; it is often co-administered with digoxin or a beta-blocker to prevent paradoxical tachycardia in atrial fibrillation. * **Drug Interaction:** Quinidine reduces the renal clearance of **Digoxin**, leading to digitalis toxicity. * **Diarrhea:** The most common gastrointestinal side effect (seen in ~30% of patients).

Question 543: Which of the following is not a calcium channel blocker?

A. Enalapril (Correct Answer)
B. Nifedipine
C. Diltiazem
D. Verapamil

Explanation: ### Explanation **Correct Option: A. Enalapril** **Why Enalapril is the correct answer:** Enalapril is not a Calcium Channel Blocker (CCB); it belongs to the class of **ACE Inhibitors (Angiotensin-Converting Enzyme Inhibitors)**. Its mechanism of action involves inhibiting the conversion of Angiotensin I to Angiotensin II (a potent vasoconstrictor) and preventing the breakdown of bradykinin. It is primarily used for hypertension, heart failure, and diabetic nephropathy. **Why the other options are incorrect:** The other three options are classic examples of Calcium Channel Blockers, which are categorized into two main groups [2]: * **Nifedipine (Option B):** A **Dihydropyridine (DHP)** [3]. These primarily act on vascular smooth muscle, causing peripheral vasodilation [1]. They are used for hypertension and angina. * **Diltiazem (Option C):** A **Benzothiazepine**. It is a non-DHP CCB with intermediate effects, acting on both the myocardium and blood vessels [1]. * **Verapamil (Option D):** A **Phenylalkylamine**. It is a non-DHP CCB that is relatively cardioselective [4]. It has significant negative inotropic and dromotropic effects, making it useful for supraventricular tachycardias (SVT) [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** Verapamil is a preferred drug for prophylaxis of cluster headaches and controlling rate in SVT. * **Side Effects:** A common side effect of Nifedipine/Amlodipine is **ankle edema**, while Verapamil is notorious for causing **constipation**. * **Contraindication:** Non-DHP CCBs (Verapamil, Diltiazem) should be avoided in patients with Heart Failure with reduced Ejection Fraction (HFrEF) and AV blocks. * **ACEI Hallmark:** The most common side effect of Enalapril is a **dry cough**, mediated by increased bradykinin levels.

Question 544: Which drug has a positive effect on the lipid profile?

A. Atenolol
B. Hydrochlorothiazide
C. Furosemide
D. Prazosin (Correct Answer)

Explanation: **Explanation:** The correct answer is **Prazosin**. **1. Why Prazosin is correct:** Prazosin is a selective **alpha-1 (α1) adrenergic blocker**. Unlike many other antihypertensives, alpha-blockers have a favorable or "positive" effect on the lipid profile. They decrease total cholesterol, LDL (low-density lipoprotein), and triglycerides while simultaneously increasing HDL (high-density lipoprotein) levels. Additionally, they improve insulin sensitivity, making them a preferred choice for hypertensive patients with comorbid dyslipidemia or diabetes mellitus. **2. Why the other options are incorrect:** * **Atenolol (Beta-blocker):** Non-selective and cardioselective beta-blockers (like Atenolol) generally have a negative impact on lipids. They tend to increase triglycerides and decrease "good" HDL cholesterol. * **Hydrochlorothiazide (Thiazide Diuretic):** Thiazides are notorious for metabolic side effects. They can cause **hyperlipidemia** (elevated LDL and triglycerides), hyperuricemia, and hyperglycemia. * **Furosemide (Loop Diuretic):** Similar to thiazides, loop diuretics can cause transient increases in plasma cholesterol and triglyceride levels, though their effect is generally less pronounced than thiazides. **3. Clinical Pearls for NEET-PG:** * **Metabolic Neutrality:** ACE inhibitors, ARBs, and Calcium Channel Blockers (CCBs) are considered **metabolically neutral** (they do not significantly affect lipids or glucose). * **First-Dose Phenomenon:** Always warn patients about postural hypotension with Prazosin; it should be taken at bedtime. * **BPH:** Alpha-blockers are also used to treat Benign Prostatic Hyperplasia as they relax the smooth muscles of the bladder neck and prostate.

Question 545: What is the mechanism of statin action on HMG CoA reductase?

A. Competitive inhibitor (Correct Answer)
B. Irreversible inhibitor
C. Non-competitive inhibitor
D. Inhibition results in decreased LDL receptors on hepatocytes

Explanation: ### Explanation **1. Why Option A is Correct:** Statins (e.g., Atorvastatin, Rosuvastatin) are structural analogs of **3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA)**. Because they resemble the natural substrate, they bind to the active site of the enzyme **HMG-CoA reductase**, the rate-limiting enzyme in cholesterol synthesis. This is a classic example of **reversible competitive inhibition**. By blocking this enzyme, statins prevent the conversion of HMG-CoA to mevalonate, thereby reducing endogenous cholesterol production. **2. Why the Other Options are Incorrect:** * **Option B (Irreversible inhibitor):** Statins bind reversibly. Their inhibitory effect can be overcome by increasing the concentration of the substrate (HMG-CoA), which is a hallmark of competitive inhibition. * **Option C (Non-competitive inhibitor):** Non-competitive inhibitors bind to an allosteric site, not the active site. Statins specifically compete for the active catalytic site of the enzyme. * **Option D (Decreased LDL receptors):** This is factually reversed. The decrease in intracellular cholesterol triggers a compensatory **upregulation (increase)** of LDL receptors on the hepatocyte surface. These receptors pull LDL from the blood, which is the primary mechanism by which statins lower plasma LDL levels. **3. High-Yield Clinical Pearls for NEET-PG:** * **Pleiotropic Effects:** Beyond lowering lipids, statins stabilize atherosclerotic plaques, improve endothelial function, and have anti-inflammatory properties. * **Side Effects:** The most common "high-yield" side effects are **myopathy/rhabdomyolysis** (monitored via Creatine Kinase levels) and **hepatotoxicity** (monitored via LFTs). * **Timing:** Statins with short half-lives (e.g., Simvastatin, Lovastatin) should be taken at **night**, as peak cholesterol synthesis occurs during sleep. * **Contraindication:** Statins are strictly **Teratogenic** (Category X).

Question 546: Which of the following drugs is most likely to precipitate angina?

A. Diltiazem
B. Verapamil
C. Amlodipine
D. Nifedipine (Correct Answer)

Explanation: ### Explanation The correct answer is **Nifedipine**. **1. Why Nifedipine precipitates angina:** Nifedipine is a short-acting **Dihydropyridine (DHP)** Calcium Channel Blocker (CCB). It is a potent peripheral vasodilator. When administered (especially in its immediate-release form), it causes a rapid drop in blood pressure, which triggers a powerful **reflex sympathetic activation**. This leads to **reflex tachycardia** and increased myocardial contractility. These two factors significantly increase myocardial oxygen demand. In patients with pre-existing coronary artery disease, this sudden surge in oxygen demand can outpace the supply, thereby precipitating or worsening angina (and in some cases, myocardial infarction). **2. Why the other options are incorrect:** * **Verapamil and Diltiazem (Non-DHPs):** These drugs have significant direct depressant effects on the SA and AV nodes (negative chronotropic and dromotropic effects). Because they slow the heart rate and decrease contractility, they do not cause reflex tachycardia. In fact, they are used in the *treatment* of chronic stable angina. * **Amlodipine (Long-acting DHP):** While amlodipine is a DHP like nifedipine, it has a very slow onset of action and a long half-life. This results in a gradual modification of blood pressure without the sharp sympathetic surge or significant reflex tachycardia seen with short-acting nifedipine. **3. NEET-PG High-Yield Pearls:** * **The "Steal" Phenomenon:** Potent vasodilators can sometimes divert blood away from ischemic areas to non-ischemic areas, further worsening angina. * **Clinical Contraindication:** Immediate-release nifedipine is contraindicated in the management of hypertensive emergencies and acute coronary syndromes due to the risk of reflex tachycardia and stroke. * **Preferred DHP:** If a DHP must be used in angina, long-acting agents like **Amlodipine** or extended-release formulations are preferred. * **Drug of Choice:** For **Prinzmetal (variant) angina**, CCBs (like Nifedipine or Diltiazem) are the drugs of choice as they relieve coronary vasospasm.

Question 547: Which of the following statins can be administered at any time of the day?

A. Lovastatin
B. Simvastatin
C. Pravastatin
D. Atorvastatin (Correct Answer)

Explanation: ### Explanation **Concept:** Statins (HMG-CoA reductase inhibitors) inhibit the rate-limiting step of cholesterol synthesis. Endogenous cholesterol synthesis primarily occurs at night during sleep. Therefore, statins with a **short half-life** must be administered at bedtime to ensure peak plasma concentrations coincide with peak cholesterol synthesis. Statins with a **long half-life** provide sustained inhibition and can be taken at any time of the day. **Why Atorvastatin is Correct:** * **Atorvastatin** (and **Rosuvastatin**) has a long elimination half-life (approx. 14–20 hours). * Its active metabolites also contribute to its prolonged effect (up to 20–30 hours). * Because of this extended duration of action, its efficacy in lowering LDL-C is independent of the time of administration. **Why Other Options are Incorrect:** * **A. Lovastatin:** Has a short half-life (~2 hours) and is most effective when taken with the evening meal (food increases its absorption). * **B. Simvastatin:** Has a short half-life (~2–3 hours) and must be taken at bedtime. * **C. Pravastatin:** Has a short half-life (~1.5–3 hours) and is recommended for evening administration. **High-Yield Clinical Pearls for NEET-PG:** * **Long-acting statins:** Atorvastatin, Rosuvastatin, and Pitavastatin (can be taken anytime). * **Prodrug statins:** Lovastatin and Simvastatin (administered as inactive lactones). * **Most Potent Statin:** Rosuvastatin. * **Water-soluble (Hydrophilic) Statins:** Pravastatin and Rosuvastatin (lower risk of myopathy as they do not easily penetrate peripheral tissues). * **Metabolism:** Most statins are metabolized by **CYP3A4** (except Pravastatin and Rosuvastatin), making them prone to drug interactions with inhibitors like macrolides or grapefruit juice.

Question 548: Which of the following statements regarding ACE inhibitors is true?

A. Inhibits conversion of angiotensinogen to angiotensin I
B. The half-life of enalapril is longer than lisinopril
C. Omitting a prior diuretic dose decreases the risk of postural hypotension (Correct Answer)
D. It is effective only in the presence of left ventricular systolic dysfunction

Explanation: **Explanation:** **Why Option C is Correct:** The most significant adverse effect of the first dose of an ACE inhibitor (ACEi) is **"First-dose hypotension."** This occurs because ACE inhibitors cause a rapid fall in Angiotensin II levels. Patients on diuretics are often volume-depleted and have a highly activated Renin-Angiotensin-Aldosterone System (RAAS). In such patients, the sudden blockade of the RAAS leads to a precipitous drop in blood pressure. **Omitting the diuretic dose 24 hours prior** to starting an ACEi reduces this risk by allowing partial volume restoration and decreasing RAAS dependency. **Analysis of Incorrect Options:** * **Option A:** ACE inhibitors inhibit the **Angiotensin-Converting Enzyme**, which converts Angiotensin I to Angiotensin II. The conversion of Angiotensinogen to Angiotensin I is inhibited by **Aliskiren** (a direct renin inhibitor). * **Option B:** **Lisinopril** has a longer half-life (~12 hours) compared to **Enalapril** (~11 hours, though its active metabolite enalaprilat is the functional component). More importantly, Lisinopril is a lysine-analog and is one of the few ACEis that is **not a prodrug**. * **Option D:** While ACEis are the gold standard for LV systolic dysfunction, they are also first-line agents for **hypertension, diabetic nephropathy** (due to efferent arteriolar dilation), and prophylaxis in high-risk cardiovascular patients, regardless of LV function. **High-Yield Clinical Pearls for NEET-PG:** * **Teratogenicity:** ACEis are contraindicated in pregnancy (cause fetal renal anomalies and oligohydramnios). * **Metabolism:** All ACEis are prodrugs except **Lisinopril and Captopril**. * **Side Effects:** Dry cough (due to Bradykinin accumulation) and Angioedema are classic associations. * **Electrolytes:** They cause **Hyperkalemia** (due to decreased Aldosterone). Avoid concomitant use with potassium-sparing diuretics.

Question 549: Digoxin is not indicated in which of the following conditions?

A. Atrial flutter
B. Atrial fibrillation
C. High output failure (Correct Answer)
D. Paroxysmal supraventricular tachycardia (PSVT)

Explanation: ### Explanation **Correct Option: C. High output failure** **Why it is the correct answer:** Digoxin is a cardiac glycoside that acts by inhibiting the **Na+/K+-ATPase pump**, leading to increased intracellular calcium and positive inotropy. It is primarily used to improve contractility in systolic heart failure and to control ventricular rate in supraventricular arrhythmias. However, **High Output Failure** (caused by conditions like anemia, thyrotoxicosis, beriberi, or AV fistulas) is not a primary pump failure. In these cases, the heart is already working at a high capacity to meet excessive metabolic demands. Digoxin is ineffective here because the underlying pathology is peripheral vasodilation or increased metabolic rate, not a deficit in myocardial contractility. Treating the underlying cause is the mainstay of management. **Why the other options are incorrect:** * **Atrial Fibrillation (B) and Atrial Flutter (A):** Digoxin is indicated for **rate control**. It increases vagal tone, which decreases conduction velocity through the AV node, thereby protecting the ventricles from the rapid atrial rate. * **PSVT (D):** While not the first-line treatment (Adenosine is preferred), Digoxin can be used for prophylaxis or treatment of PSVT due to its vagomimetic effects on the AV node, which can terminate the re-entrant circuit. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Positive Inotrope (inhibits Na+/K+ ATPase) and Negative Chronotrope (increases vagal tone). * **ECG Changes:** Characteristically shows a **"Reverse Tick" sign** or "Sagging" ST-segment depression. * **Toxicity:** Hypokalemia predisposes to Digoxin toxicity. The most common arrhythmia in toxicity is **PVCs**, while the most characteristic is **Non-paroxysmal atrial tachycardia with AV block**. * **Contraindications:** WPW syndrome, Hypertrophic Obstructive Cardiomyopathy (HOCM), and Ventricular Tachycardia.

Question 550: Which of the following medications is NOT used in the treatment of congestive heart failure?

A. Hydralazine
B. Nifedipine
C. Prazosin
D. Nitrates (Correct Answer)

Explanation: **Explanation:** The management of Congestive Heart Failure (CHF) focuses on reducing preload and afterload to improve cardiac output. While many vasodilators are beneficial, certain classes are avoided due to their hemodynamic effects. **Why Nitrates is the correct answer (in the context of this specific question):** *Note: There is a clinical nuance here.* While Nitrates (venodilators) are used in acute heart failure to reduce preload, they are rarely used as **monotherapy** for chronic CHF. However, in the context of standard NEET-PG patterns, **Nifedipine** is traditionally the drug avoided in CHF. If the provided key marks Nitrates as the answer, it refers to the fact that nitrates alone do not provide a survival benefit and can lead to tachyphylaxis (tolerance). **Analysis of Options:** * **Hydralazine (A):** An arterial vasodilator that reduces afterload. When combined with Isosorbide Dinitrate (BiDil), it is proven to reduce mortality in CHF, especially in African-American patients. * **Nifedipine (B):** A short-acting Dihydropyridine Calcium Channel Blocker (CCB). It is generally **avoided** in CHF because it can cause reflex tachycardia and has negative inotropic effects which may worsen heart failure. * **Prazosin (C):** An alpha-1 blocker that provides balanced vasodilation (arteries and veins). While not a first-line agent like ACE inhibitors, it can be used to reduce both preload and afterload. **High-Yield Clinical Pearls for NEET-PG:** 1. **Drugs that improve survival in CHF:** ACE inhibitors, ARBs, Beta-blockers (Carvedilol, Metoprolol succinate, Bisoprolol), Spironolactone, and Hydralazine + Nitrate combination. 2. **Drugs to avoid in CHF:** Most CCBs (except Amlodipine/Felodipine if needed for HTN), NSAIDs (cause salt/water retention), and Anti-arrhythmics (Class I and sotalol). 3. **Sacubitril/Valsartan (ARNI):** Currently the preferred agent over ACE inhibitors for symptomatic HFrEF.

Practice by Chapter

Antihypertensive Agents

Practice Questions

Drugs for Heart Failure

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Antiarrhythmic Drugs

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Antianginal Agents

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Lipid-Lowering Drugs

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Anticoagulants and Antiplatelet Drugs

Practice Questions

Thrombolytic Agents

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Drugs Used in Pulmonary Hypertension

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Drugs Used in Shock

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Cardiovascular Effects of Non-Cardiovascular Drugs

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