Cardiovascular Drugs — MCQs

Cardiovascular Drugs Indian Medical PG Practice Questions and MCQs

Question 371: Which of the following potassium channel openers has antianginal activity?

A. Nicorandil (Correct Answer)
B. Dipyridamole
C. Trimetazidine
D. Oxyphedrine

Explanation: **Explanation:** **Nicorandil** is the correct answer because it possesses a unique dual mechanism of action. It acts as both a **Potassium (K⁺) channel opener** and a **Nitrate-like vasodilator**. By opening ATP-sensitive K⁺ channels in vascular smooth muscle, it causes K⁺ efflux, leading to hyperpolarization and subsequent vasodilation of the arterioles (reducing afterload). Simultaneously, its nitrate moiety increases cGMP levels, leading to venous dilation (reducing preload). This dual action improves coronary blood flow and reduces myocardial oxygen demand, making it effective in treating stable angina. **Analysis of Incorrect Options:** * **B. Dipyridamole:** This is a phosphodiesterase inhibitor and adenosine reuptake inhibitor. While it is a vasodilator, it is notorious for causing **"Coronary Steal Phenomenon,"** where it diverts blood away from ischemic areas to non-ischemic areas, making it unsuitable for acute angina. * **C. Trimetazidine:** This is a **metabolic modulator** (p-FOX inhibitor). It shifts myocardial metabolism from fatty acid oxidation to glucose oxidation, which requires less oxygen. It does not act on potassium channels. * **D. Oxyphedrine:** This is a partial beta-agonist that improves myocardial metabolism and coronary flow, but it is not a potassium channel opener. **High-Yield Pearls for NEET-PG:** * **Nicorandil Side Effect:** A highly characteristic side effect is **painful mucosal ulcerations** (oral, anal, or perianal ulcers). * **K⁺ Channel Openers:** Other drugs in this class include Minoxidil and Diazoxide (used for hypertension/hypoglycemia), but Nicorandil is the primary one used for angina. * **Preconditioning:** Nicorandil mimics "ischemic preconditioning," providing a cardioprotective effect during episodes of ischemia.

Question 372: Which of the following statements is not true regarding dobutamine?

A. Agonist of D1 and D2 receptors (Correct Answer)
B. Derivative of dopamine
C. Selective beta-agonistic action
D. Reduced chances of arrhythmia than adrenaline

Explanation: ### Explanation **Dobutamine** is a synthetic catecholamine used primarily in the management of acute heart failure and cardiogenic shock. **1. Why Option A is the Correct Answer (The "Not True" Statement):** Unlike its parent compound dopamine, **dobutamine does not act on dopaminergic (D1 and D2) receptors.** It does not cause renal vasodilation or modulate prolactin release via dopaminergic pathways. This is a high-yield distinction often tested in exams to differentiate it from dopamine. **2. Analysis of Incorrect Options:** * **Option B (Derivative of dopamine):** This is **true**. Dobutamine is chemically synthesized by substituting the side chain of dopamine. * **Option C (Selective beta-agonistic action):** This is **true**. While it has some $\alpha_1$ activity, its predominant clinical effect is mediated through **$\beta_1$ receptors** (increasing contractility) and some $\beta_2$ activity (mild vasodilation). It is often referred to as an "inodilator." * **Option D (Reduced chances of arrhythmia than adrenaline):** This is **true**. Dobutamine is relatively less arrhythmogenic compared to adrenaline or isoproterenol because it increases myocardial contractility (inotropy) more significantly than it increases the heart rate (chronotropy). ### NEET-PG High-Yield Pearls * **Drug of Choice:** Dobutamine is the drug of choice for **cardiogenic shock** (when BP is stable) and **stress echocardiography** to detect viable myocardium. * **Receptor Profile:** Predominantly $\beta_1 > \beta_2 > \alpha_1$. * **Hemodynamic Effect:** It increases Cardiac Output (CO) while decreasing Systemic Vascular Resistance (SVR) and Pulmonary Capillary Wedge Pressure (PCWP). * **Half-life:** Very short (~2 minutes), requiring continuous IV infusion.

Question 373: Which of the following is NOT an extracardiac manifestation of Quinidine?

A. Diarrhea
B. Congestive cardiac failure (Correct Answer)
C. Cinchonism
D. Thrombocytopenia

Explanation: **Explanation:** The question asks for the **extracardiac** manifestation that is *not* associated with Quinidine. **1. Why Congestive Cardiac Failure (CCF) is the correct answer:** Quinidine is a Class IA antiarrhythmic agent. While it can cause cardiac side effects such as QT prolongation, Torsades de Pointes (Quinidine syncope), and negative inotropic effects, **Congestive Cardiac Failure is classified as a cardiac manifestation**, not an extracardiac one. Therefore, it does not fit the criteria of the question. **2. Analysis of Extracardiac Manifestations (Incorrect Options):** * **Diarrhea:** This is the most common extracardiac side effect of Quinidine, occurring in approximately 30-50% of patients due to its local irritant effect on the GI tract. * **Cinchonism:** A classic triad of symptoms (tinnitus, headache, and visual disturbances/dizziness) resulting from toxicity. Since Quinidine is a cinchona alkaloid, this is a pathognomonic extracardiac side effect. * **Thrombocytopenia:** Quinidine can induce an immune-mediated destruction of platelets (Type II hypersensitivity), leading to petechiae and bleeding. **Clinical Pearls for NEET-PG:** * **Mechanism:** Blocks fast sodium channels (Phase 0) and potassium channels (Phase 3), leading to increased Action Potential Duration (APD) and Effective Refractory Period (ERP). * **Vagolytic Effect:** Quinidine has anticholinergic properties that can increase AV conduction; hence, it should be preceded by a beta-blocker or CCB when treating atrial flutter/fibrillation. * **Drug Interaction:** It significantly increases **Digoxin levels** by displacing it from tissue binding sites and reducing its renal clearance.

Question 374: Which antihypertensive agent cannot be given during pregnancy?

A. Labetalol
B. Propranolol (Correct Answer)
C. Esmolol
D. Hydralazine

Explanation: The management of hypertension in pregnancy requires drugs that maintain placental perfusion while avoiding teratogenicity or fetal growth restriction. **Why Propranolol is the Correct Answer:** While not strictly "contraindicated" in the same category as ACE inhibitors or ARBs, **Propranolol** is generally avoided in pregnancy. As a non-selective beta-blocker, it is associated with **Intrauterine Growth Restriction (IUGR)**, neonatal hypoglycemia, and fetal bradycardia. It can also increase uterine tone by blocking {2} receptors, potentially leading to premature labor. Among the options provided, it is the least preferred agent for long-term management. **Analysis of Incorrect Options:** * **Labetalol (Option A):** This is the **drug of choice (DOC)** for chronic hypertension in pregnancy. Its combined and blocking activity maintains peripheral blood flow without causing significant reflex tachycardia or reducing placental perfusion. * **Esmolol (Option B):** An ultra-short-acting {1} blocker used primarily for hypertensive emergencies or intraoperative tachycardia. While not a first-line maintenance drug, it is not contraindicated for acute settings. * **Hydralazine (Option D):** A direct vasodilator that is a classic choice for the management of **Hypertensive Emergencies** in pregnancy (e.g., severe pre-eclampsia) [1]. **NEET-PG High-Yield Pearls:** * **Safe Antihypertensives in Pregnancy:** "Better Mother Care During Labor" — **B**eta-blockers (Labetalol), **M**ethyldopa (traditional DOC) [2], **C**alcium Channel Blockers (Nifedipine), **D**irect Vasodilators (Hydralazine). * **Absolutely Contraindicated:** ACE inhibitors and ARBs (cause fetal renal dysgenesis, oligohydramnios, and skull defects) [3]. * **Methyldopa** is the safest long-term drug but is often replaced by Labetalol due to a better side-effect profile.

Question 375: What are the effects of beta-blockers on the heart, except for which of the following?

A. Decrease in heart rate
B. Decreases duration of systole (Correct Answer)
C. Decreases cardiac output
D. Precipitates heart failure

Explanation: ### Explanation **Core Concept: Beta-Blockers and Cardiac Hemodynamics** Beta-blockers (e.g., Propranolol, Metoprolol) act by antagonizing $\beta_1$-adrenergic receptors in the heart. This leads to negative inotropic (force), chronotropic (rate), dromotropic (conduction), and lusitropic (relaxation) effects. **Why Option B is Correct:** Beta-blockers **increase**, rather than decrease, the duration of the cardiac cycle, primarily by **prolonging diastole**. By slowing the heart rate (negative chronotropy), the time available for ventricular filling (diastole) is significantly lengthened. The duration of systole remains relatively constant or may slightly increase due to the negative inotropic effect, but it is never "decreased" as a primary pharmacological action. **Analysis of Incorrect Options:** * **A. Decrease in heart rate:** This is the hallmark effect of beta-blockers due to the blockade of $\beta_1$ receptors in the SA node. * **C. Decreases cardiac output:** Since Cardiac Output = Stroke Volume × Heart Rate, the reduction in both contractility and heart rate leads to a decrease in overall cardiac output. * **D. Precipitates heart failure:** In patients with compensated heart failure or borderline cardiac reserve, the negative inotropic effect can acutely worsen the condition and precipitate acute decompensated heart failure. **High-Yield Clinical Pearls for NEET-PG:** * **Diastolic Filling:** The prolongation of diastole is beneficial in **Mitral Stenosis** (allows more time for blood to flow into the LV) and **Angina** (improves coronary perfusion, which occurs during diastole). * **Reverse Remodeling:** While they can precipitate acute failure, long-term use of specific beta-blockers (**Metoprolol, Bisoprolol, Carvedilol**) reduces mortality in chronic heart failure. * **Contraindication:** Avoid in Prinzmetal angina (may cause unopposed alpha-mediated vasoconstriction).

Question 376: An elderly patient on beta-blocker therapy is prone to develop which of the following complications?

A. Asthma
B. Congestive Heart Failure (CHF)
C. Bradycardia
D. All of the above (Correct Answer)

Explanation: Beta-blockers act by antagonizing $eta_1$ and $eta_2$ adrenergic receptors, leading to physiological changes that can precipitate specific complications, especially in the elderly [1], [2]. 1. **Bradycardia:** This is a direct consequence of $eta_1$ blockade at the SA and AV nodes. It reduces the heart rate (negative chronotropic effect) and slows conduction. In elderly patients with pre-existing conduction system disease, this can lead to symptomatic bradycardia or heart block [2], [3]. 2. **Congestive Heart Failure (CHF):** Beta-blockers exert a negative inotropic effect (reduced contractility). In patients with compensated heart failure or borderline cardiac reserve, the sudden withdrawal of sympathetic drive can lead to acute decompensation and pulmonary edema [1], [2]. 3. **Asthma:** Non-selective beta-blockers (like Propranolol) block $eta_2$ receptors in the bronchial smooth muscle, leading to bronchoconstriction. This can trigger life-threatening bronchospasm in patients with asthma or COPD [1], [3]. **Why "All of the above" is correct:** Since beta-blockers affect the heart (nodes and myocardium) and the lungs simultaneously, all three conditions are recognized adverse effects and contraindications in susceptible individuals [1], [2], [3]. **High-Yield Clinical Pearls for NEET-PG:** * **Cardioselectivity:** $eta_1$-selective blockers (e.g., **M**etoprolol, **A**tenolol, **B**isoprolol, **E**smolol—mnemonic: **MABE**) are safer in asthmatics but should still be used with caution [1]. * **Diabetes:** Beta-blockers can mask the tachycardia associated with hypoglycemia, making it dangerous for diabetic patients [2]. * **Peripheral Vascular Disease:** They can worsen Raynaud's phenomenon due to unopposed $\alpha$-mediated vasoconstriction [1]. * **Lipid Profile:** They may increase triglycerides and decrease HDL levels (except those with ISA like Pindolol).

Question 377: Which one of the following best represents the mechanism of action and electrocardiographic effect of diltiazem?

A. Calcium channel blockade; increased QT interval
B. Adrenergic receptor blockade; decreased QT interval
C. Calcium channel blockade; increased PR interval (Correct Answer)
D. Potassium channel blockade; increased QRS duration

Explanation: **Mechanism of Action and ECG Effects of Diltiazem** **Correct Answer: C. Calcium channel blockade; increased PR interval** **Explanation:** Diltiazem is a **Non-dihydropyridine Calcium Channel Blocker (CCB)**. It primarily acts by blocking L-type calcium channels in the myocardium and the cardiac conduction system (SA and AV nodes). 1. **Mechanism:** By inhibiting the inward flow of calcium during the action potential, diltiazem slows the rate of recovery of the calcium channels. 2. **ECG Effect:** Its most significant effect is on the **Atrioventricular (AV) node**, where it decreases conduction velocity and increases the refractory period. On an ECG, AV nodal delay is represented by an **increased PR interval**. **Analysis of Incorrect Options:** * **A & B (QT Interval):** The QT interval represents ventricular repolarization, primarily governed by potassium channels. Drugs like Class IA and Class III antiarrhythmics (e.g., Amiodarone) increase the QT interval. Diltiazem has a negligible effect on the QT interval. * **B (Adrenergic Blockade):** This is the mechanism of Beta-blockers. While both Beta-blockers and Diltiazem increase the PR interval, Diltiazem’s primary molecular target is the calcium channel. * **D (QRS Duration):** The QRS complex represents ventricular depolarization (sodium channel mediated). Sodium channel blockers (Class I antiarrhythmics like Flecainide) increase QRS duration. **NEET-PG High-Yield Pearls:** * **Classification:** Diltiazem (Benzothiazepine) and Verapamil (Phenylalkylamine) are Class IV antiarrhythmics. * **Clinical Use:** Preferred for **rate control** in Atrial Fibrillation and Paroxysmal Supraventricular Tachycardia (PSVT). * **Contraindication:** Avoid in patients with Heart Failure with reduced Ejection Fraction (HFrEF) due to negative inotropic effects, and in Wolff-Parkinson-White (WPW) syndrome with AF. * **Side Effect:** Gingival hyperplasia (common to all CCBs) and constipation (more common with Verapamil).

Question 378: Which potent antiarrhythmic drug has little negative inotropic effect, making it valuable in patients with poor left ventricular function?

A. Amlodipine
B. Bidoprolo
C. Amiodarone
D. Digoxin (Correct Answer)

Explanation: **Explanation** The correct answer is **Digoxin**. **Why Digoxin is correct:** Digoxin is a cardiac glycoside that inhibits the **Na+/K+-ATPase pump**, leading to an increase in intracellular calcium. This results in a **positive inotropic effect** (increased force of contraction), which is highly beneficial in patients with heart failure or poor left ventricular (LV) function. Simultaneously, it exerts a potent **antiarrhythmic effect** (specifically for supraventricular arrhythmias like Atrial Fibrillation) by increasing vagal tone, which slows conduction through the AV node. Unlike most other antiarrhythmics, it does not depress myocardial contractility. **Why the other options are incorrect:** * **Amlodipine:** This is a dihydropyridine Calcium Channel Blocker (CCB). While it has minimal negative inotropic effects, it is primarily an **antihypertensive/anti-anginal** drug and is not used as an antiarrhythmic. * **Bisoprolol:** As a Beta-blocker, it has significant **negative inotropic** effects. While used in chronic heart failure, it must be started cautiously as it can acutely worsen compensation in patients with severely depressed LV function. * **Amiodarone:** Although it is a potent antiarrhythmic often used in heart failure, it can still exert mild negative inotropic effects (especially when given IV). Digoxin is the more classic answer for a drug that specifically *increases* or maintains contractility while treating arrhythmias. **High-Yield NEET-PG Pearls:** * **Mechanism:** Digoxin increases vagal tone (parasympathomimetic), making it the drug of choice for controlling ventricular rate in **Atrial Fibrillation with Heart Failure**. * **Toxicity:** The earliest sign of Digoxin toxicity is **anorexia/nausea**. The most characteristic ECG finding is the **"Reverse Tick" sign** (ST-segment depression). * **Electrolytes:** **Hypokalemia** predisposes a patient to Digoxin toxicity because K+ and Digoxin compete for the same binding site on the Na+/K+-ATPase pump.

Question 379: Abciximab is:

A. Antibody against IIb/IIIa receptors (Correct Answer)
B. Antibody against Ib/IX receptors
C. Topoisomerase inhibitor
D. Adenosine inhibitor

Explanation: **Explanation:** **Abciximab** is a potent antiplatelet agent classified as a **Glycoprotein (GP) IIb/IIIa receptor antagonist**. 1. **Why Option A is Correct:** Abciximab is the Fab fragment of a chimeric human-murine monoclonal antibody. It binds irreversibly to the GP IIb/IIIa receptors on the surface of activated platelets. Since these receptors are the "final common pathway" for platelet aggregation (by binding fibrinogen to cross-link platelets), inhibiting them prevents thrombus formation regardless of the initial stimulus (ADP, Thromboxane A2, or Thrombin). 2. **Why Other Options are Incorrect:** * **Option B:** Receptors Ib/IX are involved in platelet *adhesion* to von Willebrand factor (vWF), not aggregation. No major clinical drug currently targets this specifically in this manner. * **Option C:** Topoisomerase inhibitors (e.g., Etoposide, Irinotecan) are cytotoxic chemotherapy agents used in cancer treatment, not cardiovascular medicine. * **Option D:** Adenosine inhibitors (like Theophylline) or Adenosine uptake inhibitors (like Dipyridamole) have different mechanisms. Dipyridamole is an antiplatelet drug, but it works via PDE inhibition, not as an antibody. **NEET-PG High-Yield Pearls:** * **Route:** Administered only via **Intravenous (IV)** route. * **Clinical Use:** Primarily used in **Percutaneous Coronary Intervention (PCI)** to prevent ischemic complications and in Unstable Angina/NSTEMI. * **Other GP IIb/IIIa Inhibitors:** **Eptifibatide** (cyclic peptide) and **Tirofiban** (non-peptide small molecule). Unlike Abciximab, these are reversible inhibitors. * **Major Side Effect:** Bleeding and **Thrombocytopenia** (monitor platelet counts).

Question 380: The first dose effect is commonly seen with which of the following medications?

A. Prazosin (Correct Answer)
B. Guanethidine
C. Propranolol
D. Clonidine

Explanation: ### Explanation **Correct Option: A. Prazosin** The **"First-Dose Effect"** is a classic pharmacological phenomenon characterized by a sudden, severe episode of orthostatic hypotension and syncope occurring within 30–90 minutes of the initial dose of a drug. It is most characteristically associated with **selective alpha-1 blockers** like Prazosin. **Mechanism:** Alpha-1 receptors normally maintain vascular tone. Rapid blockade leads to profound peripheral vasodilation and venous pooling. When the patient stands, the compensatory baroreceptor reflex is insufficient to maintain cerebral perfusion, leading to syncope. **Why other options are incorrect:** * **B. Guanethidine:** This is a post-ganglionic adrenergic neuron blocker. While it causes postural hypotension as a chronic side effect, it does not typically manifest as the acute, dramatic "first-dose" syncopal phenomenon seen with Prazosin. * **C. Propranolol:** As a non-selective beta-blocker, it reduces heart rate and cardiac output. It does not cause acute vasodilation; in fact, it may cause transient peripheral vasoconstriction due to unopposed alpha activity. * **D. Clonidine:** An alpha-2 agonist that reduces sympathetic outflow. Its primary concern is **rebound hypertension** upon sudden withdrawal, rather than first-dose hypotension. **High-Yield Clinical Pearls for NEET-PG:** * **Prevention:** To minimize the first-dose effect, the initial dose should be small (e.g., 1 mg) and administered **at bedtime** ("Start low, go slow, and give at night"). * **Other drugs:** Doxazosin and Terazosin also cause this effect, though it is most severe with Prazosin. * **Drug Interactions:** The risk of first-dose syncope is significantly increased if the patient is already taking diuretics or other antihypertensives.

Practice by Chapter

Antihypertensive Agents

Practice Questions

Drugs for Heart Failure

Practice Questions

Antiarrhythmic Drugs

Practice Questions

Antianginal Agents

Practice Questions

Lipid-Lowering Drugs

Practice Questions

Anticoagulants and Antiplatelet Drugs

Practice Questions

Thrombolytic Agents

Practice Questions

Drugs Used in Pulmonary Hypertension

Practice Questions

Drugs Used in Shock

Practice Questions

Cardiovascular Effects of Non-Cardiovascular Drugs

Practice Questions

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