Cardiovascular Drugs — MCQs

Cardiovascular Drugs Indian Medical PG Practice Questions and MCQs

Question 81: Which drug possesses beta-adrenergic blocking, antioxidant, calcium channel blocking, and alpha-1 antagonist activities?

A. Esmolol
B. Carvedilol (Correct Answer)
C. Nebivolol
D. Levobunolol

Explanation: **Explanation:** **Carvedilol** is a unique, non-selective third-generation beta-blocker. Its multifaceted pharmacological profile makes it the correct answer: * **Beta-Blocking:** It blocks both $\beta_1$ and $\beta_2$ receptors. * **Alpha-1 Antagonism:** It provides peripheral vasodilation by blocking $\alpha_1$ receptors, which reduces afterload. * **Antioxidant Activity:** It possesses carbazole rings that scavenge free radicals, preventing lipid peroxidation and protecting the myocardium from oxidative stress. * **Calcium Channel Blocking:** At higher concentrations, it exhibits membrane-stabilizing activity and weak L-type calcium channel blockade. **Analysis of Incorrect Options:** * **A. Esmolol:** An ultra-short-acting, cardioselective ($\beta_1$) blocker. It lacks alpha-blocking or antioxidant properties and is primarily used for acute arrhythmia or intraoperative hypertension. * **C. Nebivolol:** A highly selective $\beta_1$ blocker. While it causes vasodilation, it does so via **Nitric Oxide (NO) release**, not $\alpha_1$ blockade. It does not have significant calcium channel blocking activity. * **D. Levobunolol:** A non-selective beta-blocker used topically in the eye for glaucoma. It lacks the ancillary vasodilator and antioxidant properties of carvedilol. **High-Yield Clinical Pearls for NEET-PG:** * **Heart Failure:** Carvedilol is a "gold standard" beta-blocker (along with Metoprolol succinate and Bisoprolol) proven to reduce mortality in Chronic Heart Failure (CHF). * **Lipid Neutrality:** Unlike first-generation beta-blockers, carvedilol does not adversely affect lipid profiles or insulin sensitivity due to its $\alpha_1$ blocking effect. * **Metabolism:** It is highly lipophilic and undergoes extensive hepatic metabolism.

Question 82: Which one of the following is the most characteristic arrhythmia associated with digitalis toxicity?

A. Atrial fibrillation
B. Extrasystoles
C. Non-paroxysmal atrial tachycardia with block (Correct Answer)
D. Auricular flutter

Explanation: ### Explanation **Correct Answer: C. Non-paroxysmal atrial tachycardia with block** Digitalis (Digoxin) toxicity is a high-yield topic in NEET-PG due to its narrow therapeutic index. The most **characteristic** (pathognomonic) arrhythmia is **Non-paroxysmal atrial tachycardia with 2:1 AV block** [2]. **Mechanism:** Digitalis toxicity increases automaticity (causing tachycardia) while simultaneously depressing AV node conduction (causing block) [1]. This unique combination occurs because Digoxin inhibits the Na+/K+ ATPase pump, leading to increased intracellular calcium (triggering ectopic beats) and increased vagal tone (slowing the AV node) [1]. **Analysis of Options:** * **Extrasystoles (Option B):** While **Ventricular Bigeminy** (extrasystoles) is the **most common** arrhythmia seen in digitalis toxicity, it is not the most *characteristic* [1]. In exams, "most common" and "most characteristic" are distinct terms. * **Atrial Fibrillation (Option A) and Auricular Flutter (Option D):** These are clinical indications for using Digoxin (to control ventricular rate), but they are rarely *caused* by it. In fact, Digoxin is contraindicated in WPW syndrome with AFib. **High-Yield Clinical Pearls for NEET-PG:** 1. **Most Common Arrhythmia:** Ventricular Bigeminy. 2. **Most Characteristic Arrhythmia:** Atrial tachycardia with AV block. 3. **Most Fatal Arrhythmia:** Ventricular Fibrillation. 4. **Electrolyte Triggers:** Hypokalemia, Hypomagnesemia, and Hypercalcemia predispose to toxicity. 5. **Visual Symptom:** Xanthopsia (yellow-green vision). 6. **Antidote:** Digoxin Immune Fab (Digibind). 7. **ECG Change (Therapeutic):** "Reverse Tick" or "Sagging" ST-segment depression (not a sign of toxicity).

Question 83: Vorapaxar acts by inhibiting which receptor?

A. GPIIa/IIIb
B. P2Y12 receptor
C. PAR-1 (Correct Answer)
D. Antithrombin-3

Explanation: **Explanation:** **Vorapaxar** is a novel antiplatelet agent that acts as a **competitive and reversible antagonist of the Protease-Activated Receptor-1 (PAR-1)**. Thrombin is the most potent activator of platelets; it binds to PAR-1 on the platelet surface to trigger aggregation. By blocking this receptor, Vorapaxar inhibits thrombin-induced platelet activation without interfering with thrombin's ability to convert fibrinogen to fibrin (coagulation). It is clinically indicated for the reduction of thrombotic cardiovascular events in patients with a history of myocardial infarction (MI) or peripheral arterial disease (PAD). **Analysis of Incorrect Options:** * **A. GPIIa/IIIb:** These receptors (Integrin αIIbβ3) are the "final common pathway" for platelet aggregation. Drugs inhibiting this include **Abciximab, Eptifibatide, and Tirofiban**. * **B. P2Y12 receptor:** This is an ADP receptor. Drugs inhibiting this include thienopyridines (**Clopidogrel, Prasugrel**) and non-thienopyridines (**Ticagrelor, Cangrelor**). * **D. Antithrombin-3:** This is a natural anticoagulant that inactivates thrombin and Factor Xa. Drugs like **Heparin** act by binding to and accelerating the activity of Antithrombin-3. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** PAR-1 Antagonist (inhibits thrombin-mediated platelet activation). * **Pharmacokinetics:** It has a very long half-life (approx. 8 days), making its effects effectively irreversible in clinical practice. * **Contraindication:** It is strictly contraindicated in patients with a history of **Stroke, TIA, or Intracranial Hemorrhage** due to a significantly increased risk of bleeding. * **Metabolism:** Metabolized by **CYP3A4**; avoid use with strong inhibitors (e.g., Ketoconazole) or inducers (e.g., Rifampin).

Question 84: A 34-year-old lady on antihypertensives presented with certain features. Which of the following drugs is likely responsible for this condition?

A. Enalapril
B. Trimetazidine
C. Methyldopa
D. Minoxidil (Correct Answer)

Explanation: ***Minoxidil*** - **Minoxidil** is a potent vasodilator that commonly causes **hypertrichosis** (excessive hair growth), particularly noticeable in women as unwanted facial and body hair. - This **cosmetic side effect** is dose-dependent and reversible upon discontinuation, making it a characteristic adverse effect of minoxidil therapy. *Enalapril* - **ACE inhibitors** like enalapril typically cause a **dry cough** (10-15% of patients) due to increased bradykinin levels. - Other common side effects include **hyperkalemia** and **angioedema**, but not hypertrichosis. *Trimetazidine* - This **anti-anginal agent** works by optimizing cardiac metabolism and rarely causes significant cosmetic side effects. - Main adverse effects include **gastrointestinal disturbances** and occasional **movement disorders**, not hair growth changes. *Methyldopa* - **Methyldopa** commonly causes **sedation**, **depression**, and **positive Coombs test** leading to hemolytic anemia. - Other notable side effects include **hepatotoxicity** and **drug-induced lupus**, but hypertrichosis is not associated with this medication.

Question 85: In low doses, aspirin primarily acts on which enzyme?

A. Cyclooxygenase (Correct Answer)
B. Thromboxane A2 synthase
C. PGI2 synthase
D. Lipoxygenase

Explanation: **Explanation:** **Aspirin (Acetylsalicylic Acid)** is a non-steroidal anti-inflammatory drug (NSAID) that acts by **irreversibly inhibiting the enzyme Cyclooxygenase (COX-1 and COX-2)**. It achieves this by acetylating a serine residue at the active site of the enzyme. **Why Option A is correct:** At **low doses (75–150 mg/day)**, aspirin is highly selective for **COX-1** found in platelets. Because platelets are anuclear, they cannot synthesize new enzymes. This leads to a permanent inhibition of COX-1 for the entire lifespan of the platelet (7–10 days), effectively preventing the formation of Thromboxane A2 (TXA2), a potent platelet aggregator. **Why other options are incorrect:** * **B. Thromboxane A2 synthase:** Aspirin inhibits the *precursor* enzyme (COX) that produces cyclic endoperoxides (PGG2/PGH2). It does not directly inhibit the specific TXA2 synthase enzyme. * **C. PGI2 synthase:** While high doses of aspirin can inhibit COX in endothelial cells (reducing Prostacyclin/PGI2), low-dose aspirin spares endothelial COX because these nucleated cells can regenerate the enzyme. * **D. Lipoxygenase:** This enzyme is part of the leukotriene pathway. Aspirin does not inhibit lipoxygenase; in fact, by blocking the COX pathway, it may "shunt" arachidonic acid toward the lipoxygenase pathway, potentially triggering "aspirin-exacerbated respiratory disease" (AERD). **High-Yield Clinical Pearls for NEET-PG:** * **Antiplatelet effect:** Occurs at low doses (75–325 mg). * **Analgesic/Antipyretic effect:** Occurs at intermediate doses (0.3–2 g). * **Anti-inflammatory effect:** Occurs at high doses (3–5 g). * **Zero-order kinetics:** Aspirin shifts from first-order to zero-order kinetics at therapeutic/toxic doses. * **Reye’s Syndrome:** Avoid aspirin in children with viral infections (except in Kawasaki disease).

Question 86: What is the primary adverse effect of the combination use of beta-blockers and calcium channel blockers?

A. Heart block (Correct Answer)
B. Hypertension
C. Hypotension
D. All of the above

Explanation: ### Explanation **1. Why Heart Block is the Correct Answer** The combination of **Beta-blockers** (e.g., Propranolol, Atenolol) and **Non-dihydropyridine Calcium Channel Blockers (CCBs)** (specifically **Verapamil** and **Diltiazem**) is a classic "high-risk" drug interaction [1]. Both drug classes exert potent **negative inotropic** (force of contraction), **negative chronotropic** (heart rate), and **negative dromotropic** (conduction velocity) effects. Specifically, they both act on the **Sinoatrial (SA) node** and the **Atrioventricular (AV) node**. When used together, their synergistic suppression of the AV node can lead to severe bradycardia and various degrees of **AV block (Heart block)**, potentially resulting in cardiac arrest [2]. **2. Why the Other Options are Incorrect** * **B. Hypertension:** This is incorrect because both drug classes are antihypertensives. Their combined effect would lower blood pressure, not raise it. * **C. Hypotension:** While hypotension *can* occur due to decreased cardiac output [1], it is a secondary hemodynamic consequence. The **primary, direct electrophysiological risk** and the most characteristic "textbook" danger of this specific combination is the impairment of cardiac conduction (Heart block) [2]. * **D. All of the above:** Incorrect as hypertension is not a result of this interaction. **3. Clinical Pearls & High-Yield Facts for NEET-PG** * **Verapamil vs. Diltiazem:** Verapamil has the strongest depressant effect on the AV node; therefore, the combination of **Verapamil + Beta-blocker** is strictly contraindicated. * **Dihydropyridines (DHP):** CCBs like **Amlodipine** or Nifedipine primarily act on peripheral blood vessels. They are often safely combined with beta-blockers to counteract reflex tachycardia [2]. * **Mechanism:** Beta-blockers inhibit $G_s$ protein-coupled receptors, while CCBs block L-type calcium channels. Both ultimately reduce intracellular calcium, leading to additive cardiosuppression.

Question 87: All of the following beta blockers have intrinsic sympathomimetic activity EXCEPT:

A. Celiprolol
B. Propranolol (Correct Answer)
C. Pindolol
D. Acebutalol

Explanation: **Explanation:** The question tests the knowledge of **Intrinsic Sympathomimetic Activity (ISA)**, also known as partial agonist activity. Beta-blockers with ISA do not cause a complete blockade of beta-receptors; instead, they stimulate them weakly while preventing the binding of more potent endogenous catecholamines. **1. Why Propranolol is the correct answer:** Propranolol is a **pure beta-antagonist** (non-selective). It lacks ISA, meaning it provides a complete blockade of $\beta_1$ and $\beta_2$ receptors. This results in a more significant reduction in resting heart rate and cardiac output compared to drugs with ISA. Because it lacks ISA, it is more likely to cause profound bradycardia and is the gold standard for conditions requiring strict heart rate control. **2. Analysis of incorrect options (Drugs WITH ISA):** * **Pindolol:** A non-selective beta-blocker with the highest degree of ISA. It is the classic example used in exams. * **Acebutolol:** A cardioselective ($\beta_1$) blocker that possesses significant ISA. * **Celiprolol:** A unique third-generation cardioselective blocker that has ISA at $\beta_2$ receptors (causing bronchodilation) and antagonist activity at $\beta_1$ receptors. **3. High-Yield Clinical Pearls for NEET-PG:** * **Benefit of ISA:** These drugs cause less resting bradycardia and less coldness of extremities (Raynaud's-like symptoms) because they maintain a basal level of receptor stimulation. * **Contraindication:** Drugs with ISA are generally **avoided** in the immediate post-MI period and in patients with severe angina because they do not reduce the myocardial oxygen demand as effectively as pure antagonists like Propranolol or Atenolol. * **Mnemonic for ISA:** "**P**apa **A**nd **C**hild **L**ove **O**ats" (**P**indolol, **A**cebutolol, **C**eliprolol, **L**abetalol, **O**xprenolol).

Question 88: What is the mechanism of action of nifedipine?

A. It has a prominent smooth muscle relaxant action causing arteriolar dilation leading to a fall in blood pressure. (Correct Answer)
B. Nifedipine depresses the SA node, thus decreasing myocardial excitability.
C. Mainly depression of A-V conduction.
D. Decreases cardiac output, thus decreasing the load on the myocardium.

Explanation: **Explanation:** Nifedipine is a **Dihydropyridine (DHP)** Calcium Channel Blocker (CCB). Its primary mechanism involves blocking L-type voltage-gated calcium channels in the vascular smooth muscle. This inhibits the influx of calcium, leading to significant **arteriolar vasodilation** and a subsequent decrease in total peripheral resistance (TPR), which lowers blood pressure. **Analysis of Options:** * **Option A (Correct):** DHPs like nifedipine have a much higher affinity for vascular smooth muscle than for cardiac muscle. This results in potent peripheral vasodilation, making it an effective antihypertensive. * **Option B & C (Incorrect):** These actions describe **Non-Dihydropyridines** (Verapamil and Diltiazem). Verapamil has a prominent effect on the SA node (decreasing heart rate) and the AV node (slowing conduction). Nifedipine has negligible effects on cardiac conduction at clinical doses. * **Option D (Incorrect):** Nifedipine does not primarily decrease cardiac output. In fact, due to the rapid fall in blood pressure, it often triggers **reflex tachycardia**, which can actually increase cardiac output. **High-Yield Clinical Pearls for NEET-PG:** * **Reflex Tachycardia:** A common side effect of short-acting nifedipine; it is less common with long-acting (ER) formulations or Amlodipine. * **Side Effects:** Peripheral edema (due to precapillary vasodilation), headache, flushing, and gingival hyperplasia. * **Drug of Choice:** Nifedipine is frequently used in the management of **hypertension in pregnancy** and **Raynaud’s phenomenon**. * **Contraindication:** Short-acting nifedipine is avoided in acute MI as reflex tachycardia increases myocardial oxygen demand.

Question 89: Propranolol is contraindicated in diabetes mellitus due to which of the following reasons?

A. Causes hyperglycemia
B. Causes seizures
C. Masks the hypoglycemic symptoms (Correct Answer)
D. Causes hypotension

Explanation: **Explanation:** **1. Why Option C is Correct:** Propranolol is a non-selective beta-blocker ($\beta_1$ and $\beta_2$). In diabetic patients, particularly those on insulin or oral hypoglycemics, an overdose can lead to hypoglycemia. The body’s physiological response to low blood glucose is a "sympathetic surge," causing symptoms like **tachycardia, palpitations, and tremors**. Propranolol blocks these $\beta$-mediated warning signs, "masking" the hypoglycemia. This prevents the patient from recognizing the emergency, potentially leading to hypoglycemic coma. **Note:** Sweating is mediated by cholinergic fibers (sympathetic postganglionic), so it is **not** masked by propranolol and remains a key sign of hypoglycemia in these patients. **2. Why Other Options are Incorrect:** * **Option A (Hyperglycemia):** While $\beta_2$ blockade can slightly impair insulin release and glycogenolysis (potentially causing hyperglycemia or delaying recovery from hypoglycemia), the primary *contraindication* is the dangerous masking effect. * **Option B (Seizures):** Propranolol does not directly cause seizures. While severe hypoglycemia can lead to seizures, the drug itself is not the primary trigger. * **Option C (Hypotension):** While propranolol lowers blood pressure, this is its therapeutic effect in hypertension, not the specific reason it is contraindicated in diabetes. **3. NEET-PG High-Yield Pearls:** * **Metabolic Effect:** $\beta_2$ blockade inhibits glycogenolysis and gluconeogenesis in the liver, delaying recovery from hypoglycemia. * **Preferred Alternative:** If a beta-blocker is essential for a diabetic patient (e.g., post-MI), **Cardioselective ($\beta_1$) blockers** like Metoprolol or Atenolol are preferred as they have less effect on $\beta_2$ receptors. * **The "Sweating" Exception:** Sweating is the only sympathetic symptom of hypoglycemia **not** blocked by propranolol.

Question 90: Which of the following drugs does NOT increase nitric oxide levels?

A. Glycerine trinitrate
B. Hydralazine
C. Sodium Nitroprusside
D. Fenoldopam (Correct Answer)

Explanation: **Explanation:** The correct answer is **Fenoldopam** because its mechanism of action is entirely independent of the Nitric Oxide (NO) pathway. **1. Why Fenoldopam is the correct answer:** Fenoldopam is a selective **Dopamine $D_1$ receptor agonist**. It causes vasodilation by increasing intracellular cyclic AMP (cAMP) in vascular smooth muscle cells. It is unique because it causes rapid vasodilation while simultaneously increasing renal perfusion and promoting natriuresis (sodium excretion). It does not involve the release or stimulation of Nitric Oxide. **2. Why the other options are incorrect:** * **Glycerine trinitrate (GTN):** An organic nitrate that undergoes enzymatic conversion (via mitochondrial aldehyde dehydrogenase) to release **Nitric Oxide (NO)**, which activates guanylyl cyclase to increase cGMP. * **Sodium Nitroprusside (SNP):** A direct-acting vasodilator that non-enzymatically releases **Nitric Oxide** into the bloodstream. It acts on both arterioles and venules. * **Hydralazine:** Though its mechanism is complex, it is known to stimulate the release of **Nitric Oxide** from the vascular endothelium, leading to arteriolar vasodilation. **3. NEET-PG Clinical Pearls:** * **Fenoldopam** is the drug of choice for hypertensive emergencies in patients with **renal insufficiency** due to its renal-sparing effects. * **Sodium Nitroprusside** can lead to **Cyanide/Thiocyanate toxicity** with prolonged use; the antidote is Sodium Thiosulfate or Hydroxocobalamin. * **Nitrates** primarily cause venodilation (reducing preload), whereas **Hydralazine** primarily causes arteriolar dilation (reducing afterload). * **Tachyphylaxis** (tolerance) is a common issue with chronic Nitrate use, requiring a "nitrate-free interval."

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

Want unlimited practice?

Get full access to all questions, explanations, and performance tracking.

Start For Free