Cardiovascular Drugs — MCQs

Cardiovascular Drugs Indian Medical PG Practice Questions and MCQs

Question 131: Which of the following drugs does not act by blocking Gp IIb/IIIa receptors?

A. Abciximab
B. Eptifibatide
C. Tirofiban
D. Clopidogrel (Correct Answer)

Explanation: **Explanation:** The question tests the classification of antiplatelet agents based on their mechanism of action. **1. Why Clopidogrel is the correct answer:** Clopidogrel is a **P2Y12 receptor antagonist**. It works by irreversibly inhibiting the ADP (Adenosine Diphosphate) receptor on the platelet surface. This inhibition prevents the activation of the Gp IIb/IIIa receptor complex, thereby inhibiting platelet aggregation. It does **not** bind directly to the Gp IIb/IIIa receptor itself. **2. Why the other options are incorrect:** Options A, B, and C are all direct **Gp IIb/IIIa inhibitors**, often referred to as the "final common pathway" inhibitors of platelet aggregation: * **Abciximab (A):** A chimeric monoclonal antibody fragment that binds irreversibly to Gp IIb/IIIa receptors. * **Eptifibatide (B):** A cyclic peptide that acts as a reversible competitive inhibitor (derived from rattlesnake venom). * **Tirofiban (C):** A non-peptide small molecule that acts as a reversible competitive inhibitor. **3. High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Gp IIb/IIIa receptors normally bind to **fibrinogen** and von Willebrand factor to form cross-links between platelets. * **Route of Administration:** All Gp IIb/IIIa inhibitors are administered **intravenously**, whereas Clopidogrel is administered **orally**. * **Side Effects:** The most significant side effect of Gp IIb/IIIa inhibitors is bleeding and **thrombocytopenia** (especially with Abciximab). * **Clopidogrel Metabolism:** It is a **prodrug** activated by the hepatic enzyme **CYP2C19**. Drugs like Omeprazole can inhibit this enzyme, reducing Clopidogrel's efficacy.

Question 132: What is the half-life of alteplase?

A. 5 minutes (Correct Answer)
B. 30 minutes
C. 1 hour
D. 2 hours

Explanation: **Explanation:** **Alteplase (recombinant Tissue Plasminogen Activator - rtPA)** is a fibrin-specific thrombolytic agent. The correct answer is **5 minutes** because alteplase is rapidly cleared from the plasma, primarily by the liver. 1. **Why 5 minutes is correct:** Alteplase has a very short initial half-life ($t_{1/2}$) of approximately **4–6 minutes**. This rapid clearance is clinically significant because it allows for precise control over fibrinolysis; however, it also necessitates a specific dosing regimen—usually an intravenous bolus followed by a continuous infusion—to maintain therapeutic levels during the treatment of acute myocardial infarction, ischemic stroke, or pulmonary embolism. 2. **Why the other options are incorrect:** * **30 minutes:** This is too long for alteplase but is closer to the half-life of **Reteplase** (approx. 13–15 mins) or **Streptokinase** (approx. 20 mins). * **1 hour / 2 hours:** These durations are far beyond the metabolic clearance rate of first-generation or second-generation thrombolytics. By 1–2 hours, more than 90% of alteplase has already been cleared from the systemic circulation. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** It converts plasminogen to plasmin directly. It is "clot-specific," meaning it preferentially activates plasminogen bound to fibrin, reducing (but not eliminating) systemic fibrinogenolysis compared to streptokinase. * **Antidote:** In cases of severe bleeding due to thrombolytics, **Epsilon-aminocaproic acid** or **Tranexamic acid** can be used. * **Comparison:** **Tenecteplase (TNK-tPA)** has a longer half-life (approx. 20 mins) and higher fibrin specificity than alteplase, allowing for convenient single-bolus administration.

Question 133: What is the drug of choice in paroxysmal supraventricular tachycardia?

A. Digoxin
B. Adenosine (Correct Answer)
C. Nifedipine
D. Esmolol

Explanation: **Explanation:** **Adenosine** is the drug of choice for the acute termination of Paroxysmal Supraventricular Tachycardia (PSVT), specifically AV nodal re-entrant tachycardia (AVNRT). It acts by stimulating A1 receptors on the AV node, leading to the activation of acetylcholine-sensitive inward rectifying potassium channels ($I_{K-ACh}$) and inhibition of calcium uptake. This results in profound hyperpolarization and a transient "chemical cardioversion" by blocking AV conduction. Its ultra-short half-life (<10 seconds) makes it ideal for rapid action and quick recovery from side effects. **Analysis of Incorrect Options:** * **Digoxin:** While it increases vagal tone and slows AV conduction, its onset of action is too slow (hours) for acute termination of PSVT. It is primarily used for rate control in atrial fibrillation. * **Nifedipine:** This is a dihydropyridine calcium channel blocker that acts mainly on vascular smooth muscle (vasodilation). It has no significant effect on cardiac conduction and may cause reflex tachycardia, worsening the condition. * **Esmolol:** This is a short-acting beta-blocker. While it can be used for rate control, it is generally a second-line agent behind Adenosine or Verapamil for converting PSVT. **High-Yield Clinical Pearls for NEET-PG:** * **Administration:** Must be given as a **rapid IV bolus** (usually 6mg, followed by 12mg) through a large-bore peripheral vein, followed by a saline flush, due to its rapid degradation by erythrocytes and endothelial cells. * **Contraindications:** Avoid in **Asthmatics** (can cause bronchospasm via A2B receptors) and patients with **high-grade AV block**. * **Interactions:** **Theophylline/Caffeine** (adenosine receptor antagonists) decrease its effect, while **Dipyridamole** (uptake inhibitor) potentiates it. * **Common Side Effect:** Patients often experience a transient, distressing feeling of "impending doom," chest pain, or flushing.

Question 134: Which drug inhibits the Na+-K+ ATPase pump?

A. Digitalis (Correct Answer)
B. Amiodarone
C. Verapamil
D. Hydralazine

Explanation: ### Explanation **Correct Option: A. Digitalis** Digitalis (Digoxin) is a cardiac glycoside that acts by **reversibly inhibiting the Na⁺-K⁺ ATPase pump** (sodium pump) located on the sarcolemma of cardiac myocytes. * **Mechanism:** By inhibiting this pump, there is an increase in intracellular sodium ($Na^+$). This high intracellular $Na^+$ decreases the concentration gradient that drives the **Na⁺-Ca²⁺ exchanger (NCX)**. * **Result:** Consequently, calcium ($Ca^{2+}$) extrusion from the cell is reduced, leading to increased intracellular $Ca^{2+}$ stores in the sarcoplasmic reticulum. This results in a **positive inotropic effect** (increased force of contraction), making it useful in Heart Failure and Atrial Fibrillation. **Analysis of Incorrect Options:** * **B. Amiodarone:** A Class III antiarrhythmic drug. Its primary mechanism is **blocking Potassium ($K^+$) channels**, though it also has Class I, II, and IV activity. * **C. Verapamil:** A non-dihydropyridine **Calcium Channel Blocker (CCB)**. It blocks L-type calcium channels, primarily in the AV node and myocardium. * **D. Hydralazine:** A direct-acting **arteriolar vasodilator**. It acts by increasing cGMP levels and inhibiting $Ca^{2+}$ release from the sarcoplasmic reticulum in vascular smooth muscle. **High-Yield Clinical Pearls for NEET-PG:** * **ECG Changes in Digoxin:** The most characteristic sign is the **"reverse tick" or "Sagging" ST-segment depression** (Salvador Dali mustache sign). * **Electrolyte Interaction:** **Hypokalemia** predisposes to Digoxin toxicity because $K^+$ and Digoxin compete for the same binding site on the Na⁺-K⁺ ATPase pump. * **Antidote:** Digoxin-specific antibody fragments (**DigiFab/Digibind**). * **Visual Side Effect:** Xanthopsia (yellowish-green vision).

Question 135: ACE inhibitors are contraindicated in bilateral renal artery stenosis, because:

A. Angiotensin II has a direct effect on GFR (Correct Answer)
B. They enhance bradykinin action
C. Hyperreninism affects renal parenchyma
D. They affect prostaglandins

Explanation: In the setting of **bilateral renal artery stenosis (RAS)**, renal perfusion pressure is significantly reduced. To maintain an adequate **Glomerular Filtration Rate (GFR)**, the kidney relies on a compensatory mechanism mediated by the Renin-Angiotensin-Aldosterone System (RAAS) [2]. **Angiotensin II** plays a critical role here by causing **selective vasoconstriction of the efferent arteriole** [1]. This increases intraglomerular hydrostatic pressure, effectively "propping up" the GFR despite low inflow pressure [1]. When an ACE inhibitor is administered, it prevents the formation of Angiotensin II, leading to efferent arteriolar vasodilation. This causes a precipitous drop in intraglomerular pressure, resulting in **acute renal failure**. Thus, the direct effect of Angiotensin II on GFR (via efferent tone) is the physiological basis for this contraindication. **Analysis of Incorrect Options:** * **Option B:** While ACE inhibitors do increase bradykinin (leading to side effects like cough and angioedema), this mechanism is unrelated to the acute decline in GFR seen in RAS. * **Option C:** Hyperreninism is a consequence of reduced renal blood flow, but it is the hormonal product (Angiotensin II), not the renin itself, that maintains filtration. * **Option D:** Prostaglandins help maintain the *afferent* arteriole's patency. While NSAIDs (which inhibit prostaglandins) can also worsen GFR in RAS, this is not the mechanism by which ACE inhibitors act. **High-Yield Clinical Pearls for NEET-PG:** * **Diagnostic Clue:** Suspect bilateral RAS if a patient’s serum creatinine rises by **>30%** after starting an ACE inhibitor or ARB. * **Other Contraindications:** ACE inhibitors are strictly contraindicated in **pregnancy** (teratogenic—renal dysgenesis) and patients with a history of **angioedema**. * **Drug of Choice:** ACE inhibitors remain the first-line treatment for diabetic nephropathy as they are renoprotective in the long term by reducing protein excretion.

Question 136: Fenoldopam is used in which of the following conditions?

A. Hypertensive emergencies (Correct Answer)
B. Orthostatic hypotension
C. Congestive heart failure (CHF)
D. Angina

Explanation: **Explanation:** **Fenoldopam** is a unique pharmacological agent that acts as a **selective post-synaptic Dopamine-1 (D1) receptor agonist**. Its primary clinical utility lies in the management of **Hypertensive Emergencies** (Option A). **Why Option A is Correct:** Activation of D1 receptors leads to potent **arteriolar vasodilation** and a reduction in peripheral vascular resistance. A key feature of Fenoldopam is its ability to cause **renal vasodilation**, which increases renal blood flow and promotes **natriuresis** (sodium excretion) and diuresis. This makes it particularly beneficial for hypertensive patients with concomitant renal impairment, as it maintains organ perfusion while lowering blood pressure. **Why Other Options are Incorrect:** * **B. Orthostatic Hypotension:** This condition requires vasopressors (like Midodrine) or volume expanders. Fenoldopam, being a vasodilator, would worsen hypotension. * **C. Congestive Heart Failure (CHF):** While vasodilators are used in CHF, Fenoldopam is not a standard treatment. Inotropes (like Dobutamine) or ACE inhibitors are preferred. * **D. Angina:** Nitrates and Beta-blockers are the mainstays. Fenoldopam may cause reflex tachycardia, which increases myocardial oxygen demand and could exacerbate angina. **High-Yield Clinical Pearls for NEET-PG:** * **Route:** Administered via continuous intravenous infusion due to a short half-life (~5–10 minutes). * **Unique Benefit:** It is the only parenteral antihypertensive that improves renal perfusion. * **Side Effects:** Headache, flushing, and a dose-dependent increase in **intraocular pressure** (use with caution in glaucoma). * **Comparison:** Unlike Sodium Nitroprusside, Fenoldopam does not carry the risk of cyanide toxicity.

Question 137: Which of the following agents is a Neprilysin inhibitor?

A. Carperitide
B. Neseritide
C. Sacubitril (Correct Answer)
D. Ularitide

Explanation: **Explanation:** **Sacubitril** is a prodrug that, upon activation to sacubitrilat, inhibits the enzyme **Neprilysin** (neutral endopeptidase). Neprilysin is responsible for the degradation of endogenous vasoactive peptides, including Atrial Natriuretic Peptide (ANP), B-type Natriuretic Peptide (BNP), and bradykinin. By inhibiting this enzyme, Sacubitril increases the levels of these peptides, leading to vasodilation, natriuresis, and diuresis, which counteracts the maladaptive vasoconstriction and fluid retention seen in heart failure. **Analysis of Incorrect Options:** * **Carperitide:** This is a recombinant form of human **Atrial Natriuretic Peptide (ANP)**. It acts as an agonist at natriuretic peptide receptors, not as an enzyme inhibitor. * **Neseritide:** This is a recombinant form of human **B-type Natriuretic Peptide (BNP)** used in acute decompensated heart failure. Like Carperitide, it is a peptide analog, not a neprilysin inhibitor. * **Ularitide:** This is a synthetic form of **Urodilatin** (a natriuretic peptide produced in the kidneys). It also functions as a receptor agonist. **High-Yield Clinical Pearls for NEET-PG:** * **ARNI:** Sacubitril is clinically used in a fixed-dose combination with Valsartan (an ARB), known as an **Angiotensin Receptor-Neprilysin Inhibitor (ARNI)**. * **Indication:** It is a first-line therapy for Heart Failure with Reduced Ejection Fraction (HFrEF) to reduce mortality and hospitalizations. * **Contraindication:** It must **not** be administered with an ACE inhibitor due to a significantly increased risk of **angioedema** (both drugs prevent the breakdown of bradykinin). A washout period of **36 hours** is required when switching from an ACE inhibitor to an ARNI.

Question 138: Combination use of beta blockers and calcium channel blockers can cause which of the following?

A. Heart block
B. Hypotension
C. Bradycardia
D. All of these (Correct Answer)

Explanation: ### Explanation The combination of **Beta-blockers (BBs)** and **Calcium Channel Blockers (CCBs)**, particularly the non-dihydropyridines like **Verapamil** and **Diltiazem**, is generally avoided or used with extreme caution due to their synergistic inhibitory effects on the heart. **Why "All of these" is correct:** Both BBs and non-dihydropyridine CCBs exert negative inotropic (force), negative chronotropic (rate), and negative dromotropic (conduction) effects. 1. **Heart Block:** Both drug classes depress the **Atrioventricular (AV) node**. When combined, they significantly prolong the PR interval, which can progress to complete heart block. 2. **Bradycardia:** Both classes suppress the **Sinoatrial (SA) node** firing rate. Their additive effect can lead to severe sinus bradycardia. 3. **Hypotension:** BBs reduce cardiac output, while CCBs cause peripheral vasodilation and further reduce myocardial contractility. Together, they can lead to a profound drop in blood pressure. **Evaluation of Options:** * **A, B, and C** are all individual physiological consequences of the combined pharmacodynamic profile of these drugs. Since all three occur simultaneously or as part of the same clinical picture, "All of these" is the most comprehensive answer. **High-Yield Clinical Pearls for NEET-PG:** * **The "Verapamil Rule":** Intravenous Verapamil is strictly contraindicated in patients already taking Beta-blockers due to the high risk of asystole. * **Dihydropyridines (e.g., Amlodipine):** These are safer to combine with BBs because they primarily cause vasodilation and may even trigger reflex tachycardia, which BBs help counteract. * **Antidote:** In cases of toxicity from this combination, **Glucagon** is the drug of choice as it increases cAMP levels in the heart via non-adrenergic pathways, bypassing the blocked receptors.

Question 139: All of the following are cardioselective beta blockers EXCEPT?

A. Atenolol
B. Esmolol
C. Bisoprolol
D. Propranolol (Correct Answer)

Explanation: **Explanation:** The question tests the classification of beta-blockers based on their receptor selectivity. Beta-blockers are divided into non-selective (Generation I) and cardioselective (Generation II). **1. Why Propranolol is the correct answer:** **Propranolol** is a **non-selective (1st generation) beta-blocker**. It blocks both $\beta_1$ receptors (located primarily in the heart) and $\beta_2$ receptors (located in bronchial smooth muscle, blood vessels, and liver). Because it lacks selectivity, it is contraindicated in patients with bronchial asthma or COPD due to the risk of bronchospasm. **2. Why the other options are incorrect:** Options A, B, and C are all **Cardioselective ($\beta_1$ selective) blockers**. They primarily inhibit $\beta_1$ receptors at standard doses, making them safer for patients with respiratory issues or diabetes. * **Atenolol:** A long-acting, hydrophilic $\beta_1$ blocker commonly used for hypertension. * **Esmolol:** An ultra-short-acting $\beta_1$ blocker (half-life ~9 minutes) administered IV, used for acute arrhythmias or intraoperative tachycardia. * **Bisoprolol:** A highly selective $\beta_1$ blocker often preferred in the management of chronic heart failure. **3. High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for Cardioselective ($\beta_1$) blockers:** *"**A**ll **N**ew **B**eta **B**lockers **E**xert **M**ainly **C**ardioselective **A**ctions"* (**A**tenolol, **N**ebivolol, **B**isoprolol, **B**etaxolol, **E**smolol, **M**etoprolol, **C**eliprolol, **A**cebutolol). * **Nebivolol** is the most highly selective $\beta_1$ blocker and also possesses vasodilatory properties via Nitric Oxide (NO) release. * **Propranolol** is highly lipid-soluble, crosses the blood-brain barrier, and is the drug of choice for **prophylaxis of migraine** and **essential tremors**.

Question 140: Which of the following antihypertensive agents is contraindicated in patients with chronic renal disease?

A. Hydrochlorothiazide-triamterene (Correct Answer)
B. Furosemide
C. Prazosin
D. Nifedipine

Explanation: **Explanation:** The correct answer is **A. Hydrochlorothiazide-triamterene**. **Why it is correct:** This combination contains **Triamterene**, a potassium-sparing diuretic. In chronic renal disease (CRD), the kidneys' ability to excrete potassium is significantly impaired. Using potassium-sparing agents like triamterene, amiloride, or spironolactone in these patients poses a high risk of life-threatening **hyperkalemia**. Furthermore, **Thiazides** (like Hydrochlorothiazide) lose their efficacy as monotherapy when the Glomerular Filtration Rate (GFR) falls below 30 mL/min, making this combination both dangerous and ineffective in advanced renal failure. **Why the other options are incorrect:** * **B. Furosemide:** This is a loop diuretic and is the **diuretic of choice** in patients with renal impairment. Unlike thiazides, loop diuretics remain effective even at low GFR levels and help manage fluid overload in CRD. * **C. Prazosin:** This is an alpha-1 blocker. It is primarily metabolized by the liver and does not require significant dose adjustment in renal failure, making it safe for use. * **D. Nifedipine:** This is a Calcium Channel Blocker (CCB). CCBs are generally safe in renal disease as they do not adversely affect renal hemodynamics and are often used to manage hypertension in these patients. **High-Yield Clinical Pearls for NEET-PG:** * **Hyperkalemia Risk:** Always avoid the "K-SPARE" drugs (Spironolactone, Amiloride, Triamterene) and ACE inhibitors/ARBs in patients with advanced renal failure or high baseline potassium. * **Thiazide Limit:** Thiazides are generally ineffective if **CrCl < 30 mL/min** (Exception: Metolazone). * **Drug of Choice:** Loop diuretics (Furosemide) are preferred for edema/hypertension in renal insufficiency.

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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