Cardiovascular Drugs — MCQs

Cardiovascular Drugs Indian Medical PG Practice Questions and MCQs

Question 851: What is the mechanism of aspirin action?

A. Converts inactive plasminogen into active plasmin
B. Inhibits COX and thus thromboxane synthesis (Correct Answer)
C. Enhances the interaction between antithrombin III and both thrombin and the factors involved in the intrinsic clotting cascade
D. Inhibits the glycoprotein IIb/IIIa complex

Explanation: **Explanation:** **Correct Option (B):** Aspirin (Acetylsalicylic acid) acts by **irreversibly inhibiting the enzyme Cyclooxygenase-1 (COX-1)** via acetylation of a serine residue. In platelets, this inhibition prevents the conversion of arachidonic acid into **Thromboxane A2 (TXA2)**. Since TXA2 is a potent platelet aggregator and vasoconstrictor, its absence leads to an anti-platelet effect that lasts for the entire lifespan of the platelet (approx. 7–10 days), as platelets are anucleated and cannot synthesize new enzymes. **Incorrect Options:** * **Option A:** This describes the mechanism of **Thrombolytics/Fibrinolytics** (e.g., Streptokinase, Alteplase), which dissolve formed clots. * **Option C:** This describes the mechanism of **Heparin**. Heparin acts as a cofactor that accelerates Antithrombin III activity, primarily neutralizing Thrombin (IIa) and Factor Xa. * **Option D:** This describes the mechanism of **GP IIb/IIIa inhibitors** (e.g., Abciximab, Eptifibatide, Tirofiban), which block the "final common pathway" of platelet aggregation. **High-Yield Clinical Pearls for NEET-PG:** * **Low-dose aspirin (75–150 mg/day)** is selective for COX-1 (anti-platelet), while higher doses inhibit both COX-1 and COX-2 (analgesic/anti-inflammatory). * **Zero-order kinetics:** Aspirin follows first-order kinetics at low doses but shifts to zero-order kinetics at anti-inflammatory/toxic doses. * **Reye’s Syndrome:** Aspirin is contraindicated in children with viral infections (use Paracetamol instead). * **Aspirin Triad (Samter’s Triad):** Asthma, Nasal polyposis, and Aspirin intolerance.

Question 852: Which drug class inhibits the rate-limiting step in cholesterol synthesis?

A. Probucol
B. Statins (Correct Answer)
C. Cholestyramine
D. Gemfibrozil

Explanation: **Explanation:** **Statins (HMG-CoA Reductase Inhibitors)** are the correct answer because they competitively inhibit the enzyme **HMG-CoA reductase**. This enzyme catalyzes the conversion of HMG-CoA to mevalonate, which is the **rate-limiting step** in the endogenous synthesis of cholesterol in the liver. By reducing intracellular cholesterol levels, statins trigger an up-regulation of LDL receptors, leading to increased clearance of LDL from the plasma. **Analysis of Incorrect Options:** * **Probucol (A):** An older antioxidant drug that lowers LDL by increasing its catabolism and inhibits the oxidation of LDL. It is rarely used today due to its potential to lower HDL and prolong the QT interval. * **Cholestyramine (C):** A **Bile Acid Sequestrant**. It works in the intestine by binding to bile acids, preventing their enterohepatic circulation. This forces the liver to use more cholesterol to synthesize new bile acids, indirectly lowering plasma cholesterol. * **Gemfibrozil (D):** A **Fibrate**. Its primary mechanism is the activation of **PPAR-α** (Peroxisome Proliferator-Activated Receptor-alpha), which increases the activity of lipoprotein lipase. It is primarily used to lower triglycerides rather than cholesterol. **High-Yield Clinical Pearls for NEET-PG:** * **Pleiotropic Effects:** Statins have benefits beyond lipid-lowering, including plaque stabilization, anti-inflammatory effects, and improved endothelial function. * **Adverse Effects:** The most significant side effects are **myopathy/rhabdomyolysis** (monitored via CK levels) and **hepatotoxicity** (monitored via LFTs). * **Timing:** Statins with short half-lives (e.g., Simvastatin, Lovastatin) should be taken at **bedtime** because peak cholesterol synthesis occurs during the night. * **Contraindication:** Statins are strictly **contraindicated in pregnancy** (Teratogenic).

Question 853: Which of the following drugs can be used for the treatment of hypertension in a diabetic patient?

A. Losartan
B. Captopril
C. Amlodipine
D. All of these (Correct Answer)

Explanation: **Explanation:** The management of hypertension in diabetic patients requires drugs that are not only effective in lowering blood pressure but also metabolically neutral or Reno-protective. **1. Why "All of these" is correct:** * **ACE Inhibitors (Captopril) and ARBs (Losartan):** These are the **drugs of choice (DOC)** for hypertensive diabetics [1]. They provide significant **nephroprotection** by dilating the efferent arteriole, which reduces intraglomerular pressure and slows the progression of diabetic nephropathy (microalbuminuria). * **Calcium Channel Blockers (Amlodipine):** These are metabolically neutral (they do not affect blood glucose or lipid profiles) and are highly effective as add-on therapy or as first-line agents in patients where ACE inhibitors are contraindicated [1]. **2. Analysis of Options:** * **Losartan (ARB):** Blocks AT1 receptors. It is preferred if patients develop a dry cough with ACE inhibitors. * **Captopril (ACEI):** Inhibits the conversion of Angiotensin I to II. It improves insulin sensitivity and prevents diabetic renal complications. * **Amlodipine (Dihydropyridine CCB):** A safe, long-acting vasodilator that does not interfere with glycemic control [1]. **Clinical Pearls for NEET-PG:** * **First-line for Diabetics:** ACEIs or ARBs (due to renal protection). * **Drugs to Avoid/Use Cautiously:** * **Thiazide Diuretics:** Can cause hyperglycemia and hypokalemia. * **Beta-Blockers (Non-selective):** Can mask the warning symptoms of hypoglycemia (tachycardia) and delay recovery from hypoglycemic episodes. Note that evidence supporting their routine use is less strong than for ACEIs or ARBs in primary hypertension [1]. * **Target BP in Diabetes:** Generally <130/80 mmHg.

Question 854: Nitrate causes all of the following EXCEPT:

A. Decrease in heart size
B. Increase in cardiac work (Correct Answer)
C. Preload reduction
D. Dilatation of cutaneous blood vessels

Explanation: **Explanation:** Nitrates are primarily **venodilators** that act by releasing Nitric Oxide (NO), which increases cGMP levels, leading to smooth muscle relaxation. **Why "Increase in cardiac work" is the correct answer:** Nitrates **decrease** cardiac work, not increase it. By causing significant peripheral venodilation, they increase venous capacitance and decrease venous return to the heart (preload). This reduction in preload leads to a decrease in ventricular wall tension and myocardial oxygen demand. Consequently, the total workload of the heart is reduced, which is the primary mechanism for relieving angina. **Analysis of other options:** * **Decrease in heart size:** By reducing preload and ventricular end-diastolic volume (EDV), the physical dimensions of the heart (stretch) decrease. * **Preload reduction:** This is the hallmark pharmacological effect of nitrates. They increase venous pooling, thereby reducing the volume of blood returning to the right atrium. * **Dilatation of cutaneous blood vessels:** Nitrates cause vasodilation of superficial vessels, particularly in the "blush area" (face and neck), which clinically manifests as flushing. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** Sublingual Nitroglycerin is the DOC for acute anginal attacks due to its rapid onset and avoidance of first-pass metabolism. * **Nitrate Tolerance:** Continuous exposure leads to "tachyphylaxis." A "nitrate-free interval" of 8–12 hours (usually at night) is required to restore sensitivity. * **Monday Disease:** Workers in explosives factories develop tolerance during the week but lose it over the weekend, leading to severe headaches and tachycardia upon re-exposure on Mondays. * **Contraindication:** Never co-administer with **Sildenafil** (PDE-5 inhibitors) as it can cause life-threatening hypotension.

Question 855: Riociguat is used in the treatment of:

A. Gouty arthritis
B. Rheumatoid arthritis
C. Chronic thromboembolic pulmonary hypertension (Correct Answer)
D. Obesity

Explanation: **Explanation:** **Riociguat** is a first-in-class **soluble Guanylate Cyclase (sGC) stimulator**. Its primary mechanism of action involves sensitizing sGC to endogenous Nitric Oxide (NO) and directly stimulating the enzyme independently of NO. This leads to increased synthesis of cyclic Guanylate Monophosphate (cGMP), resulting in potent vasodilation, anti-proliferative, and anti-fibrotic effects on the pulmonary vasculature. **Why Option C is correct:** Riociguat is FDA-approved for two specific indications: 1. **Chronic Thromboembolic Pulmonary Hypertension (CTEPH):** Specifically in patients who have persistent/recurrent pulmonary hypertension after surgical endarterectomy or those with inoperable CTEPH. 2. **Pulmonary Arterial Hypertension (PAH):** To improve exercise capacity (WHO Group 1). **Why other options are incorrect:** * **Options A & B (Gouty/Rheumatoid Arthritis):** These are inflammatory joint disorders. Riociguat has no anti-inflammatory or uricosuric properties. Drugs like NSAIDs, Colchicine, or DMARDs are used here. * **Option D (Obesity):** Riociguat does not affect metabolic rate or appetite. Drugs like Orlistat or GLP-1 agonists (Liraglutide) are indicated for obesity. **High-Yield Clinical Pearls for NEET-PG:** * **Contraindication:** It must **never** be co-administered with **PDE-5 inhibitors** (e.g., Sildenafil) or **Nitrates** due to the risk of severe, life-threatening hypotension. * **Teratogenicity:** It is contraindicated in pregnancy (Category X) and requires a restricted distribution program (REMS) in many regions. * **Side Effects:** Headache, dizziness, and dyspepsia are the most common adverse effects.

Question 856: A diabetic patient with bilateral renal artery stenosis requires a drug for the treatment of high blood pressure. Which of the following drugs will be most appropriate for this patient?

A. Hydrochlorothiazide
B. Metoprolol
C. Enalapril
D. Amlodipine (Correct Answer)

Explanation: **Explanation:** The correct answer is **D. Amlodipine.** **Why Amlodipine is the correct choice:** In patients with **bilateral renal artery stenosis (RAS)**, the glomerular filtration rate (GFR) is maintained by Angiotensin II-mediated vasoconstriction of the efferent arteriole. Amlodipine, a **Dihydropyridine Calcium Channel Blocker (CCB)**, acts by causing peripheral vasodilation without interfering with the renin-angiotensin-aldosterone system (RAAS). It effectively lowers blood pressure without compromising renal perfusion or GFR in the setting of RAS. Furthermore, CCBs are metabolically neutral, making them safe for diabetic patients. **Why other options are incorrect:** * **Enalapril (ACE Inhibitor):** This is **strictly contraindicated** in bilateral RAS. ACE inhibitors block the production of Angiotensin II, leading to vasodilation of the efferent arteriole. This causes a precipitous drop in intraglomerular pressure, resulting in acute renal failure. * **Hydrochlorothiazide (Thiazide Diuretic):** While not contraindicated in RAS, diuretics can worsen hyperglycemia and dyslipidemia, making them less ideal as first-line agents for diabetic patients. * **Metoprolol (Beta-blocker):** Beta-blockers can mask the symptoms of hypoglycemia (except sweating) and may impair the metabolic recovery from hypoglycemic episodes in diabetic patients. They are generally not the first-line choice for uncomplicated hypertension. **High-Yield Clinical Pearls for NEET-PG:** * **ACEIs/ARBs** are the drugs of choice for diabetics with proteinuria but are **absolute contraindications** in bilateral renal artery stenosis (or stenosis in a solitary kidney). * If a patient’s serum creatinine rises by **>30%** after starting an ACE inhibitor, suspect underlying Renal Artery Stenosis. * **Amlodipine** is preferred in RAS because it dilates the *afferent* arteriole more than the efferent, helping maintain GFR.

Question 857: Propranolol can be used in all of the following conditions except?

A. Thyrotoxicosis
B. Variant angina (Correct Answer)
C. Migraine
D. Hypertension

Explanation: **Explanation:** The correct answer is **Variant angina (Prinzmetal angina)**. Propranolol is a non-selective beta-blocker that is strictly contraindicated in this condition. **1. Why Variant Angina is the correct answer:** Variant angina is caused by **coronary artery vasospasm** rather than atherosclerosis. In the coronary vessels, there are both $\beta_2$ receptors (which cause vasodilation) and $\alpha_1$ receptors (which cause vasoconstriction). Propranolol blocks the $\beta_2$ receptors, leaving the $\alpha_1$-mediated vasoconstrictive effects **unopposed**. This can worsen the coronary spasm, potentially leading to myocardial infarction. **2. Analysis of Incorrect Options:** * **Thyrotoxicosis:** Propranolol is the drug of choice to control symptomatic tachycardia, tremors, and palpitations. It also uniquely inhibits the peripheral conversion of $T_4$ to the more active $T_3$. * **Migraine:** Propranolol is a first-line agent for the **prophylaxis** of migraine (not for acute attacks) due to its high lipid solubility and ability to cross the blood-brain barrier. * **Hypertension:** While no longer first-line for uncomplicated hypertension, beta-blockers remain an option, especially in patients with co-existing conditions like stable angina or post-MI. **High-Yield Clinical Pearls for NEET-PG:** * **DOC for Variant Angina:** Calcium Channel Blockers (CCBs) like Diltiazem or Nitrates. * **Other Contraindications for Propranolol:** Bronchial asthma/COPD (due to $\beta_2$ blockade causing bronchospasm), Bradycardia, and Second/Third-degree Heart Block. * **Metabolic effect:** Propranolol can mask the warning symptoms of hypoglycemia (tachycardia) in diabetic patients, except for sweating (which is mediated by cholinergic receptors).

Question 858: Which of the following is a potassium channel opener?

A. Nicorandil (Correct Answer)
B. Ranolazine
C. Ivabradine
D. Nitroprusside

Explanation: **Explanation:** **Correct Answer: A. Nicorandil** Nicorandil is a unique anti-anginal drug with a dual mechanism of action. It acts as a **Potassium Channel Opener ($K_{ATP}$ channels)** and a **Nitric Oxide (NO) donor**. By opening ATP-sensitive $K^+$ channels in vascular smooth muscle, it causes potassium efflux, leading to hyperpolarization and subsequent closure of voltage-gated calcium channels. This results in significant **arteriolar dilation** (reducing afterload). Simultaneously, its nitrate moiety increases cGMP, causing **venous dilation** (reducing preload). This dual action effectively reduces myocardial oxygen demand and improves coronary blood flow. **Analysis of Incorrect Options:** * **B. Ranolazine:** This is a **late sodium channel blocker**. It prevents the overload of intracellular calcium via the $Na^+/Ca^{2+}$ exchanger, thereby improving myocardial relaxation and reducing wall tension without affecting heart rate or blood pressure. * **C. Ivabradine:** This drug is a selective **$I_f$ (funny) current inhibitor** in the SA node. It reduces heart rate without affecting myocardial contractility or conduction, making it a "pure" bradycardic agent. * **D. Nitroprusside:** This is a potent **vasodilator** that acts by releasing Nitric Oxide (NO). It does not act on potassium channels; it stimulates guanylyl cyclase to increase cGMP, causing both arterial and venous dilation. **High-Yield Clinical Pearls for NEET-PG:** * **Nicorandil Side Effect:** A characteristic and high-yield side effect is **persistent mucosal ulceration** (oral, anal, or perianal ulcers). * **Preconditioning:** Nicorandil mimics "ischemic preconditioning," providing a cardioprotective effect during MI. * **Other K+ Channel Openers:** Minoxidil, Diazoxide (used in hypertensive emergencies/insulinoma), and Pinacidil.

Question 859: Which drug is used in Congestive Heart Failure (CHF) for the relief of congestive symptoms and restoration of cardiac performance, but does not have an inotropic action?

A. Digoxin
B. Dobutamine
C. Amrinone
D. Nebivolol (Correct Answer)

Explanation: ### Explanation **Correct Answer: D. Nebivolol** **1. Why Nebivolol is correct:** Nebivolol is a **third-generation, highly selective β1-blocker** that also possesses **vasodilatory properties** mediated through the release of **Nitric Oxide (NO)** from the vascular endothelium. In CHF, it improves cardiac performance by reducing afterload (vasodilation) and preventing the deleterious effects of chronic sympathetic overactivation (remodeling). Crucially, unlike Digoxin or Dobutamine, it does **not** have a positive inotropic action; in fact, as a beta-blocker, it is technically a negative inotrope, yet it is vital for long-term survival and symptom relief in stable CHF. **2. Why the other options are incorrect:** * **A. Digoxin:** A cardiac glycoside that inhibits the Na+/K+-ATPase pump. It is a classic **positive inotrope** used to increase the force of contraction. * **B. Dobutamine:** A β1-agonist used in acute heart failure. It is a potent **positive inotrope** that increases cAMP, leading to increased calcium influx and contractility. * **C. Amrinone (Inamrinone):** A Phosphodiesterase-3 (PDE3) inhibitor. It increases cAMP levels in the myocardium, acting as an **"Inodilator"** (positive inotrope + vasodilator). **3. Clinical Pearls for NEET-PG:** * **Beta-blockers in CHF:** Only three are proven to reduce mortality: **Metoprolol succinate, Bisoprolol, and Carvedilol.** Nebivolol is also used, particularly in elderly patients (SENIORS trial). * **Mechanism of Nebivolol:** It is the most β1-selective blocker and unique for its **L-arginine/Nitric Oxide pathway** activation. * **Inotropic vs. Lusitropic:** While inotropes increase contraction, drugs like beta-blockers improve **lusitropy** (diastolic relaxation) over time by reducing heart rate and oxygen demand. * **High-Yield Fact:** Always stabilize a CHF patient before starting beta-blockers; they are contraindicated in *acute* decompensated heart failure due to their initial negative inotropic effect.

Question 860: A patient presents with headache and profuse sweating. On examination, their blood pressure is 200/120 mm Hg. Which of the following medications should NOT be used in this scenario?

A. Nifedipine (Correct Answer)
B. Sodium nitroprusside
C. Phenoxybenzamine
D. Methyldopa

Explanation: **Explanation:** The patient presents with a **Hypertensive Emergency** (BP 200/120 mm Hg with symptoms like headache and sweating). In such scenarios, the goal is a controlled, predictable reduction in blood pressure to prevent end-organ damage or cerebral ischemia. **Why Nifedipine is the Correct Answer (Contraindicated):** Short-acting oral **Nifedipine** (capsule) is strictly contraindicated in hypertensive emergencies. It causes an unpredictable, rapid, and precipitous drop in blood pressure. This can trigger **reflex tachycardia** and "steal phenomenon," potentially leading to fatal complications such as myocardial infarction or stroke due to cerebral/coronary hypoperfusion. **Analysis of Other Options:** * **Sodium Nitroprusside:** A potent parenteral vasodilator and a traditional drug of choice for hypertensive emergencies due to its rapid onset and short duration of action, allowing for titration. * **Phenoxybenzamine:** An irreversible alpha-blocker. The clinical triad of headache, sweating, and hypertension strongly suggests **Pheochromocytoma**. In such cases, alpha-blockers are essential to control the catecholamine surge. * **Methyldopa:** A centrally acting alpha-2 agonist. While not the first line for emergencies, it is a safe and commonly used antihypertensive, particularly in pregnancy-induced hypertension. **NEET-PG High-Yield Pearls:** 1. **Drug of Choice (DOC):** For most hypertensive emergencies, **Labetalol** or **Nicardipine** are preferred. For Aortic Dissection, **Esmolol** is the DOC. 2. **Pheochromocytoma Rule:** Always give an **Alpha-blocker before a Beta-blocker** to avoid an exaggerated hypertensive crisis (unopposed alpha-stimulation). 3. **Rate of Reduction:** In emergencies, reduce Mean Arterial Pressure (MAP) by no more than **25% within the first hour** to maintain organ perfusion.

Practice by Chapter

Antihypertensive Agents

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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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