Cardiovascular Drugs — MCQs

Cardiovascular Drugs Indian Medical PG Practice Questions and MCQs

Question 471: Lipoprotein lipase is activated by which drug?

A. Atorvastatin
B. Clofibrate (Correct Answer)
C. Cholestramine
D. Nicotinic acid

Explanation: **Explanation:** The correct answer is **Clofibrate (Option B)**. **Mechanism of Action:** Clofibrate belongs to the **Fibrate** class of drugs. Fibrates act as agonists for the **Peroxisome Proliferator-Activated Receptor-alpha (PPAR-α)**, a nuclear receptor primarily expressed in the liver and skeletal muscle. Activation of PPAR-α leads to the upregulation of the **Lipoprotein Lipase (LPL)** gene. Increased LPL activity enhances the hydrolysis of triglycerides in VLDL and chylomicrons, making fibrates the drugs of choice for treating severe hypertriglyceridemia. **Analysis of Incorrect Options:** * **Atorvastatin (Option A):** This is an HMG-CoA reductase inhibitor. Its primary mechanism is inhibiting the rate-limiting step of cholesterol synthesis, leading to an upregulation of LDL receptors on hepatocytes. It does not directly activate LPL. * **Cholestyramine (Option C):** This is a Bile Acid Sequestrant. It binds bile acids in the intestine, preventing their reabsorption. This forces the liver to use systemic cholesterol to synthesize new bile acids, primarily lowering LDL levels. * **Nicotinic acid (Option D):** Also known as Niacin, it primarily acts by inhibiting lipolysis in adipose tissue (via G-protein coupled receptors) and reducing hepatic VLDL synthesis. While it may slightly increase LPL activity, its hallmark action is the inhibition of hormone-sensitive lipase. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** Fibrates are the first-line treatment for **Type IV and Type V hyperlipoproteinemia** (elevated triglycerides). * **Side Effects:** Fibrates increase the risk of **cholesterol gallstones** (by inhibiting cholesterol 7α-hydroxylase) and can cause **myopathy**, especially when combined with statins. * **PPAR-γ vs. PPAR-α:** Do not confuse them. PPAR-α is the target for Fibrates (lipids), while PPAR-γ is the target for Thiazolidinediones like Pioglitazone (diabetes).

Question 472: Which of the following conditions enhances digitalis toxicity?

A. Renal failure
B. Hyperkalemia (Correct Answer)
C. Hypercalcemia
D. Hypomagnesemia

Explanation: **Explanation** Digitalis (Digoxin) works by inhibiting the **Na⁺/K⁺-ATPase pump** on cardiac myocytes [1]. The correct answer is **Hyperkalemia** because potassium and digoxin compete for the same binding site on this pump [1]. 1. **Why Hyperkalemia is the correct answer (Mechanism):** While *hypokalemia* is the most common electrolyte trigger for toxicity (due to increased digoxin binding) [3], **hyperkalemia** is the most significant indicator of **acute, severe digitalis poisoning**. When digoxin inhibits a massive number of Na⁺/K⁺-ATPase pumps simultaneously, potassium cannot enter the cells, leading to extracellular accumulation. Therefore, a high serum potassium level in the context of digitalis overdose is a marker of "total body pump failure" and is a strong predictor of mortality. 2. **Analysis of Other Options:** * **Renal Failure:** Digoxin is primarily excreted unchanged by the kidneys. Renal impairment increases the half-life and plasma concentration, leading to toxicity. * **Hypercalcemia:** Calcium and Digoxin have synergistic effects on the heart. High calcium facilitates "calcium overload," increasing the risk of arrhythmias (Stone Heart phenomenon). * **Hypomagnesemia:** Magnesium is a cofactor for the Na⁺/K⁺-ATPase pump. Low levels sensitize the myocardium to digoxin-induced arrhythmias. **High-Yield Clinical Pearls for NEET-PG:** * **Most common arrhythmia:** Ventricular Bigeminy [2]. * **Most characteristic arrhythmia:** Atrial Tachycardia with AV Block. * **Antidote:** Digoxin Immune Fab (Digibind). * **Management of Hyperkalemia in Digoxin Toxicity:** Avoid Calcium Gluconate (may worsen toxicity); use Digibind as the definitive treatment. * **Visual Disturbance:** Xanthopsia (yellow-green halos).

Question 473: What is the half-life of Dobutamine?

A. 120 seconds (Correct Answer)
B. 200 seconds
C. 20 seconds
D. 20 minutes

Explanation: **Explanation:** **Dobutamine** is a synthetic catecholamine and a potent **$\beta_1$-selective agonist** with mild $\beta_2$ and $\alpha_1$ activity. The correct answer is **120 seconds (2 minutes)**. 1. **Why 120 seconds is correct:** Dobutamine undergoes rapid metabolism in the liver and other tissues via **COMT (Catechol-O-methyltransferase)** and conjugation. Because of this extremely rapid metabolism, its plasma half-life is approximately **2 minutes**. This necessitates administration via **continuous intravenous infusion** to maintain therapeutic levels. Its short duration of action allows for precise titration and rapid reversal of effects once the infusion is stopped. 2. **Why other options are incorrect:** * **20 seconds:** This is too short even for catecholamines; however, it is closer to the half-life of **Adenosine** (~10 seconds). * **200 seconds:** While close, it exceeds the standard pharmacological value of 2 minutes (120s) cited in standard textbooks like Goodman & Gilman or Katzung. * **20 minutes:** This is significantly longer than the actual half-life. Drugs with this half-life would not require the ultra-fine titration seen with dobutamine in ICU settings. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Primarily increases myocardial contractility (**Inotropy**) with a lesser effect on heart rate (**Chronotropy**). * **Clinical Use:** Drug of choice for **Cardiogenic Shock** and acute heart failure. * **Diagnostic Use:** Used in **Dobutamine Stress Echocardiography (DSE)** for patients unable to perform exercise stress tests. * **Adverse Effect:** Can cause tachycardia and arrhythmias; caution is required in patients with Atrial Fibrillation as it facilitates AV conduction.

Question 474: What is the mechanism of action of atorvastatin?

A. HMG-CoA synthase stimulator
B. HMG-CoA reductase stimulator
C. HMG-CoA synthase inhibitor
D. HMG-CoA reductase inhibitor (Correct Answer)

Explanation: **Explanation:** **Mechanism of Action:** Atorvastatin belongs to the class of drugs known as **Statins**. Its primary mechanism of action is the **competitive inhibition of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase**. This enzyme is the rate-limiting step in the mevalonate pathway of cholesterol synthesis. By inhibiting this enzyme, atorvastatin decreases hepatic cholesterol synthesis, which triggers an up-regulation of **LDL receptors** on the surface of hepatocytes. This results in increased clearance of LDL-cholesterol from the plasma, effectively lowering blood lipid levels. **Analysis of Incorrect Options:** * **Options A & B (Stimulators):** Atorvastatin is used to treat hyperlipidemia; stimulating enzymes involved in cholesterol production would worsen the condition. Statins are inhibitors, not activators. * **Option C (HMG-CoA synthase inhibitor):** HMG-CoA synthase is an earlier enzyme in the pathway (converting Acetoacetyl-CoA to HMG-CoA). While it is a target in some research, it is not the target for statins. Statins specifically target the **reductase** enzyme. **High-Yield Clinical Pearls for NEET-PG:** * **Pleiotropic Effects:** Beyond lowering lipids, statins stabilize atherosclerotic plaques, improve endothelial function, and have anti-inflammatory properties. * **Adverse Effects:** The most important side effects are **myopathy/rhabdomyolysis** (monitored via Creatine Kinase levels) and **hepatotoxicity** (monitored via LFTs). * **Contraindications:** Statins are strictly **Teratogenic (Category X)** and contraindicated in pregnancy. * **Timing:** While most statins are given at night (due to peak cholesterol synthesis), **Atorvastatin and Rosuvastatin** have long half-lives and can be administered at any time of day.

Question 475: Which of the following statements is WRONG about amiodarone?

A. It is the longest-acting anti-arrhythmic drug.
B. It has positive ionotropic action. (Correct Answer)
C. It contains iodine.
D. It causes pulmonary fibrosis.

Explanation: Amiodarone is a Class III anti-arrhythmic drug with a complex pharmacological profile. The statement that it has positive inotropic action is **wrong** because amiodarone actually possesses **negative inotropic effects**. It acts as a myocardial depressant and can decrease cardiac contractility, which is why it must be used with caution in patients with severe heart failure. **Explanation of Options:** * **Option B (Correct):** Amiodarone is a non-competitive antagonist of alpha and beta-adrenergic receptors and also blocks calcium channels. These properties lead to a reduction in myocardial contractility (negative inotropy) rather than an increase. * **Option A:** It is indeed the **longest-acting** anti-arrhythmic. Due to its high lipid solubility and extensive tissue distribution, its elimination half-life ranges from **3 weeks to 3 months**. * **Option C:** Amiodarone is structurally related to thyroxine and contains approximately **37% iodine** by weight. This is responsible for thyroid-related side effects (hypothyroidism or hyperthyroidism). * **Option D:** **Pulmonary fibrosis** is the most serious dose-dependent toxicity associated with long-term amiodarone use, requiring regular chest X-rays and pulmonary function tests. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Primarily blocks $K^+$ channels (Class III), but also blocks $Na^+$ (Class I), $Ca^{2+}$ (Class IV), and $\beta$-receptors (Class II). * **Side Effects Mnemonic (6 P's):** **P**ulmonary fibrosis, **P**hotodermatitis (Blue-grey skin), **P**eripheral neuropathy, **P**rolonged QT interval (though rarely causes Torsades de Pointes), **P**igmentation of cornea (corneal microdeposits), and **P**roblems with Thyroid. * **Drug of Choice:** For stable Ventricular Tachycardia and rhythm control in Atrial Fibrillation.

Question 476: Aliskiren is a:

A. Aldosterone antagonist
B. Renin/Angiotensin antagonist (Correct Answer)
C. Bradykinin analogue
D. Prostacyclin analogue

Explanation: **Explanation:** **Aliskiren** is the first and only clinically used **Direct Renin Inhibitor (DRI)**. It acts at the very first and rate-limiting step of the Renin-Angiotensin-Aldosterone System (RAAS). By directly binding to the catalytic site of renin, it prevents the conversion of Angiotensinogen to Angiotensin I. This effectively lowers levels of Angiotensin I, Angiotensin II, and Aldosterone, making it a potent **Renin/Angiotensin antagonist**. **Analysis of Incorrect Options:** * **A. Aldosterone antagonist:** These drugs (e.g., Spironolactone, Eplerenone) act at the terminal end of the RAAS by blocking mineralocorticoid receptors in the distal tubule. Aliskiren acts upstream of this. * **C. Bradykinin analogue:** ACE inhibitors (like Enalapril) prevent the breakdown of bradykinin, leading to side effects like dry cough. Aliskiren does not affect bradykinin levels, which is why it is not typically associated with a cough. * **D. Prostacyclin analogue:** These (e.g., Epoprostenol, Iloprost) are used primarily in pulmonary arterial hypertension and act via vasodilation and anti-platelet pathways, unrelated to the RAAS. **High-Yield NEET-PG Pearls:** * **Mechanism:** Direct Renin Inhibition (prevents Angiotensinogen → Angiotensin I). * **Unique Feature:** Unlike ACE inhibitors or ARBs, Aliskiren does not cause a compensatory rise in Plasma Renin Activity (PRA); instead, it decreases PRA. * **Contraindication:** It is strictly contraindicated in pregnancy (teratogenic) and should not be combined with ACEIs or ARBs in patients with diabetes or renal impairment due to the risk of hyperkalemia and hypotension (ALTITUDE trial). * **Side Effects:** Diarrhea (most common), hyperkalemia, and angioedema (rare).

Question 477: All are toxicities seen with amiodarone therapy except?

A. Pulmonary cirrhosis
B. Corneal micro-deposits
C. Cirrhosis of liver
D. Productive cough (Correct Answer)

Explanation: **Explanation:** Amiodarone is a Class III antiarrhythmic drug known for its high iodine content and exceptionally long half-life (approx. 25–60 days). It is notorious for causing multi-organ toxicities due to its accumulation in various tissues. **Why "Productive Cough" is the correct answer:** Amiodarone causes **Pulmonary Toxicity**, most commonly presenting as **interstitial lung disease or pulmonary fibrosis**. This typically manifests as a **dry, non-productive cough** and progressive dyspnea. A productive cough is usually indicative of an infectious process rather than the drug-induced inflammatory/fibrotic changes seen with amiodarone. **Analysis of Incorrect Options:** * **Pulmonary Fibrosis/Cirrhosis (Option A):** This is the most serious side effect. It occurs due to direct oxidative damage and phospholipidosis in the lungs. * **Corneal Micro-deposits (Option B):** These occur in almost 100% of patients on long-term therapy. They are usually asymptomatic and do not require drug discontinuation, though they can cause "halos" around lights. * **Cirrhosis of Liver (Option C):** Amiodarone is hepatotoxic. It can cause asymptomatic elevations in transaminases and, in rare cases, lead to chronic liver disease or cirrhosis. **High-Yield Clinical Pearls for NEET-PG:** 1. **Thyroid Dysfunction:** Amiodarone can cause both **Hypothyroidism** (Wolff-Chaikoff effect) and **Hyperthyroidism** (Jod-Basedow phenomenon) due to its 37% iodine content. 2. **Skin Changes:** Can cause a distinctive **Blue-grey skin discoloration** (Photodermatitis). 3. **Monitoring:** Baseline and periodic Chest X-rays, Pulmonary Function Tests (PFTs), Liver Function Tests (LFTs), and Thyroid Function Tests (TFTs) are mandatory. 4. **Mechanism:** Primarily blocks K+ channels but also shows Class I, II, and IV actions.

Question 478: Maximum incidence of impotence is seen with which of the following anti-hypertensive agents?

A. Calcium channel blockers (CCBs)
B. Beta blockers (Correct Answer)
C. Angiotensin II receptor blockers (ARBs)
D. Angiotensin-converting enzyme inhibitors (ACE inhibitors)

Explanation: The correct answer is **Beta blockers**. Sexual dysfunction, specifically erectile dysfunction (impotence), is a well-documented side effect of traditional antihypertensive therapy, with the highest incidence associated with **Beta blockers** and **Thiazide diuretics** [1]. **1. Why Beta Blockers?** Beta blockers (especially non-selective ones like Propranolol) cause impotence through multiple mechanisms: * **Vasoconstriction:** Blockade of $\beta_2$ receptors leads to unopposed $\alpha$-adrenergic activity, causing peripheral vasoconstriction and reduced blood flow to the corpora cavernosa. * **Central Effect:** They can decrease libido by acting on the central nervous system. * **Nitric Oxide Inhibition:** Older beta blockers may interfere with the nitric oxide-mediated vasodilation required for an erection [3]. **2. Analysis of Incorrect Options:** * **CCBs (Option A):** Generally considered neutral regarding sexual function [2]. They rarely cause impotence. * **ARBs (Option C) & ACE Inhibitors (Option D):** These drugs are either neutral or potentially **beneficial**. ARBs (like Losartan) have been shown in some studies to improve sexual function by blocking the vasoconstrictive effects of Angiotensin II in the penile vasculature. **High-Yield Clinical Pearls for NEET-PG:** * **Nebivolol:** Unlike older beta blockers, Nebivolol is a highly selective $\beta_1$ blocker that promotes **Nitric Oxide (NO)** release, making it the beta blocker with the *least* risk of impotence [3]. * **Diuretics:** Among diuretics, **Chlorthalidone** and **Thiazides** are frequently associated with impotence [1]. * **Spironolactone:** Can cause impotence and gynecomastia due to its anti-androgenic effects. * **Drug of Choice:** For a hypertensive patient concerned about sexual dysfunction, **ARBs** are the preferred choice.

Question 479: Which of the following drugs is most effective for the control of orthostatic hypotension?

A. Clonidine
B. Fludrocortisone (Correct Answer)
C. Esmolol
D. Phenylephrine

Explanation: **Explanation:** **1. Why Fludrocortisone is the Correct Answer:** Orthostatic hypotension (OH) is characterized by a significant drop in blood pressure upon standing, often due to inadequate intravascular volume or autonomic failure. **Fludrocortisone** is a potent synthetic mineralocorticoid. It works by increasing sodium and water reabsorption in the renal distal tubules, thereby expanding the **extracellular fluid (ECF) volume** and plasma volume. Additionally, it enhances the sensitivity of vascular alpha-receptors to circulating catecholamines, which improves peripheral vascular resistance. It is considered the first-line pharmacological treatment for chronic symptomatic OH. **2. Why the Other Options are Incorrect:** * **Clonidine (A):** This is a centrally acting $\alpha_2$-agonist that decreases sympathetic outflow. It is used to treat hypertension and would actually **worsen** orthostatic hypotension. * **Esmolol (C):** An ultra-short-acting $\beta_1$-selective blocker. By decreasing heart rate and contractility, it lowers blood pressure and is contraindicated in patients with OH. * **Phenylephrine (D):** While this is an $\alpha_1$-agonist that causes vasoconstriction, it is primarily used intravenously for acute hypotension (e.g., during anesthesia). Its very short half-life and risk of severe supine hypertension make it unsuitable for the long-term control of orthostatic hypotension compared to Fludrocortisone or Midodrine. **3. NEET-PG High-Yield Pearls:** * **First-line non-pharmacological management:** Increased salt/water intake and use of compression stockings. * **Midodrine:** A prodrug ($\alpha_1$-agonist) often used as an alternative or adjunct to Fludrocortisone for OH. * **Droxidopa:** A synthetic precursor of norepinephrine, also FDA-approved for neurogenic OH. * **Side effect of Fludrocortisone:** Monitor for hypokalemia, edema, and supine hypertension.

Question 480: Which antiarrhythmic drug is effective in a wide range of ventricular as well as supraventricular arrhythmias and acts mainly by prolonging the action potential?

A. Quinidine
B. Amiodarone (Correct Answer)
C. Lignocaine
D. Tocainide

Explanation: ### Explanation **Correct Option: B. Amiodarone** Amiodarone is a **Class III antiarrhythmic** agent. Its primary mechanism of action is the **blockade of potassium (K+) channels**, which leads to the prolongation of the action potential duration (APD) and the effective refractory period (ERP). While classified as Class III, Amiodarone is unique because it possesses properties of all four Vaughan-Williams classes (blocks Na+, Ca2+, and β-receptors). This "broad-spectrum" profile makes it highly effective for a wide range of arrhythmias, including both **supraventricular** (e.g., Atrial Fibrillation) and **ventricular** (e.g., Ventricular Tachycardia) arrhythmias. **Analysis of Incorrect Options:** * **A. Quinidine:** A Class IA drug. While it prolongs the action potential, it is primarily used for atrial arrhythmias and is less preferred than Amiodarone due to its significant side effect profile (e.g., Cinchonism, Torsades de pointes). * **C. Lignocaine (Lidocaine):** A Class IB drug. It **shortens** the action potential duration and is exclusively effective for **ventricular arrhythmias** (especially post-MI); it has no role in supraventricular arrhythmias. * **D. Tocainide:** Also a Class IB drug (oral analog of Lignocaine). Like Lignocaine, it is only used for ventricular arrhythmias and does not prolong the action potential. **High-Yield NEET-PG Pearls:** * **Long Half-life:** Amiodarone has an exceptionally long half-life (approx. 3–8 weeks) due to high tissue binding. * **Iodine Content:** It contains iodine, leading to thyroid dysfunction (both Hypo- and Hyperthyroidism). * **Side Effects:** Look for "Blue-grey skin discoloration," "Corneal micro-deposits," and "Pulmonary fibrosis" in clinical vignettes. * **Drug of Choice:** It is the preferred drug for rhythm control in patients with heart failure or structural heart disease.

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

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