Cardiovascular Drugs — MCQs

Cardiovascular Drugs Indian Medical PG Practice Questions and MCQs

Question 891: Tirofiban is a:

A. Monoclonal antibody
B. Antiplatelet drug (Correct Answer)
C. Anti-inflammatory drug
D. Antianginal drug

Explanation: **Explanation:** **Tirofiban** is a non-peptide, small-molecule reversible antagonist of the **Glycoprotein (GP) IIb/IIIa receptor** found on the surface of platelets [1], [2]. 1. **Why Option B is Correct:** The GP IIb/IIIa receptor is the "final common pathway" for platelet aggregation [4]. When activated, it binds to fibrinogen, cross-linking platelets to form a plug [4]. By blocking this receptor, Tirofiban prevents platelet aggregation regardless of the initial stimulus (ADP, Thromboxane A2, or Collagen) [3]. Therefore, it is classified as a potent **antiplatelet drug** (specifically a parenteral GP IIb/IIIa inhibitor) [1]. 2. **Why Other Options are Incorrect:** * **Option A:** While Abciximab (another GP IIb/IIIa inhibitor) is a monoclonal antibody, **Tirofiban and Eptifibatide are non-antibody molecules** [1], [3]. * **Option C:** Tirofiban has no significant effect on the arachidonic acid pathway or systemic inflammation; its action is specific to primary hemostasis. * **Option D:** While used in the management of Unstable Angina, it is not an "antianginal" drug (like Nitrates or Beta-blockers) because it doesn't reduce myocardial oxygen demand; it prevents coronary thrombus progression. **High-Yield Clinical Pearls for NEET-PG:** * **Administration:** Given only via **Intravenous (IV)** route [2], [3]. * **Indications:** Primarily used in **Acute Coronary Syndrome (ACS)**, specifically Unstable Angina and NSTEMI, and during **Percutaneous Coronary Intervention (PCI)** to prevent thrombotic complications. * **Side Effects:** The most significant adverse effect is **bleeding** and occasionally acute thrombocytopenia [1]. * **Elimination:** It is primarily cleared by the kidneys; dose adjustment is required in renal failure.

Question 892: Which of the following is NOT a side effect of Nimodipine?

A. Hypotension
B. Flushing
C. Headache
D. Marked changes in GIT motility (Correct Answer)

Explanation: **Explanation:** **Nimodipine** is a second-generation dihydropyridine (DHP) calcium channel blocker (CCB). Its primary mechanism involves blocking L-type calcium channels, leading to smooth muscle relaxation. **Why "Marked changes in GIT motility" is the correct answer:** While non-dihydropyridines like Verapamil are notorious for causing significant constipation (due to inhibition of calcium-dependent contractions in the colonic muscularis), **dihydropyridines like Nimodipine have minimal effect on gastrointestinal motility.** Nimodipine is highly lipid-soluble and possesses a unique cerebrovascular selectivity, making it the drug of choice for preventing vasospasm following **Subarachnoid Hemorrhage (SAH)**. **Analysis of Incorrect Options:** * **A. Hypotension:** Like all DHPs, Nimodipine causes peripheral vasodilation. Although it is more selective for cerebral vessels, systemic vasodilation can still occur, leading to a drop in blood pressure. * **B. Flushing:** This is a common side effect of the DHP class resulting from cutaneous vasodilation. * **C. Headache:** Vasodilation of meningeal vessels is a frequent side effect of CCBs, often presenting as a throbbing headache. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** Nimodipine is the standard of care to improve neurological outcomes in patients with **Aneurysmal Subarachnoid Hemorrhage**. * **Selectivity:** It is highly lipophilic, allowing it to cross the blood-brain barrier effectively. * **Verapamil vs. DHPs:** Remember that **Verapamil** is the CCB most commonly associated with **constipation** (GIT motility changes). * **DHP Side Effect Profile:** Think of the "Vasodilatory Triad": Headache, Flushing, and Ankle Edema.

Question 893: Which of the following antiarrhythmic drugs can decrease the slope of Phase 0 and prolong the action potential duration?

A. Lignocaine
B. Propranolol
C. Quinidine (Correct Answer)
D. Adenosine

Explanation: **Explanation:** The question describes the characteristic electrophysiological profile of **Class IA antiarrhythmics**. **1. Why Quinidine is Correct:** Quinidine belongs to **Vaughan Williams Class IA**. Its mechanism involves: * **Sodium Channel Blockade (Phase 0):** By blocking fast inward $Na^+$ channels, it decreases the rate of depolarization (slope of Phase 0). * **Potassium Channel Blockade (Phase 3):** It inhibits outward $K^+$ currents, which delays repolarization, thereby **prolonging the Action Potential Duration (APD)** and the Effective Refractory Period (ERP). **2. Why the other options are incorrect:** * **Lignocaine (Class IB):** While it blocks $Na^+$ channels, it typically **shortens** or has no effect on the APD. It preferentially binds to channels in the inactivated state (common in ischemic tissue). * **Propranolol (Class II):** A Beta-blocker that acts primarily by decreasing the slope of **Phase 4** (pacemaker potential) in the SA node. It does not significantly affect Phase 0 of the ventricular action potential. * **Adenosine:** Acts via $A_1$ receptors to increase $K^+$ conductance and decrease $Ca^{2+}$ current in the AV node. It causes hyperpolarization and is used for terminating PSVT, not for modifying ventricular APD in this manner. **High-Yield NEET-PG Pearls:** * **Class IA Mnemonic:** "**P**yramid **Q**ueen **D**isappears" (**P**rocainamide, **Q**uinidine, **D**isopyramide). All three increase APD and QT interval. * **Side Effect:** Quinidine can cause **Cinchonism** (tinnitus, vertigo) and **Torsades de Pointes** due to QT prolongation. * **Drug Interaction:** Quinidine increases plasma levels of **Digoxin** by displacing it from tissue binding sites and reducing renal clearance.

Question 894: Which hypolipidemic drug acts primarily by decreasing VLDL?

A. Fibrates (Correct Answer)
B. Nicotinic acid
C. Statins
D. Cholestyramine

Explanation: **Explanation:** **Fibrates (e.g., Fenofibrate, Gemfibrozil)** are the correct answer because their primary mechanism of action is the activation of **Peroxisome Proliferator-Activated Receptor-alpha (PPAR-α)**. This leads to an increase in the synthesis of Lipoprotein Lipase (LPL), which enhances the clearance of triglyceride-rich lipoproteins. Consequently, fibrates significantly decrease the production and increase the catabolism of **VLDL** (Very Low-Density Lipoprotein), making them the drugs of choice for severe hypertriglyceridemia. **Analysis of Incorrect Options:** * **Nicotinic Acid (Niacin):** While it reduces VLDL and LDL, its most distinctive clinical effect is being the most potent agent for **increasing HDL** levels. It acts by inhibiting adipose tissue lipolysis. * **Statins (HMG-CoA Reductase Inhibitors):** These are the first-line drugs for hypercholesterolemia. Their primary action is decreasing **LDL** by inhibiting cholesterol synthesis and upregulating LDL receptors. * **Cholestyramine (Bile Acid Sequestrants):** These act locally in the intestine to prevent bile acid reabsorption. This forces the liver to use more cholesterol to synthesize new bile acids, primarily resulting in a decrease in **LDL**. **NEET-PG High-Yield Pearls:** * **Drug of choice for Hypertriglyceridemia:** Fibrates. * **Drug of choice for Hypercholesterolemia:** Statins. * **Side Effect Alert:** Combining Statins and Fibrates (especially Gemfibrozil) significantly increases the risk of **myopathy and rhabdomyolysis** due to competition for glucuronidation pathways. * **Fenofibrate** is the preferred fibrate to use with statins as it has a lower risk of causing myopathy.

Question 895: What is the maintenance dose of digoxin?

A. 0.25 mg/day (Correct Answer)
B. 2.5 mg/day
C. 25 mg/day
D. 250 mg/day

Explanation: **Explanation:** Digoxin is a cardiac glycoside with a **narrow therapeutic index**, meaning the difference between a therapeutic dose and a toxic dose is very small. **1. Why Option A is correct:** The standard maintenance dose of digoxin for an adult with normal renal function is **0.125 to 0.25 mg per day**. This dose is sufficient to maintain steady-state plasma concentrations (typically 0.5–2.0 ng/mL) required to inhibit the Na+/K+-ATPase pump, thereby increasing intracellular calcium and improving cardiac contractility (in heart failure) or controlling ventricular rate (in atrial fibrillation). **2. Why the other options are incorrect:** * **Option B (2.5 mg/day):** This is 10 times the standard dose. Such a dose would rapidly lead to severe digitalis toxicity, manifesting as arrhythmias, xanthopsia (yellow vision), and gastrointestinal distress. * **Options C and D (25 mg and 250 mg):** These are massive, lethal doses. Digoxin is measured in **micrograms (mcg)** or small fractions of a milligram. Doses in these ranges would cause immediate cardiac arrest. **3. High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Inhibits Na+/K+-ATPase pump $\rightarrow$ increases intracellular Na+ $\rightarrow$ slows Na+/Ca2+ exchanger $\rightarrow$ increases intracellular Ca2+ (Positive inotropy). * **Vagal Effect:** Digoxin increases vagal tone, which slows conduction through the AV node (Negative dromotropy), making it useful in atrial fibrillation. * **Toxicity Predisposition:** **Hypokalemia** is the most common trigger for digoxin toxicity because K+ and digoxin compete for the same binding site on the Na+/K+-ATPase pump. Hypomagnesemia and hypercalcemia also increase toxicity risk. * **Antidote:** Digoxin-specific antibody fragments (**DigiFab/Digibind**). * **ECG Changes:** Characterized by a "reverse tick" sign or "sagging" ST-segment depression.

Question 896: Digitalis acts in Congestive Heart Failure by which mechanism?

A. Na+/K+ ATPase inhibition (Correct Answer)
B. Na+/K+ ATPase stimulation
C. Blockade of calcium channels
D. Increasing the refractory period of the AV node

Explanation: **Explanation:** **Mechanism of Action (Correct Option A):** Digitalis (Digoxin) acts by reversibly inhibiting the **Na+/K+ ATPase pump** located on the sarcolemma of cardiac myocytes [1]. This inhibition leads to an accumulation of intracellular sodium ($Na^+$). The increased intracellular $Na^+$ reduces the concentration gradient that drives the **Na+/Ca2+ exchanger (NCX)** [2]. Consequently, the extrusion of calcium ($Ca^{2+}$) from the cell is decreased, leading to higher intracellular $Ca^{2+}$ levels [2]. This excess calcium is sequestered into the Sarcoplasmic Reticulum, resulting in increased calcium release during subsequent depolarizations, which enhances myocardial contractility (**Positive Inotropic Effect**) [1]. **Analysis of Incorrect Options:** * **B. Na+/K+ ATPase stimulation:** This would decrease intracellular sodium and calcium, leading to a negative inotropic effect, which is the opposite of the desired therapeutic goal in heart failure. * **C. Blockade of calcium channels:** Calcium channel blockers (like Verapamil) decrease contractility (negative inotropy) and are generally avoided in systolic heart failure. * **D. Increasing the refractory period of the AV node:** While Digoxin *does* do this via vagomimetic action, this is its mechanism for controlling rate in **Atrial Fibrillation**, not its primary mechanism for improving cardiac output in **Congestive Heart Failure** [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Electrolyte sensitivity:** Hypokalemia, hypomagnesemia, and hypercalcemia predispose to Digoxin toxicity [1]. * **ECG Changes:** The earliest sign of toxicity is often PVCs; the most characteristic sign is the "reverse tick" or "sagging" ST-segment depression. * **Drug of Choice:** Digoxin is the drug of choice for Heart Failure with concomitant Atrial Fibrillation. * **Antidote:** Digibind (Digoxin-specific Fab fragments).

Question 897: Digitalis does not increase which parameter of the heart?

A. Force of contraction
B. Myocardial contractility
C. Myocardial oxygen demand (Correct Answer)
D. Cardiac output

Explanation: ### Explanation Digitalis (Digoxin) is a cardiac glycoside primarily used for its positive inotropic and negative chronotropic effects. The correct answer is **C. Myocardial oxygen demand**, as Digitalis is unique among inotropes for its ability to improve cardiac performance without increasing overall oxygen consumption in a failing heart. #### Why Myocardial Oxygen Demand is the Correct Answer: In a healthy heart, an increase in contractility usually increases oxygen demand. However, in a **failing heart**, Digitalis reduces the heart rate (negative chronotropy) and decreases ventricular wall tension (by reducing end-diastolic volume and pressure through better emptying). These two factors—reduced heart rate and reduced wall tension—offset the oxygen cost of increased contractility. Consequently, the net myocardial oxygen demand remains unchanged or even decreases. #### Why Other Options are Incorrect: * **A & B. Force of contraction / Myocardial contractility:** Digitalis inhibits the **Na⁺/K⁺-ATPase pump**, leading to an increase in intracellular Na⁺. This slows the Na⁺/Ca²⁺ exchanger, resulting in increased intracellular Ca²⁺ available for contraction. Thus, it is a potent **positive inotrope**. * **D. Cardiac output:** By increasing the force of contraction (stroke volume) and improving the efficiency of the failing ventricle, Digitalis significantly increases the total cardiac output. #### High-Yield Clinical Pearls for NEET-PG: * **Mechanism:** Inhibition of Na⁺/K⁺-ATPase pump (the "Digitalis receptor"). * **ECG Changes:** Characterized by the **"Reverse Tick" sign** or "Sagging" ST-segment depression. * **Electrolyte Interactions:** **Hypokalemia**, hypomagnesemia, and hypercalcemia predispose a patient to Digitalis toxicity. * **Drug of Choice:** Digoxin is used in Heart Failure with **Atrial Fibrillation** due to its ability to decrease AV node conduction (vagomimetic effect). * **Antidote:** Digibind (Digoxin-specific Fab fragments).

Question 898: Which of the following statements regarding ACE inhibitors is true?

A. ACE inhibitors inhibit the conversion of angiotensinogen to angiotensin-I.
B. Omission of a prior diuretic dose decreases the risk of postural hypotension. (Correct Answer)
C. Lisinopril is shorter acting than enalapril.
D. ACE inhibitors are contraindicated in diabetic patients.

Explanation: **Explanation:** **1. Why Option B is Correct:** The most significant side effect of the first dose of an ACE inhibitor (ACEi) is **"First-dose hypotension."** This occurs because ACE inhibitors cause a rapid fall in Angiotensin II levels, leading to vasodilation. Patients already on **diuretics** are often volume-depleted and have a highly activated Renin-Angiotensin-Aldosterone System (RAAS). In these patients, the blood pressure is heavily dependent on Angiotensin II; blocking it causes a precipitous drop in BP. Therefore, **withdrawing diuretics 24–48 hours before** starting an ACEi significantly reduces the risk of severe postural hypotension. **2. Why the Other Options are Incorrect:** * **Option A:** ACE inhibitors inhibit the **Angiotensin-Converting Enzyme**, which converts Angiotensin I to Angiotensin II. The conversion of Angiotensinogen to Angiotensin I is inhibited by **Aliskiren** (a direct renin inhibitor). * **Option C:** **Lisinopril** is a long-acting ACE inhibitor with a half-life that allows for once-daily dosing. In contrast, **Enalapril** (a prodrug) has a shorter duration of action compared to Lisinopril. * **Option D:** ACE inhibitors are actually the **drugs of choice** for hypertensive diabetic patients because they provide **nephroprotection** by dilating the efferent arteriole, thereby reducing intraglomerular pressure and slowing the progression of diabetic nephropathy. **High-Yield Clinical Pearls for NEET-PG:** * **Teratogenicity:** ACEis are strictly contraindicated in pregnancy (cause fetal renal anomalies/hypoplasia). * **Side Effects Mnemonic (CAPTOPRIL):** **C**ough (due to Bradykinin), **A**ngioedema, **P**roteinuria, **T**aste changes, **O**thostatic hypotension, **P**regnancy contraindication, **R**enal artery stenosis (bilateral) contraindication, **I**ncreased potassium (Hyperkalemia), **L**eukopenia. * **Prodrugs:** All ACE inhibitors are prodrugs **except Lisinopril and Captopril.**

Question 899: Spironolactone should not be administered with which of the following drug classes?

A. Chlorthalidone
B. Beta blockers
C. ACE inhibitors (Correct Answer)
D. Amlodipine

Explanation: **Explanation:** The correct answer is **ACE inhibitors (Option C)**. **1. Why ACE inhibitors are contraindicated with Spironolactone:** Spironolactone is a potassium-sparing diuretic that acts as an aldosterone antagonist in the distal convoluted tubule and collecting duct. ACE inhibitors (e.g., Enalapril, Ramipril) decrease the production of Angiotensin II, which in turn leads to a reduction in aldosterone secretion. Since both drugs inhibit the action/secretion of aldosterone, their combined use significantly impairs the renal excretion of potassium. This synergistic effect leads to a high risk of **life-threatening hyperkalemia**. **2. Analysis of Incorrect Options:** * **A. Chlorthalidone:** This is a thiazide-like diuretic. Thiazides cause potassium depletion (hypokalemia). Combining them with Spironolactone is often clinically beneficial to balance potassium levels and enhance diuresis. * **B. Beta blockers:** While some beta-blockers can slightly increase potassium levels by inhibiting renin release, they are not contraindicated. In fact, the combination of Beta-blockers, ACE inhibitors, and Spironolactone is the "triple therapy" cornerstone for Heart Failure with Reduced Ejection Fraction (HFrEF), provided potassium levels are strictly monitored. * **D. Amlodipine:** This is a Calcium Channel Blocker (CCB) that does not significantly affect serum potassium levels. **3. High-Yield Clinical Pearls for NEET-PG:** * **Eplerenone** is a more selective aldosterone antagonist than Spironolactone and has fewer anti-androgenic side effects (like gynecomastia). * **Monitoring:** When prescribing Spironolactone with ACE inhibitors or ARBs, serum potassium and creatinine must be checked within 1 week of initiation. * **Contraindication:** Avoid this combination if serum potassium is **>5.0 mEq/L** or serum creatinine is **>2.5 mg/dL**. * **Drug of Choice:** Spironolactone is the drug of choice for **Primary Hyperaldosteronism (Conn’s Syndrome)** and edema associated with **Liver Cirrhosis**.

Question 900: Which diuretic is appropriate for combining with ACE inhibitors?

A. Spironolactone
B. Eplerenone
C. Hydrochlorothiazide (Correct Answer)
D. Amiloride

Explanation: ### Explanation The correct answer is **Hydrochlorothiazide (Option C)**. **1. Why Hydrochlorothiazide is correct:** The primary rationale for combining ACE inhibitors (ACEIs) with Thiazide diuretics (like Hydrochlorothiazide) is the **synergistic effect** on blood pressure and the **balancing of serum potassium levels**. * **Synergy:** ACEIs block the Renin-Angiotensin-Aldosterone System (RAAS), which prevents the compensatory rise in aldosterone typically caused by diuretics. * **Potassium Homeostasis:** ACEIs tend to cause **hyperkalemia** (by reducing aldosterone-mediated K+ excretion). Conversely, Thiazides cause **hypokalemia** (by increasing distal delivery of Na+, leading to K+ loss). When used together, they neutralize each other's effect on potassium, maintaining electrolyte stability. **2. Why the other options are incorrect:** * **Options A (Spironolactone) and B (Eplerenone):** These are Potassium-Sparing Diuretics (Aldosterone Antagonists). Combining them with ACEIs significantly increases the risk of **severe, life-threatening hyperkalemia**, as both drug classes promote potassium retention. * **Option D (Amiloride):** This is an Epithelial Sodium Channel (ENaC) blocker, another type of potassium-sparing diuretic. Like Spironolactone, it carries a high risk of hyperkalemia when combined with ACEIs. **3. NEET-PG High-Yield Pearls:** * **First-line combination:** ACEI + Thiazide is a preferred combination for hypertension according to JNC guidelines. * **Metabolic benefit:** ACEIs may improve insulin sensitivity, potentially offsetting the mild hyperglycemic effect of Thiazides. * **Contraindication:** Never combine ACEIs with ARBs (e.g., Telmisartan) or Direct Renin Inhibitors (Aliskiren) due to the risk of renal failure and hyperkalemia. * **Monitoring:** Always monitor serum creatinine and potassium levels within 1–2 weeks of starting this combination.

Practice by Chapter

Antihypertensive Agents

Practice Questions

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

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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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