Cardiovascular Drugs Practice Questions

Q: Tirofiban is a:

Antiplatelet drug. **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.

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

Marked changes in GIT motility. **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.

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

Quinidine. **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.

Q: Which hypolipidemic drug acts primarily by decreasing VLDL?

Fibrates. **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.

Q: What is the maintenance dose of digoxin?

0.25 mg/day. **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.

Q: Digitalis acts in Congestive Heart Failure by which mechanism?

Na+/K+ ATPase inhibition. **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).

Q: Which diuretic is appropriate for combining with ACE inhibitors?

Hydrochlorothiazide. ### 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.

Question 1

Tirofiban is a:

Accepted Answer

Antiplatelet drug

Answer

Monoclonal antibody

Answer

Anti-inflammatory drug

Answer

Antianginal drug

Question 2

Which of the following is NOT a side effect of Nimodipine?

Accepted Answer

Marked changes in GIT motility

Answer

Hypotension

Answer

Flushing

Answer

Headache

Question 3

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

Accepted Answer

Quinidine

Answer

Lignocaine

Answer

Propranolol

Answer

Adenosine

Question 4

Which hypolipidemic drug acts primarily by decreasing VLDL?

Accepted Answer

Fibrates

Answer

Nicotinic acid

Answer

Statins

Answer

Cholestyramine

Question 5

What is the maintenance dose of digoxin?

Accepted Answer

0.25 mg/day

Answer

2.5 mg/day

Answer

25 mg/day

Answer

250 mg/day

Question 6

Digitalis acts in Congestive Heart Failure by which mechanism?

Accepted Answer

Na+/K+ ATPase inhibition

Answer

Na+/K+ ATPase stimulation

Answer

Blockade of calcium channels

Answer

Increasing the refractory period of the AV node

Question 7

Digitalis does not increase which parameter of the heart?

Accepted Answer

Myocardial oxygen demand

Answer

Force of contraction

Answer

Myocardial contractility

Answer

Cardiac output

Question 8

Which of the following statements regarding ACE inhibitors is true?

Accepted Answer

Omission of a prior diuretic dose decreases the risk of postural hypotension.

Answer

ACE inhibitors inhibit the conversion of angiotensinogen to angiotensin-I.

Answer

Lisinopril is shorter acting than enalapril.

Answer

ACE inhibitors are contraindicated in diabetic patients.

Question 9

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

Accepted Answer

ACE inhibitors

Answer

Chlorthalidone

Answer

Beta blockers

Answer

Amlodipine

Question 10

Which diuretic is appropriate for combining with ACE inhibitors?

Accepted Answer

Hydrochlorothiazide

Answer

Spironolactone

Answer

Eplerenone

Answer

Amiloride

Cardiovascular Drugs — MCQs

Cardiovascular Drugs — MCQs

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