Cardiovascular Drugs Practice Questions

Q: What is the most accurate statement regarding digoxin?

Increases vagal tone and decreases AV node conduction.. **Explanation:**1. Why Option A is Correct:Digoxin exerts a potent **parasympathomimetic (vagomimetic) effect** on the heart [1]. It increases vagal tone, which slows the firing rate of the SA node and, more importantly, **prolongs the refractory period of the AV node** [1]. This decreases AV node conduction velocity (negative dromotropy) [1]. This mechanism is clinically utilized to control the ventricular rate in patients with atrial fibrillation [1].2. Why the Other Options are Incorrect:* **Option B:** While Digoxin improves symptoms and reduces the rate of hospitalization in Congestive Heart Failure (CHF), multiple trials (like the DIG trial) have shown it has **no effect on mortality** in patients with normal sinus rhythm [1].* **Option C:** Digoxin actually **shortens the action potential duration** and the refractory period in the atrial and ventricular myocardium (though it increases it in the AV node) [1]. This shortening contributes to its potential for causing arrhythmias.* **Option D:** Digoxin is **contraindicated in WPW syndrome**. By slowing AV node conduction, it may paradoxically favor conduction through the accessory pathway (Bundle of Kent), potentially leading to life-threatening ventricular tachycardia or fibrillation.**High-Yield NEET-PG Pearls:** * **Mechanism of Action:** Inhibits the **Na+/K+ ATPase pump**, leading to increased intracellular Na+, which subsequently increases intracellular Ca²+ via the Na+/Ca²+ exchanger (Positive Inotropy).* **ECG Changes:** Characterized by the **"Reverse Tick" or "Sagging" ST-segment depression** (Salvador Dali mustache sign).* **Toxicity:** Hypokalemia predisposes to toxicity. The most common arrhythmia is atrial tachycardia with AV block; the most specific is **Bidirectional Ventricular Tachycardia**.* **Antidote:** Digoxin-specific antibody fragments (DigiFab).

Q: Which of the following is NOT a centrally acting antihypertensive drug?

Trimethoprim. ### Explanation The correct answer is **D. Trimethoprim**. **1. Why Trimethoprim is the correct answer:** Trimethoprim is an **antibiotic**, not an antihypertensive. It acts as a dihydrofolate reductase inhibitor, preventing the conversion of dihydrofolic acid to tetrahydrofolic acid in bacteria. It is commonly used in combination with Sulfamethoxazole (Cotrimoxazole) for urinary tract infections and *Pneumocystis jirovecii* pneumonia. It has no mechanism of action involving the central nervous system's vasomotor centers or blood pressure regulation. **2. Analysis of Incorrect Options (Centrally Acting Drugs):** Options A, B, and C are all **central alpha-2 ($\alpha_2$) adrenergic agonists**. They work by stimulating $\alpha_2$ receptors in the nucleus tractus solitarius (NTS) of the medulla, which decreases sympathetic outflow from the brain to the heart and peripheral vasculature, thereby lowering blood pressure [1]. * **Alpha-methyl dopa:** A prodrug converted to alpha-methyl norepinephrine; it is the **drug of choice for hypertension in pregnancy** [2]. * **Clonidine:** An imidazoline derivative used for hypertension, opioid withdrawal, and ADHD. Abrupt withdrawal can cause **rebound hypertension** [1]. * **Guanabenz:** Similar to clonidine, it reduces sympathetic tone via central $\alpha_2$ stimulation. **3. NEET-PG High-Yield Pearls:** * **Side Effects:** Centrally acting drugs commonly cause sedation, dry mouth (xerostomia), and mental depression. * **Coombs Test:** Alpha-methyl dopa is associated with a positive **Direct Coombs test** and rare hemolytic anemia [1]. * **Moxonidine/Rilmenidine:** These are newer centrally acting drugs that selectively act on **Imidazoline ($I_1$) receptors**, causing fewer sedative side effects than clonidine.

Q: The drug effective for treatment as well as prophylaxis of angina pectoris is:

Isosorbide dinitrate. **Explanation:** The correct answer is **Isosorbide dinitrate (ISDN)**. This drug belongs to the organic nitrate class and is unique because it is effective for both the **acute termination** (treatment) and **long-term prevention** (prophylaxis) of angina pectoris. * **Why ISDN is correct:** ISDN can be administered via the **sublingual route** for rapid onset of action (2–5 minutes) to abort an acute attack, similar to Nitroglycerin. Additionally, it can be given **orally** for sustained prophylaxis due to its longer half-life compared to glyceryl trinitrate. Its primary mechanism is venodilation, which reduces preload and myocardial oxygen demand. **Analysis of Incorrect Options:** * **Pentaerythritol tetranitrate:** This is a long-acting nitrate with a very slow onset of action. It is used **only for prophylaxis** and is ineffective for treating an acute attack. * **Diltiazem:** While this Calcium Channel Blocker (CCB) is excellent for prophylaxis (especially in Prinzmetal angina), it is not used for the immediate termination of an acute anginal episode. * **Dipyridamole:** This drug is a phosphodiesterase inhibitor and vasodilator. It is generally **avoided** in acute angina because it can cause **"Coronary Steal Phenomenon,"** where blood is diverted away from ischemic areas to non-ischemic areas, potentially worsening the condition. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice (DOC)** for acute anginal attack: Sublingual Nitroglycerin (Glyceryl Trinitrate). * **Tolerance:** Continuous nitrate exposure leads to "tachyphylaxis." To prevent this, a **nitrate-free interval** of 8–12 hours (usually at night) is mandatory. * **Contraindication:** Never co-administer nitrates with **Sildenafil** (PDE-5 inhibitors) as it can cause life-threatening hypotension.

Q: Which antiplatelet drug inhibits the cyclo-oxygenase 1 enzyme?

Aspirin. **Explanation:** **Aspirin (Acetylsalicylic acid)** is the correct answer because it acts by **irreversibly inhibiting the Cyclo-oxygenase-1 (COX-1) enzyme** via acetylation of a serine residue. This inhibition prevents the conversion of arachidonic acid into Thromboxane A2 (TXA2), a potent platelet aggregator and vasoconstrictor. Since platelets are anucleated and cannot synthesize new enzymes, this effect lasts for the entire lifespan of the platelet (7–10 days). **Analysis of Incorrect Options:** * **Clopidogrel:** This is a P2Y12 receptor antagonist. It prevents platelet aggregation by blocking the binding of ADP to its receptor on the platelet surface. * **Tirofiban:** This belongs to the Glycoprotein IIb/IIIa (GP IIb/IIIa) inhibitors class. It blocks the "final common pathway" of platelet aggregation by preventing fibrinogen binding. * **Dipyridamole:** This is a Phosphodiesterase (PDE) inhibitor. It increases intracellular cAMP levels, which inhibits platelet aggregation and also acts as a vasodilator. **High-Yield Clinical Pearls for NEET-PG:** * **Low-dose Aspirin (75–150 mg):** Selectively inhibits COX-1 (antiplatelet effect). * **High-dose Aspirin:** Inhibits both COX-1 and COX-2 (analgesic/anti-inflammatory effect) and may inhibit PGI2 (prostacyclin) in vascular endothelium. * **Primary Prevention:** Aspirin is used in patients with a high risk of MI or stroke. * **Side Effects:** Most common is GI bleed/gastritis; most serious in children is Reye’s syndrome (if used during viral infections).

Q: All of the following are class Ic anti-arrhythmic drugs except?

Tocainide. The question asks to identify the drug that does **not** belong to Class Ic of the Vaughan-Williams classification of anti-arrhythmic drugs. **1. Why Tocainide is the Correct Answer:** Anti-arrhythmic drugs are classified based on their mechanism of action. Class I drugs are **Sodium (Na+) channel blockers**, further divided into three subclasses based on their effect on the action potential duration (APD) [2], [3]: * **Class Ia:** Moderate Na+ block; increases APD (e.g., Procainamide, Quinidine) [1], [2]. * **Class Ib:** Weak Na+ block; decreases APD (e.g., Lidocaine, **Tocainide**, Mexiletine) [1]. * **Class Ic:** Strong Na+ block; no significant effect on APD (e.g., Flecainide, Propafenone) [1]. **Tocainide** is a Class Ib agent (an oral analog of Lidocaine). Therefore, it is the exception in this list. **2. Analysis of Incorrect Options (Class Ic Agents):** * **Propafenone (Option A):** A potent Class Ic drug that also possesses weak beta-blocking activity [1]. * **Encainide (Option C):** A classic Class Ic agent (though largely replaced in clinical practice due to pro-arrhythmic risks). * **Flecainide (Option D):** The prototype Class Ic drug, often used for rhythm control in atrial fibrillation in patients without structural heart disease [1]. **3. NEET-PG High-Yield Pearls:** * **Mnemonic for Class I:** "**D**ouble **P**y **Q**uarter" (Ia: Disopyramide, Procainamide, Quinidine); "**L**etters **M**ake **T**ext" (Ib: Lidocaine, Mexiletine, Tocainide); "**E**at **F**ries **P**lease" (Ic: Encainide, Flecainide, Propafenone). * **CAST Trial Warning:** Class Ic drugs (Flecainide/Encainide) are **contraindicated post-MI** or in structural heart disease because they increase mortality due to pro-arrhythmic effects. * **Class Ic Effect:** They show "use-dependence," meaning their blocking effect is stronger at higher heart rates [2].

Q: Quinidine is used to treat which of the following conditions?

Atrial fibrillation. **Explanation:** **Quinidine** is a **Class IA antiarrhythmic** drug [1], [2]. It works by blocking open sodium (Na+) channels, which decreases the rate of rise of the action potential (Phase 0) and slows conduction velocity. Additionally, it blocks potassium (K+) channels, prolonging the action potential duration and the effective refractory period (ERP) [2]. 1. **Why Atrial Fibrillation is correct:** Due to its ability to increase the ERP and slow conduction, Quinidine is used for the **conversion and maintenance of sinus rhythm** in patients with atrial fibrillation or atrial flutter [1]. However, because it has vagolytic (antimuscarinic) effects, it can paradoxically increase AV conduction; therefore, it must be administered with an AV nodal blocking agent (like Digoxin or Beta-blockers) to prevent a rapid ventricular rate. 2. **Why other options are incorrect:** * **Hypertension:** Quinidine actually causes peripheral vasodilation (via alpha-blockade), which can lead to hypotension, but it is not a therapeutic agent for hypertension. * **Angina Pectoris:** It has no role in reducing myocardial oxygen demand or increasing supply. Beta-blockers or Calcium Channel Blockers are preferred here. * **Congestive Heart Failure (CHF):** Quinidine has a **negative inotropic effect**, which can worsen heart failure. **High-Yield Clinical Pearls for NEET-PG:** * **Cinchonism:** A classic side effect triad of tinnitus, headache, and dizziness. * **ECG Changes:** It causes **QT prolongation**, which carries a high risk of **Torsades de Pointes**. * **Drug Interaction:** Quinidine reduces the renal clearance of **Digoxin**, leading to Digoxin toxicity. * **Therapeutic Use:** While largely replaced by safer drugs, it remains a specific treatment for **Brugada Syndrome** and certain malaria strains.

Question 1

What is the most accurate statement regarding digoxin?

Accepted Answer

Increases vagal tone and decreases AV node conduction.

Answer

Decreases mortality in patients with congestive heart failure with normal sinus rhythm.

Answer

Lengthens the action potential and increases the refractoriness of the heart.

Answer

Useful in the treatment of Wolff-Parkinson-White syndrome.

Question 2

A 50-year-old diabetic patient presents with malaise. Workup reveals serum creatinine of 5.0 mg% and blood urea of 125 mg%. The Urine MICRAL test is positive. Which of the following medications would be beneficial for this patient?

Accepted Answer

Diuretics

Answer

Cardio-selective beta blocker

Answer

ACE inhibitor

Answer

Amiodarone

Question 3

Which of the following describes the mechanism of action of levosimendan?

Accepted Answer

Potassium channel opener

Answer

Sodium channel opener

Answer

Beta blocker

Answer

Beta-1 agonist

Question 4

Which of the following is NOT a centrally acting antihypertensive drug?

Accepted Answer

Trimethoprim

Answer

Alpha methyl dopa

Answer

Clonidine

Answer

Guanabenz

Question 5

The drug effective for treatment as well as prophylaxis of angina pectoris is:

Accepted Answer

Isosorbide dinitrate

Answer

Pentaerythritol tetranitrate

Answer

Diltiazem

Answer

Dipyridamole

Question 6

Which antiplatelet drug inhibits the cyclo-oxygenase 1 enzyme?

Accepted Answer

Aspirin

Answer

Clopidogrel

Answer

Tirofiban

Answer

Dipyridamole

Question 7

Which of the following calcium channel blockers has a predominant peripheral action?

Accepted Answer

Nifedipine

Answer

Verapamil

Answer

Diltiazem

Answer

Nor-verapamil

Question 8

Which drug used in the treatment of peripheral vascular disease acts by increasing the flexibility of the RBC membrane and improving microcirculation?

Accepted Answer

Pentoxifylline

Answer

Cyclandelate

Answer

Xanhinol nicotinate

Answer

Cilostazole

Question 9

All of the following are class Ic anti-arrhythmic drugs except?

Accepted Answer

Tocainide

Answer

Propafenone

Answer

Enacainide

Answer

Flecainide

Question 10

Quinidine is used to treat which of the following conditions?

Accepted Answer

Atrial fibrillation

Answer

Hypertension

Answer

Angina pectoris

Answer

Congestive heart failure

Cardiovascular Drugs — MCQs

Cardiovascular Drugs — MCQs

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