Cardiovascular Drugs Practice Questions

Q: What is the drug of choice for torsades de pointes?

Magnesium sulphate. **Explanation:** **Torsades de Pointes (TdP)** is a specific form of polymorphic ventricular tachycardia characterized by a "twisting of points" around the isoelectric line, typically occurring in the setting of a prolonged QT interval. **Why Magnesium Sulphate (MgSO₄) is the Correct Answer:** Magnesium sulphate is the **drug of choice** for both the treatment and prevention of recurrences of TdP, regardless of the patient's baseline magnesium levels. It works by blocking **L-type calcium channels**, which suppresses the early after-depolarizations (EADs) that trigger the arrhythmia. It also stabilizes the cardiac membrane without significantly shortening the QT interval itself. **Analysis of Incorrect Options:** * **A. Terfenadine:** This is a non-sedating antihistamine that was withdrawn from the market because it actually **causes** TdP by blocking hERG potassium channels (leading to QT prolongation), especially when taken with CYP3A4 inhibitors. * **B. Quinidine:** A Class IA antiarrhythmic known for causing "Quinidine Syncope." It blocks potassium channels, prolongs the QT interval, and is a notorious **precipitant** of TdP. * **C. Isoprenaline:** While it can be used to increase heart rate (overdrive pacing) to shorten the QT interval in bradycardia-dependent TdP, it is a second-line agent and not the initial drug of choice. **NEET-PG High-Yield Pearls:** * **Dose:** 2 grams IV bolus over 1–2 minutes. * **Congenital Long QT Syndromes:** For Jervell and Lange-Nielsen or Romano-Ward syndromes, **Beta-blockers** (like Propranolol) are the mainstay of chronic management, but MgSO₄ remains the acute treatment for TdP episodes. * **Avoid:** Class IA (Quinidine, Procainamide) and Class III (Sotalol, Amiodarone) antiarrhythmics, as they worsen QT prolongation.

Q: Why is glyceryl trinitrate (GTN) administered sublingually?

To avoid first-pass metabolism. Explanation:1. Why Option A is Correct:Glyceryl Trinitrate (GTN) undergoes extensive high first-pass metabolism in the liver (nearly 90-100% extraction ratio) [1, 2]. If taken orally, the drug is absorbed from the GI tract into the portal circulation and metabolized by hepatic enzymes before reaching the systemic circulation, rendering it ineffective [1, 2]. The sublingual route allows the drug to be absorbed directly through the oral mucosa into the systemic venous circulation (via the superior vena cava), bypassing the liver and ensuring high bioavailability [1].2. Why Other Options are Incorrect:Option B: While sublingual administration does provide a rapid onset of action (1–3 minutes) [2], the primary pharmacological reason for choosing this route over the oral route is the avoidance of metabolic degradation [1]. Rapid onset is a clinical benefit, but avoiding first-pass metabolism is the pharmacokinetic necessity.Option C: GTN is not inherently a gastric irritant; the route is chosen for pharmacokinetic stability, not to protect the stomach lining.Option D: Sublingual administration actually increases the risk of systemic side effects (like throbbing headache and hypotension) because it achieves higher plasma concentrations more quickly than oral administration.3. NEET-PG High-Yield Pearls:Drug of Choice: Sublingual GTN is the drug of choice for acute anginal attacks.Storage: GTN is volatile and light-sensitive; it must be stored in tightly closed, dark glass containers.Mechanism: It acts by releasing Nitric Oxide (NO), which increases cGMP, leading to dephosphorylation of myosin light chains and resulting in venodilation (reducing preload).Other drugs with high first-pass metabolism: Propranolol, Lidocaine, Salbutamol, and Morphine.

Q: Cardiac glycosides are obtained from which plant source?

Strophanthus gratus.. **Explanation:** **Cardiac glycosides** (like Digoxin and Ouabain) are naturally occurring compounds used to increase myocardial contractility. They are primarily derived from two plant genera: **Digitalis** (Foxglove) and **Strophanthus** [1], [2]. * **Why Option B is correct:** **Strophanthus gratus** is the primary source of **G-strophanthin**, also known as **Ouabain** [4]. Another species, *Strophanthus kombe*, provides K-strophanthin. These glycosides inhibit the Na+/K+-ATPase pump, leading to an increase in intracellular calcium and improved cardiac output in heart failure [2], [3]. **Analysis of Incorrect Options:** * **A. Rauwolfia serpentina:** Known as Indian Snakeroot, it is the source of **Reserpine**. It was historically used as an antihypertensive and antipsychotic by depleting catecholamines, not as a cardiac glycoside. * **C. Ricinus communis:** This is the source of **Castor oil** (a stimulant laxative) and the potent toxin **Ricin**. It has no therapeutic role in cardiac contractility. * **D. Atropa belladonna:** Known as Deadly Nightshade, it is a source of **Atropine**. While it affects the heart (increasing heart rate by blocking M2 receptors), it is an anticholinergic, not a cardiac glycoside. **High-Yield Clinical Pearls for NEET-PG:** * **Digoxin** is derived from *Digitalis lanata* (Grecian foxglove). * **Digitoxin** is derived from *Digitalis purpurea* (Purple foxglove) [2]. * **Mechanism:** Inhibition of Na+/K+-ATPase → Increased intracellular Na+ → Decreased Na+/Ca2+ exchange → Increased intracellular Ca2+ (**Positive Inotropy**) [3]. * **ECG Changes:** Characterized by the "reverse tick" or "sagging" ST-segment depression (Salvador Dali sign).

Q: Which of the following possesses the highest efficacy to increase HDL cholesterol?

Nicotinic acid. **Explanation:** **Nicotinic Acid (Niacin)** is the correct answer because it is the most potent agent currently available for increasing HDL cholesterol levels. It typically raises HDL by **15% to 35%**. It achieves this by inhibiting the hepatic breakdown of Apolipoprotein A-I (the primary protein component of HDL), thereby increasing its half-life and circulating levels. Additionally, Niacin inhibits the peripheral mobilization of free fatty acids, reducing VLDL and LDL synthesis. **Analysis of Incorrect Options:** * **Gemfibrozil (Fibrates):** While Fibrates are the drugs of choice for reducing **Triglycerides**, their effect on HDL is modest (usually a 10–15% increase), making them less efficacious than Niacin for this specific purpose. * **Atorvastatin (Statins):** Statins are the gold standard for lowering **LDL cholesterol**. Although they do increase HDL, the effect is minimal (5–10%). * **Enoic acid:** This is likely a distractor referring to fatty acids (like Eicosapentaenoic acid/Omega-3). These are primarily used to lower triglycerides and have negligible effects on raising HDL. **NEET-PG High-Yield Pearls:** * **Side Effects of Niacin:** The most common side effect is **cutaneous flushing** (mediated by Prostaglandin D2/E2), which can be minimized by taking **Aspirin** 30 minutes prior. It can also cause hyperuricemia (precipitating gout) and hyperglycemia. * **Mechanism of Fibrates:** They act as **PPAR-α agonists**, increasing the activity of Lipoprotein Lipase (LPL). * **Drug of Choice Summary:** * To lower LDL: Statins. * To lower Triglycerides: Fibrates. * To raise HDL: Niacin.

Q: Nitroglycerine can be administered by all of the following routes except?

Intramuscular. **Explanation:** Nitroglycerine (Glyceryl Trinitrate - GTN) is a potent vasodilator used primarily for angina pectoris. The correct answer is **Intramuscular (C)** because this route is not used clinically for GTN. Intramuscular injections are avoided due to unpredictable absorption rates and the risk of local tissue irritation, especially when more efficient and titratable routes are available. **Analysis of Options:** * **Oral (A):** GTN can be given orally (sustained-release tablets), but it undergoes **extensive first-pass metabolism** in the liver (bioavailability <1%). Therefore, oral doses must be significantly higher than sublingual doses to be effective. * **Sublingual (B):** This is the **route of choice for acute anginal attacks**. It bypasses the liver (avoiding first-pass metabolism), ensuring rapid onset of action (1–3 minutes). * **Intravenous (D):** Used in **emergency settings** such as unstable angina, acute heart failure, or hypertensive emergencies. It allows for precise titration and immediate effect. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** GTN is a prodrug that releases **Nitric Oxide (NO)**, increasing cGMP and causing smooth muscle relaxation (primarily venodilation, reducing preload). * **Storage:** GTN is volatile and light-sensitive; it must be stored in **dark glass containers** with tight metal caps. * **Tolerance:** Continuous use leads to "Nitrate Tolerance" (depletion of free sulfhydryl groups). A **nitrate-free interval** of 8–12 hours (usually at night) is required to restore sensitivity. * **Contraindication:** Never co-administer with **Sildenafil** (PDE-5 inhibitors) as it can cause life-threatening hypotension.

Q: In the treatment of shock, why is Dobutamine preferred over Dopamine?

All the above.. **Explanation:** Dobutamine is a synthetic sympathomimetic that primarily acts as a **$\beta_1$-selective agonist**, making it an ideal inotropic agent in cardiogenic shock. While both drugs increase cardiac output, Dobutamine offers several clinical advantages over Dopamine: 1. **Fewer Arrhythmias (Option A):** Dopamine triggers a significant release of endogenous norepinephrine and has a stronger effect on $\alpha$ and $\beta$ receptors at higher doses, leading to a higher incidence of tachyarrhythmias compared to Dobutamine. 2. **Renal Vasodilation (Option B):** While Dopamine at low doses ("renal dose") acts on $D_1$ receptors to cause vasodilation, this effect is often unpredictable in shock states and can lead to a "steal phenomenon." Dobutamine maintains systemic perfusion more steadily without the complex dose-dependent shifts (Dopaminergic $\rightarrow$ Beta $\rightarrow$ Alpha) seen with Dopamine. 3. **Coronary Vasoconstriction (Option C):** At the high doses often required in shock, Dopamine’s $\alpha_1$-agonist activity causes peripheral and coronary vasoconstriction, increasing afterload and myocardial oxygen demand. Dobutamine, through its mild $\beta_2$ activity, tends to decrease systemic vascular resistance (afterload), improving stroke volume without significant coronary constriction. **Clinical Pearls for NEET-PG:** * **Drug of Choice:** Dobutamine is the preferred inotrope for **Cardiogenic Shock** and is used in **Stress Echocardiography**. * **Dopamine Limitation:** It is no longer the first-line agent for shock due to the risk of arrhythmias and increased mortality in certain subsets of patients. * **Key Side Effect:** The most common side effect of Dobutamine is tachycardia. * **Vascular Effect:** Unlike Dopamine, Dobutamine is a **"Inodilator"** (Inotrope + Vasodilator).

Q: Which of the following drugs does not cause bradycardia?

Hydralazine. The correct answer is **Hydralazine** because it is a potent direct-acting arteriolar vasodilator [1, 2]. When systemic vascular resistance drops rapidly, the body compensates via the baroreceptor reflex. This triggers a significant increase in sympathetic outflow, leading to **reflex tachycardia**, not bradycardia [3]. In clinical practice, hydralazine is often co-administered with a beta-blocker to counteract this compensatory tachycardia [3]. **Analysis of Incorrect Options:** * **Propranolol:** A non-selective beta-blocker that decreases heart rate by blocking $\beta_1$ receptors in the SA node. It is a classic cause of bradycardia [4]. * **Clonidine:** An $\alpha_2$-adrenergic agonist that acts centrally to decrease sympathetic outflow and increase vagal tone, leading to a reduction in heart rate. * **Reserpine:** An alkaloid that depletes catecholamines (norepinephrine) from peripheral sympathetic nerve endings and the CNS. The loss of sympathetic stimulation to the heart results in bradycardia. **High-Yield Clinical Pearls for NEET-PG:** * **Vasodilator Paradox:** Direct vasodilators (Hydralazine, Minoxidil, Nifedipine) typically cause reflex tachycardia [3]. In contrast, centrally acting drugs (Clonidine, Methyldopa) and sympatholytics (Reserpine, Beta-blockers) cause bradycardia. * **Hydralazine Side Effects:** Apart from tachycardia, it is famously associated with **Drug-Induced Lupus Erythematosus (DILE)**, especially in "slow acetylators." * **Clinical Use:** Hydralazine is a preferred drug for managing hypertension in pregnancy (alongside Labetalol and Methyldopa).

Question 1

A male patient presents with headache, profuse sweating, and palpitations with a blood pressure of 180/120 mm Hg. What is the drug of choice?

Accepted Answer

Labetalol

Answer

Nifedipine

Answer

Prazosin

Answer

Phenoxybenzamine

Question 2

What is the drug of choice for torsades de pointes?

Accepted Answer

Magnesium sulphate

Answer

Terfenadine

Answer

Quinidine

Answer

Isoprenaline

Question 3

Why is glyceryl trinitrate (GTN) administered sublingually?

Accepted Answer

To avoid first-pass metabolism

Answer

For rapid onset of action

Answer

To prevent gastric irritation

Answer

To minimize side effects

Question 4

Cardiac glycosides are obtained from which plant source?

Accepted Answer

Strophanthus gratus.

Answer

Rauwolfia serpentina.

Answer

Ricinus communis.

Answer

Atropa belladonna.

Question 5

Which of the following possesses the highest efficacy to increase HDL cholesterol?

Accepted Answer

Nicotinic acid

Answer

Gemfibrosil

Answer

Enoic acid

Answer

Atorvastatin

Question 6

Nitroglycerine can be administered by all of the following routes except?

Accepted Answer

Intramuscular

Answer

Oral

Answer

Sublingual

Answer

Intravenous

Question 7

Which drug is typically administered in cardiogenic shock?

Accepted Answer

Dopamine

Answer

Phenylephrine

Answer

Atropine

Answer

Digoxin

Question 8

Which of the following drugs causes an increase in the effective refractory period of the atrioventricular (AV) node?

Accepted Answer

amiodarone

Answer

bretylium

Answer

procainamide

Answer

quinidine

Question 9

In the treatment of shock, why is Dobutamine preferred over Dopamine?

Accepted Answer

All the above.

Answer

It causes fewer arrhythmias.

Answer

It causes less renal vasodilation.

Answer

It causes less coronary vasoconstriction.

Question 10

Which of the following drugs does not cause bradycardia?

Accepted Answer

Hydralazine

Answer

Propranolol

Answer

Clonidine

Answer

Reserpine

Cardiovascular Drugs — MCQs

Cardiovascular Drugs — MCQs

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