Cardiovascular Drugs — MCQs

Cardiovascular Drugs Indian Medical PG Practice Questions and MCQs

Question 821: Which of the following is NOT an adrenergic neuron blocking drug?

A. Reserpine
B. Guanethidine (Correct Answer)
C. Bretylium
D. Minoxidil

Explanation: **Explanation:** Adrenergic neuron blocking drugs act by interfering with the release or storage of norepinephrine (NE) from the sympathetic nerve terminals. They do not block adrenergic receptors directly but rather deplete the neurotransmitter or prevent its exocytosis. **Why Minoxidil is the Correct Answer (The Exception):** **Minoxidil (Option D)** is a **direct-acting vasodilator**. It works by opening ATP-sensitive potassium channels ($K_{ATP}$) in vascular smooth muscle, leading to hyperpolarization and relaxation of arterioles. It has no direct inhibitory effect on the sympathetic nerve terminal or the release of norepinephrine. **Analysis of Other Options:** * **Reserpine (Option A):** An adrenergic neuron blocker that inhibits the **VMAT-2** (Vesicular Monoamine Transporter), preventing the storage of NE in vesicles, leading to its depletion. * **Guanethidine (Option B):** A classic adrenergic neuron blocker that is transported into the nerve terminal via the NET (Norepinephrine Transporter). It displaces NE from vesicles and prevents its release (stabilizes the membrane). * **Bretylium (Option C):** Primarily used as a Class III antiarrhythmic, it also acts as an adrenergic neuron blocker by inhibiting the release of NE in response to a nerve impulse. **High-Yield Clinical Pearls for NEET-PG:** * **Reserpine Side Effect:** Known for causing severe **depression** and suicidal tendencies due to depletion of serotonin and dopamine in the CNS. * **Minoxidil Side Effects:** Can cause **hypertrichosis** (excessive hair growth) and reflex tachycardia (often co-prescribed with beta-blockers). * **Guanethidine Interaction:** Its uptake is blocked by **Tricyclic Antidepressants (TCAs)**, which can reverse its antihypertensive effects.

Question 822: Which of the following acts by inhibiting HMG CoA reductase?

A. Ezetimibe
B. Gemfibrozil
C. Clofibrate
D. Lovastatin (Correct Answer)

Explanation: **Explanation:** **Correct Option: D. Lovastatin** Lovastatin belongs to the **Statins** class of drugs, which are the first-line agents for treating hypercholesterolemia. The underlying mechanism involves the competitive inhibition of **HMG-CoA reductase**, the rate-limiting enzyme in the melevonate pathway of cholesterol synthesis. By inhibiting this enzyme, statins decrease intracellular cholesterol levels in hepatocytes, leading to the compensatory up-regulation of **LDL receptors** on the cell surface. This results in increased clearance of LDL-C from the plasma. **Incorrect Options:** * **A. Ezetimibe:** This drug acts by inhibiting the **NPC1L1 transporter** in the brush border of the small intestine, thereby blocking the absorption of dietary and biliary cholesterol. * **B & C. Gemfibrozil and Clofibrate:** These are **Fibrates**. Their primary mechanism is the activation of **PPAR-α** (Peroxisome Proliferator-Activated Receptor-alpha), which increases the expression of lipoprotein lipase (LPL), primarily reducing triglyceride levels. **High-Yield Clinical Pearls for NEET-PG:** * **Pleiotropic effects:** Statins also provide "non-lipid" benefits such as plaque stabilization, anti-inflammatory effects, and improved endothelial function. * **Side Effects:** The most significant side effects are **myopathy/rhabdomyolysis** (monitored via CPK levels) and hepatotoxicity (monitored via LFTs). * **Contraindication:** Statins are strictly **contraindicated in pregnancy** (Teratogenic). * **Timing:** Lovastatin and Simvastatin are usually taken at night because hepatic cholesterol synthesis peaks between midnight and 2:00 AM.

Question 823: What is the drug of choice for acute left ventricular failure?

A. Rapid digitalization
B. Intravenous Aminophylline
C. Intravenous Morphine
D. Intravenous Furosemide (Correct Answer)

Explanation: **Explanation:** Acute Left Ventricular Failure (LVF) presents as acute pulmonary edema due to fluid overload and increased pulmonary capillary wedge pressure. **Why Intravenous Furosemide is the Drug of Choice:** Furosemide is a high-ceiling loop diuretic that acts via two distinct mechanisms in acute LVF: 1. **Immediate Vasodilation:** When given IV, it causes rapid venodilation (mediated by prostaglandins) within 5–15 minutes. This increases venous capacitance, decreasing venous return (preload) and relieving pulmonary congestion even before the diuretic effect begins. 2. **Diuresis:** It inhibits the Na⁺-K⁺-2Cl⁻ cotransporter in the thick ascending limb of the Loop of Henle, leading to significant fluid excretion, which reduces circulating blood volume. **Analysis of Incorrect Options:** * **A. Rapid Digitalization:** Digoxin has a slow onset of action and narrow therapeutic index. It is no longer used for acute stabilization as it does not address the immediate need for preload reduction. * **B. Intravenous Aminophylline:** Once used for "cardiac asthma" to relieve bronchospasm, it is now avoided due to its narrow therapeutic window and risk of precipitating fatal arrhythmias in an already ischemic or stressed myocardium. * **C. Intravenous Morphine:** While morphine helps by causing venodilation and reducing patient anxiety (dyspnea), it is considered an **adjunct** therapy. Recent guidelines (like ESC) have downgraded its routine use due to risks of respiratory depression. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for Acute LVF Management:** **LMNOP** (**L**asix/Furosemide, **M**orphine, **N**itrates, **O**xygen, **P**ositioning/CPAP). * **DOC for Chronic Heart Failure:** ACE Inhibitors (shown to reduce mortality). * **DOC for Acute Pulmonary Edema:** IV Furosemide. * **Note:** If the patient is in cardiogenic shock (low BP), diuretics should be used with extreme caution; inotropes like Dobutamine become priority.

Question 824: What is the drug of choice for maintenance in paroxysmal supraventricular tachycardia (PSVT)?

A. Amiodarone
B. Lignocaine
C. Verapamil
D. Adenosine (Correct Answer)

Explanation: **Explanation:** **Adenosine** is the drug of choice for the **acute termination** of Paroxysmal Supraventricular Tachycardia (PSVT). Its mechanism involves the activation of $A_1$ receptors on the AV node, which increases potassium efflux and inhibits calcium influx. This leads to profound hyperpolarization and a transient "chemical cardioversion" by slowing conduction through the AV node, effectively breaking the re-entrant circuit. **Analysis of Options:** * **Adenosine (Correct):** It has an ultra-short half-life (<10 seconds), making it ideal for rapid termination of PSVT with minimal systemic side effects. * **Amiodarone:** A Class III antiarrhythmic used primarily for ventricular arrhythmias and atrial fibrillation. It is not the first-line choice for PSVT due to its slow onset and extensive side-effect profile. * **Lignocaine:** A Class IB sodium channel blocker. It is effective only for **ventricular arrhythmias** (post-MI) and has no efficacy in supraventricular arrhythmias like PSVT. * **Verapamil:** A Calcium Channel Blocker (Class IV). While it can be used for PSVT, it is considered a second-line agent compared to Adenosine because it causes more prolonged hypotension and has a slower onset of action. **High-Yield Clinical Pearls for NEET-PG:** * **Administration:** Adenosine must be given as a **rapid IV bolus** (usually 6mg followed by 12mg) through a large-bore peripheral vein, followed by a saline flush, due to its rapid metabolism by erythrocytes and vascular endothelial cells. * **Contraindications:** Avoid in patients with **Asthma** (may cause bronchospasm) and **High-degree AV block**. * **Drug Interactions:** The effects of Adenosine are **potentiated by Dipyridamole** and **antagonized by Theophylline/Caffeine** (adenosine receptor blockers). * **Side Effects:** Patients often experience a transient sense of "impending doom," chest pain, or flushing.

Question 825: All of the following drugs belong to Class 1 antiarrhythmic drugs except?

A. Quinidine
B. Procainamide
C. Flecainide
D. Propanolol (Correct Answer)

Explanation: **Explanation:** The classification of antiarrhythmic drugs is based on the **Vaughan Williams Classification**, which categorizes drugs according to their primary mechanism of action on the cardiac action potential. **Why Propranolol is the correct answer:** Propranolol is a non-selective beta-adrenergic blocker. According to the Vaughan Williams classification, beta-blockers belong to **Class II**. They work by inhibiting sympathetic stimulation, decreasing the slope of Phase 4 depolarization in pacemaker cells (SA and AV nodes), thereby reducing heart rate and conduction velocity. **Analysis of Incorrect Options (Class I Drugs):** Class I drugs are primarily **Sodium (Na+) channel blockers** that decrease the rate of Phase 0 depolarization. They are subdivided into three groups: * **Option A (Quinidine) & Option B (Procainamide):** These belong to **Class IA**. They moderately block Na+ channels and also block K+ channels, which prolongs the action potential duration (APD) and the QT interval. * **Option C (Flecainide):** This belongs to **Class IC**. It is a potent Na+ channel blocker with minimal effect on APD. It significantly slows conduction and is used for supraventricular arrhythmias in patients without structural heart disease. **High-Yield NEET-PG Pearls:** * **Class IB (e.g., Lidocaine, Mexiletine):** These shorten the APD and are specifically effective for ventricular arrhythmias, especially post-Myocardial Infarction. * **Class III (e.g., Amiodarone, Sotalol):** These are Potassium (K+) channel blockers that prolong Phase 3 repolarization. * **Class IV (e.g., Verapamil, Diltiazem):** These are Calcium (Ca2+) channel blockers. * **Mnemonic for Class I:** "**D**ouble **Q**uarter **P**ounder, **L**ettuce **M**ayo **T**omato, **F**ries **P**lease" (**IA:** **D**isopyramide, **Q**uinidine, **P**rocainamide; **IB:** **L**idocaine, **M**exiletine, **T**ocainide; **IC:** **F**lecainide, **P**ropafenone).

Question 826: Which of the following antihypertensive drugs is contraindicated in pregnancy?

A. Amlodipine
B. Labetalol
C. Enalapril (Correct Answer)
D. Hydralazine

Explanation: **Explanation:** **Enalapril** is an ACE inhibitor (ACEI) and is strictly **contraindicated** in pregnancy (Pregnancy Category D/X). ACEIs and Angiotensin Receptor Blockers (ARBs) interfere with the fetal renin-angiotensin system, which is crucial for fetal renal development. Exposure, particularly in the 2nd and 3rd trimesters, leads to **fetal renal dysgenesis**, oligohydramnios (due to decreased fetal urine output), pulmonary hypoplasia, intrauterine growth restriction (IUGR), and cranial ossification defects. **Analysis of Incorrect Options:** * **Labetalol (Option B):** A combined alpha and beta-blocker, it is considered the **first-line drug** for managing chronic hypertension and gestational hypertension in pregnancy due to its safety profile. * **Hydralazine (Option D):** A direct vasodilator used primarily in the acute management of **severe pre-eclampsia** or hypertensive emergencies in pregnancy. * **Amlodipine (Option A):** A Calcium Channel Blocker (CCB). While Nifedipine is more commonly used and studied in pregnancy, Amlodipine is generally considered safe if required. **High-Yield Clinical Pearls for NEET-PG:** * **Safe Antihypertensives in Pregnancy:** "Better Mother Care During Hypertensive" (Mnemonic: **B**eta-blockers [Labetalol], **M**ethyldopa, **C**alcium channel blockers [Nifedipine], **D**irect vasodilators [Hydralazine]). * **Drug of Choice:** **Labetalol** is the current DOC; **Methyldopa** was historically the DOC and remains safe. * **Teratogenic Risk:** ACEIs/ARBs are associated with "ACEI Fetopathy." Statins and Diuretics are also generally avoided in pregnancy.

Question 827: Which of the following medications would be prescribed most frequently to patients suffering from chronic atrial fibrillation?

A. Lidocaine
B. Bretylium
C. Warfarin (Correct Answer)
D. Adenosine

Explanation: **Explanation:** In **chronic atrial fibrillation (AF)**, the primary clinical concern is not just rate or rhythm control, but the prevention of **thromboembolism**. Due to the ineffective contraction of the atria, blood stasis occurs (particularly in the left atrial appendage), leading to the formation of mural thrombi. These thrombi can embolize, causing ischemic strokes. Therefore, long-term anticoagulation with **Warfarin** (a Vitamin K antagonist) or DOACs (Direct Oral Anticoagulants) is the mainstay of management to reduce stroke risk. **Analysis of Incorrect Options:** * **A. Lidocaine:** This is a Class IB antiarrhythmic used primarily for acute **ventricular arrhythmias** (e.g., post-MI). It has no role in atrial arrhythmias because it binds preferentially to sodium channels in ventricular tissues. * **B. Bretylium:** A Class III antiarrhythmic previously used for refractory ventricular fibrillation. It is rarely used today due to its side effect profile (severe hypotension) and is not indicated for chronic AF. * **D. Adenosine:** This drug is the treatment of choice for terminating **Paroxysmal Supraventricular Tachycardia (PSVT)**. It works by transiently blocking the AV node but has an extremely short half-life (seconds) and is not used for chronic management of AF. **NEET-PG High-Yield Pearls:** * **CHADS₂ / CHA₂DS₂-VASc Score:** Used to determine the necessity of anticoagulation in AF patients. * **Target INR:** For a patient on Warfarin for AF, the target INR is typically **2.0–3.0**. * **Drug of Choice for Rate Control:** Beta-blockers or Calcium Channel Blockers (Verapamil/Diltiazem). * **Drug of Choice for Rhythm Control:** Amiodarone or Flecainide (if no structural heart disease).

Question 828: The antianginal effect of propranolol may be attributed to which of the following?

A. Block of exercise-induced tachycardia (Correct Answer)
B. Dilation of constricted coronary vessels
C. Increased cardiac force
D. Increased resting heart rate

Explanation: **Explanation:** The primary goal in treating stable angina is to restore the balance between myocardial oxygen supply and demand. Propranolol, a non-selective beta-blocker, achieves this primarily by **reducing myocardial oxygen demand**. **1. Why Option A is Correct:** The most significant determinant of myocardial oxygen consumption during exertion is the heart rate. Propranolol blocks $\beta_1$ receptors in the SA node, effectively **blocking exercise-induced tachycardia**. By preventing the heart rate from rising during physical activity, it reduces the workload of the heart. Additionally, a slower heart rate increases the duration of **diastole**, which is the period when coronary perfusion occurs, thereby marginally improving oxygen supply. **2. Why the Other Options are Incorrect:** * **Option B:** Propranolol causes **vasoconstriction**, not dilation, of coronary vessels. By blocking $\beta_2$ receptors (which mediate vasodilation), it leaves $\alpha$-mediated vasoconstriction unopposed. This is why beta-blockers are contraindicated in Vasospastic (Prinzmetal) angina. * **Option C:** Propranolol has a **negative inotropic effect** (decreases cardiac force). While this helps reduce oxygen demand, the option states "increased force," which is physiologically opposite to the drug's action. * **Option D:** Propranolol **decreases** resting heart rate (negative chronotropy); it does not increase it. **Clinical Pearls for NEET-PG:** * **DOC for Stable Angina:** Beta-blockers are the first-line maintenance therapy. * **Contraindication:** Never use Propranolol in **Prinzmetal Angina** (use Calcium Channel Blockers instead) or in patients with **Asthma/COPD** (due to $\beta_2$ blockade causing bronchospasm). * **Withdrawal:** Abrupt cessation can lead to "Rebound Hypertension" or MI due to up-regulation of beta-receptors.

Question 829: Abciximab is

A. Antithrombin III inhibitor
B. Gp IIb/IIIa antibody (Correct Answer)
C. Alanine analogue
D. P2Y12 purine receptor antagonist

Explanation: **Explanation:** **Abciximab** is a potent antiplatelet agent classified as a **Glycoprotein (Gp) IIb/IIIa receptor antagonist**. It is a chimeric monoclonal antibody fragment (Fab) that binds irreversibly to the Gp IIb/IIIa receptor on the platelet surface. This receptor is the "final common pathway" for platelet aggregation; by blocking it, Abciximab prevents the binding of fibrinogen and von Willebrand factor, thereby inhibiting platelet-to-platelet cross-linking regardless of the initial stimulus (ADP, Thrombin, or Collagen). **Analysis of Incorrect Options:** * **Option A (Antithrombin III inhibitor):** This is incorrect. Drugs like **Heparin** actually *activate* Antithrombin III to inhibit clotting factors (IIa and Xa). There is no standard therapeutic class called "Antithrombin III inhibitors." * **Option C (Alanine analogue):** This is a distractor. Abciximab is a protein (monoclonal antibody), not a simple amino acid analogue. * **Option D (P2Y12 receptor antagonist):** This describes drugs like **Clopidogrel, Prasugrel, and Ticagrelor**, which inhibit the ADP-mediated pathway of platelet activation, rather than the final aggregation receptor. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Irreversible blockade of Gp IIb/IIIa. * **Other Gp IIb/IIIa inhibitors:** **Eptifibatide** (cyclic peptide) and **Tirofiban** (non-peptide). Unlike Abciximab, these are reversible. * **Clinical Use:** Primarily used during **Percutaneous Coronary Intervention (PCI)** to prevent ischemic complications and in unstable angina. * **Side Effect:** The most significant risk is bleeding and **thrombocytopenia**. * **Monitoring:** Platelet counts should be monitored within 24 hours of administration.

Question 830: Which of the following drugs has the maximum half-life?

A. Adenosine
B. Amiodarone (Correct Answer)
C. Esmolol
D. Lidocaine

Explanation: **Explanation:** The correct answer is **Amiodarone**. The concept being tested here is the pharmacokinetic profile of antiarrhythmic drugs, specifically their elimination half-lives. **1. Why Amiodarone is correct:** Amiodarone (a Class III antiarrhythmic) is highly **lipophilic** and sequesters extensively into tissues like adipose, liver, and lungs. It has a massive volume of distribution ($V_d$). Consequently, it has an exceptionally long elimination half-life, typically ranging from **25 to 60 days** (average ~58 days). This necessitates a "loading dose" to achieve steady-state plasma concentrations quickly. **2. Why the other options are incorrect:** * **Adenosine:** Has the shortest half-life in clinical medicine, lasting **less than 10 seconds** due to rapid uptake by erythrocytes and endothelial cells. It is administered as a rapid IV bolus for PSVT. * **Esmolol:** An ultra-short-acting Class II beta-blocker. It is metabolized by **red blood cell esterases**, giving it a half-life of approximately **9 minutes**. It is ideal for perioperative arrhythmia control. * **Lidocaine:** A Class Ib antiarrhythmic with a half-life of about **1.5 to 2 hours**. It undergoes extensive first-pass metabolism in the liver. **High-Yield Clinical Pearls for NEET-PG:** * **Amiodarone Toxicity:** Due to its long half-life, side effects (pulmonary fibrosis, thyroid dysfunction, corneal microdeposits, and blue-gray skin discoloration) can persist long after the drug is discontinued. * **Iodine Content:** Amiodarone is structurally related to thyroxine and contains roughly 37% iodine by weight. * **Drug of Choice:** Amiodarone is the preferred drug for rhythm control in patients with structural heart disease or heart failure.

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

Practice Questions

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