Cardiovascular Drugs — MCQs

Cardiovascular Drugs Indian Medical PG Practice Questions and MCQs

Question 931: What is the major clinical use of nimodipine?

A. Raynaud's phenomenon
B. Hypertension
C. Angina
D. Subarachnoid haemorrhage (Correct Answer)

Explanation: **Explanation:** **Nimodipine** is a second-generation dihydropyridine calcium channel blocker (CCB). While it shares the basic mechanism of other CCBs (blocking L-type calcium channels), it possesses unique pharmacological properties that dictate its clinical use. **1. Why Subarachnoid Haemorrhage (SAH) is correct:** Nimodipine is highly **lipophilic**, allowing it to readily cross the blood-brain barrier. It has a high affinity for cerebral blood vessels. Following a subarachnoid haemorrhage, patients often suffer from delayed **cerebral vasospasm**, which can lead to secondary ischemic neurological deficits. Nimodipine is the drug of choice to prevent and treat this vasospasm, thereby improving neurological outcomes. **2. Why other options are incorrect:** * **Raynaud’s Phenomenon:** While CCBs like Nifedipine or Amlodipine are used to treat Raynaud’s, Nimodipine is not the preferred agent due to its cerebrovascular specificity. * **Hypertension & Angina:** Although Nimodipine can cause vasodilation, it is significantly less potent than Amlodipine or Nifedipine for systemic hypertension or stable angina. Its short half-life and specific action on cerebral vessels make it unsuitable for routine systemic cardiovascular management. **3. High-Yield Clinical Pearls for NEET-PG:** * **Route of Administration:** In SAH, Nimodipine is typically given **orally** (or via nasogastric tube). **Caution:** It should never be injected intravenously from a capsule intended for oral use, as this can cause fatal hypotension. * **Mnemonic:** Remember **"Nimo"** for **"Neuro"** (Cerebral specific). * **Other CCB Specifics:** * **Nicardipine:** Often used for hypertensive emergencies. * **Clevidipine:** Ultra-short-acting IV CCB used for acute BP control.

Question 932: What is the drug of choice for maintenance therapy in PSVT?

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

Explanation: **Explanation:** The management of Paroxysmal Supraventricular Tachycardia (PSVT) is divided into two phases: acute termination and long-term maintenance. **Why Verapamil is the correct answer:** While Adenosine is the drug of choice for the **acute termination** of PSVT, it cannot be used for maintenance due to its extremely short half-life (<10 seconds). For **maintenance therapy** (prophylaxis to prevent recurrences), oral Calcium Channel Blockers (CCBs) like **Verapamil** or Diltiazem are preferred. They act by slowing conduction and prolonging refractoriness in the AV node, effectively preventing the re-entrant circuit that characterizes PSVT. **Analysis of Incorrect Options:** * **Adenosine:** The drug of choice for **acute termination** of PSVT. It causes transient AV block but is unsuitable for maintenance. * **Amiodarone:** A broad-spectrum Class III antiarrhythmic used primarily for ventricular arrhythmias or rhythm control in Atrial Fibrillation. It is not a first-line agent for PSVT maintenance due to its significant side-effect profile (pulmonary fibrosis, thyroid dysfunction). * **Lignocaine:** A Class Ib antiarrhythmic that acts exclusively on ventricular tissues. It has no efficacy in supraventricular arrhythmias like PSVT. **High-Yield Clinical Pearls for NEET-PG:** 1. **Acute Management:** Vagal maneuvers (first-line) $\rightarrow$ IV Adenosine (drug of choice) $\rightarrow$ IV Verapamil/Diltiazem. 2. **Definitive Treatment:** Radiofrequency Ablation (RFA) is the gold standard for permanent cure. 3. **Contraindication:** Avoid Verapamil in PSVT patients with underlying WPW syndrome, as it may paradoxically increase conduction through the accessory pathway, leading to Ventricular Fibrillation.

Question 933: Which drug is known to cause the first-dose phenomenon in elderly patients?

A. Metformin
B. Prazosin (Correct Answer)
C. Acarbose
D. Noradrenaline

Explanation: **Explanation:** **Prazosin** is the correct answer because it is a selective **alpha-1 (α1) adrenergic blocker**. The "first-dose phenomenon" refers to a sudden, severe episode of **orthostatic hypotension** and syncope that occurs within 30 to 90 minutes of the initial dose. This happens because α1-blockade causes rapid peripheral vasodilation and venous pooling. It is particularly pronounced in elderly patients or those on diuretics. To mitigate this, the drug should be started at a low dose ("start low, go slow") and administered at bedtime. **Analysis of Incorrect Options:** * **Metformin (Biguanide):** Primarily causes gastrointestinal side effects (diarrhea, abdominal cramps) and, rarely, lactic acidosis. It does not affect blood pressure acutely. * **Acarbose (Alpha-glucosidase inhibitor):** Acts locally in the gut to delay carbohydrate absorption. Its main side effects are flatulence and bloating; it has no systemic cardiovascular "first-dose" effect. * **Noradrenaline (Catecholamine):** This is a potent vasoconstrictor used to *increase* blood pressure in shock. It would cause hypertension, not the hypotensive collapse associated with the first-dose phenomenon. **NEET-PG High-Yield Pearls:** * **Other drugs causing first-dose effect:** ACE inhibitors (especially in patients with high renin levels or those on diuretics). * **Clinical Management:** Advise patients to take the first dose at **bedtime** to avoid syncopal falls. * **Prazosin uses:** Hypertension, Benign Prostatic Hyperplasia (BPH), and Raynaud's phenomenon. * **Distinction:** Unlike non-selective blockers (Phenoxybenzamine), Prazosin causes **less reflex tachycardia** because it does not block presynaptic α2 receptors.

Question 934: What is the mechanism of action of quinidine on the heart?

A. Calcium channel blocker
B. Potassium channel blocker (Correct Answer)
C. Sodium channel opener
D. Chloride channel opener

Explanation: Quinidine is a **Class IA antiarrhythmic** drug. According to the Vaughan Williams classification, Class I drugs primarily act by blocking voltage-gated sodium channels [1, 2]. However, Class IA agents (Quinidine, Procainamide, Disopyramide) are unique because they possess significant **potassium channel blocking** activity (specifically the $I_{Kr}$ current) [1, 2]. By blocking potassium channels during Phase 3 of the cardiac action potential, quinidine prolongs the action potential duration (APD) and the effective refractory period (ERP) [1]. This is reflected on an ECG as a **prolonged QT interval** [1]. **Analysis of Options:** * **Option B (Correct):** Quinidine blocks potassium channels, leading to delayed repolarization. This is its distinguishing feature compared to Class IB drugs. * **Option A:** Calcium channel blockers (Class IV) include drugs like Verapamil and Diltiazem. While quinidine has some alpha-blocking activity, it is not a primary calcium channel blocker. * **Option C:** Quinidine is a sodium channel **blocker** (decreasing the slope of Phase 0), not an opener. * **Option D:** Chloride channels are not the primary target for standard antiarrhythmic therapy in the Vaughan Williams classification. **High-Yield Clinical Pearls for NEET-PG:** * **Cinchonism:** A classic side effect profile including tinnitus, headache, and dizziness. * **Torsades de Pointes:** Due to QT prolongation (potassium channel blockade), quinidine carries a high risk of polymorphic ventricular tachycardia. * **Vagolytic Effect:** Quinidine has antimuscarinic properties that can paradoxically increase AV conduction; it is often co-administered with digoxin or beta-blockers to prevent rapid ventricular rates in atrial flutter/fibrillation. * **Drug Interaction:** It increases plasma levels of **Digoxin** by displacing it from tissue binding sites and reducing renal clearance.

Question 935: Statins act on which enzyme?

A. Acyl CoA synthetase
B. Acyl CoA reductase
C. HMG CoA synthetase
D. HMG CoA reductase (Correct Answer)

Explanation: **Explanation:** **Correct Answer: D. HMG CoA reductase** Statins (HMG-CoA reductase inhibitors) are the first-line drugs for treating hypercholesterolemia. They act by competitively inhibiting the enzyme **3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase**. This enzyme is the **rate-limiting step** in the mevalonate pathway of endogenous cholesterol synthesis. By inhibiting this enzyme, statins decrease intracellular cholesterol levels, which triggers an up-regulation of LDL receptors on hepatocytes, leading to increased clearance of LDL-C from the blood. **Analysis of Incorrect Options:** * **A & B (Acyl CoA synthetase/reductase):** These enzymes are involved in fatty acid metabolism and the activation of long-chain fatty acids, not the primary rate-limiting step of cholesterol synthesis. * **C (HMG CoA synthetase):** This enzyme catalyzes the formation of HMG-CoA from Acetyl-CoA and Acetoacetyl-CoA. While it is part of the pathway, it is not the rate-limiting step and is not the target of statin therapy. **High-Yield Clinical Pearls for NEET-PG:** * **Pleiotropic Effects:** Statins have benefits beyond lipid-lowering, including plaque stabilization, anti-inflammatory effects, and improved endothelial function. * **Timing of Dose:** Since cholesterol synthesis peaks at night, statins with short half-lives (e.g., Lovastatin, Simvastatin) should be taken at **bedtime**. Long-acting statins (Atorvastatin, Rosuvastatin) can be taken any time. * **Adverse Effects:** The most important side effects are **myopathy/rhabdomyolysis** (monitored via CPK levels) and hepatotoxicity (monitored via LFTs). * **Contraindication:** Statins are strictly **contraindicated in pregnancy** (Teratogenic).

Question 936: ACE inhibitors are contraindicated in which of the following conditions?

A. Bilateral renal artery stenosis (Correct Answer)
B. Chronic kidney disease
C. Post myocardial infarction
D. Diabetes mellitus

Explanation: **Explanation:** **Why Bilateral Renal Artery Stenosis (RAS) is the Correct Answer:** In patients with bilateral RAS, renal perfusion pressure is significantly reduced. To maintain an adequate Glomerular Filtration Rate (GFR), the body relies on **Angiotensin II-mediated vasoconstriction of the efferent arteriole**. ACE inhibitors block the production of Angiotensin II, leading to efferent arteriolar vasodilation. This causes a precipitous drop in intraglomerular pressure, resulting in **acute renal failure**. Therefore, ACE inhibitors are strictly contraindicated in bilateral RAS (or unilateral RAS in a solitary functioning kidney). **Analysis of Incorrect Options:** * **B. Chronic Kidney Disease (CKD):** ACE inhibitors are actually **renoprotective** in early-to-moderate CKD. They reduce intraglomerular pressure and proteinuria, slowing the progression of diabetic and non-diabetic nephropathy. However, they must be used cautiously if serum creatinine is >3 mg/dL. * **C. Post Myocardial Infarction:** ACE inhibitors are a cornerstone of post-MI therapy. They prevent **ventricular remodeling**, reduce mortality, and are indicated in all patients post-MI, especially those with reduced ejection fraction. * **D. Diabetes Mellitus:** ACE inhibitors are the **first-line antihypertensives** for diabetic patients because they delay the onset and progression of diabetic nephropathy. **High-Yield Clinical Pearls for NEET-PG:** * **Teratogenicity:** ACE inhibitors are contraindicated in **pregnancy** (cause fetal renal anomalies and oligohydramnios). * **Side Effects:** Remember the mnemonic **CAPTOPRIL** (Cough, Angioedema, Proteinuria, Taste changes, Orthostatic hypotension, Pregnancy contraindication, Renal artery stenosis, Increased potassium/Hyperkalemia, Leukopenia). * **Dry Cough:** Caused by the accumulation of **Bradykinin** and Substance P in the lungs. * **Monitoring:** Always check serum creatinine and potassium levels within 1–2 weeks of starting an ACE inhibitor.

Question 937: What does chronotropic mean?

A. Drugs affecting the contractility of the heart
B. Drugs affecting heart rate (Correct Answer)
C. Drugs affecting the myocardial blood flow
D. Drugs affecting diastolic relaxation

Explanation: **Explanation:** The term **Chronotropic** is derived from the Greek word *chronos* (meaning time). In cardiovascular pharmacology, it refers to drugs or factors that influence the **heart rate** by affecting the rate of impulse formation in the sinoatrial (SA) node. * **Positive chronotropes** (e.g., Adrenaline, Atropine) increase the heart rate. * **Negative chronotropes** (e.g., Beta-blockers, Digoxin, Verapamil) decrease the heart rate. **Analysis of Incorrect Options:** * **Option A (Contractility):** This is termed **Inotropic**. Positive inotropes (e.g., Digoxin, Dobutamine) increase the force of contraction, while negative inotropes (e.g., Beta-blockers) decrease it. * **Option C (Myocardial blood flow):** This refers to coronary perfusion. Drugs affecting this are typically coronary vasodilators (e.g., Nitroglycerin). * **Option D (Diastolic relaxation):** This is termed **Lusitropic**. Positive lusitropy (e.g., Catecholamines via phospholamban phosphorylation) improves the rate of myocardial relaxation. **High-Yield NEET-PG Pearls:** 1. **Dromotropic:** Refers to the velocity of conduction (usually through the AV node). 2. **Bathmotropic:** Refers to the degree of excitability of the cardiac muscle. 3. **Digoxin Unique Profile:** It is a **Positive Inotrope** (increases force) but a **Negative Chronotrope** (decreases rate) and **Negative Dromotrope** (decreases AV conduction). This makes it ideal for Heart Failure with Atrial Fibrillation. 4. **Ivabradine:** A pure negative chronotropic agent that acts by inhibiting the *If* (funny) current in the SA node without affecting contractility.

Question 938: Which of the following does not result in the release of nitric oxide?

A. Fenoldopam (Correct Answer)
B. Hydralazine
C. Nitroprusside
D. Nitroglycerin

Explanation: ### Explanation **Correct Option: A. Fenoldopam** **Mechanism of Action:** Fenoldopam is a selective **Dopamine-1 (D1) receptor agonist**. It causes vasodilation by stimulating D1 receptors, which increases intracellular **cAMP** (cyclic Adenosine Monophosphate) levels, leading to the relaxation of vascular smooth muscle. Unlike the other drugs listed, its mechanism is entirely independent of the Nitric Oxide (NO)-cGMP pathway. It is primarily used in the management of hypertensive emergencies, especially when renal perfusion needs to be maintained. **Analysis of Incorrect Options:** * **B. Hydralazine:** This is a direct-acting vasodilator. While its exact mechanism is complex, it is known to stimulate the release of **Nitric Oxide** from the vascular endothelium, leading to cGMP-mediated vasodilation of arterioles [1]. * **C. Nitroprusside:** This is a parenteral vasodilator that acts as an **NO donor** [2]. It is non-enzymatically converted to Nitric Oxide in the blood, which activates guanylyl cyclase to increase cGMP, dilating both arterioles and venules. * **D. Nitroglycerin:** This organic nitrate undergoes **enzymatic bioactivation** (via mitochondrial aldehyde dehydrogenase) to release Nitric Oxide, primarily causing venodilation and reducing cardiac preload [2, 3]. **High-Yield Clinical Pearls for NEET-PG:** * **Fenoldopam Unique Property:** It is the only intravenous antihypertensive that improves **renal perfusion** (natriuresis and diuresis) while lowering blood pressure, making it ideal for hypertensive emergencies with renal compromise. * **Nitroprusside Toxicity:** Prolonged infusion can lead to **Cyanide and Thiocyanate toxicity**. The antidote is Sodium Thiosulfate or Hydroxocobalamin. * **Nitrate Tolerance:** Continuous use of Nitroglycerin leads to "tachyphylaxis" due to the depletion of free sulfhydryl groups; a "nitrate-free interval" (8–12 hours) is required to restore sensitivity.

Question 939: Which is the best inotropic drug for use in right heart failure?

A. Dobutamine
B. Digoxin
C. Dopamine
D. Milrinone (Correct Answer)

Explanation: **Explanation:** **Milrinone** is a Phosphodiesterase-3 (PDE3) inhibitor. It increases intracellular cAMP in the myocardium, leading to increased contractility (inotropy). Crucially, it also increases cAMP in vascular smooth muscle, causing systemic and **pulmonary vasodilation** (lusitropy and vasodilation). In right heart failure (RHF), the right ventricle (RV) is often struggling against high pulmonary vascular resistance (PVR). Milrinone is the "best" choice because it provides "Inodilatation"—improving RV contractility while simultaneously decreasing the afterload on the RV by dilating the pulmonary artery. **Analysis of Incorrect Options:** * **Dobutamine:** A $\beta_1$ agonist that increases cardiac output. While it is a potent inotrope, it has less pronounced effects on reducing pulmonary vascular resistance compared to Milrinone and can increase myocardial oxygen demand significantly. * **Digoxin:** A weak inotrope that inhibits Na+/K+ ATPase. It is primarily used for rate control in atrial fibrillation or symptomatic relief in chronic HFrEF, but it is not the drug of choice for acute right heart failure management. * **Dopamine:** At higher doses, it has $\alpha_1$ agonistic effects which can increase systemic and pulmonary vascular resistance, potentially worsening the strain on a failing right ventricle. **High-Yield Clinical Pearls for NEET-PG:** * **"Inodilators":** Milrinone and Levosimendan are categorized as inodilators (Inotrope + Vasodilator). * **Renal Caution:** Milrinone is renally cleared; dosage adjustment is required in renal failure. * **Side Effect:** The most common side effect of Milrinone is hypotension (due to vasodilation) and arrhythmias. * **Mechanism:** PDE3 inhibition $\rightarrow$ $\uparrow$ cAMP $\rightarrow$ $\uparrow$ Calcium influx in heart (contraction) and $\uparrow$ Calcium uptake in smooth muscle (relaxation).

Question 940: Nestritide is a -

A. Brain Natriuretic peptide analogue (Correct Answer)
B. Endothelin receptor antagonist
C. Glycoprotein IIb/IIIa antagonist
D. Interferon-alpha antagonist

Explanation: **Explanation:** **Nesiritide** is a recombinant form of human **B-type Natriuretic Peptide (BNP)**. It works by binding to the particulate guanylyl cyclase receptor (NPR-A) on vascular smooth muscle and endothelial cells, leading to increased intracellular **cGMP**. This results in potent venous and arterial vasodilation (reducing both preload and afterload) and promotes natriuresis (sodium excretion) and diuresis. It is primarily used in the management of acutely decompensated heart failure with dyspnea at rest. **Analysis of Incorrect Options:** * **Option B (Endothelin receptor antagonist):** These include drugs like **Bosentan** and Macitentan, which are used in the treatment of Pulmonary Arterial Hypertension (PAH). * **Option C (Glycoprotein IIb/IIIa antagonist):** These are antiplatelet agents like **Abciximab**, Eptifibatide, and Tirofiban, used in Acute Coronary Syndromes and percutaneous coronary interventions. * **Option D (Interferon-alpha antagonist):** There is no standard drug class by this name; Interferon-alpha is itself used as an antiviral or antineoplastic agent (e.g., in Hepatitis B/C or CML). **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Increases cGMP (similar to Nitroglycerin and Sildenafil). * **Hemodynamic effect:** It is a "balanced" vasodilator (decreases PCWP and SVR). * **Side Effect:** The most common side effect is **hypotension**. It may also be associated with a risk of renal dysfunction. * **Sacubitril connection:** Sacubitril (a Neprilysin inhibitor) prevents the breakdown of endogenous BNP, working on the same pathway as Nesiritide.

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

Practice Questions

Thrombolytic Agents

Practice Questions

Drugs Used in Pulmonary Hypertension

Practice Questions

Drugs Used in Shock

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Cardiovascular Effects of Non-Cardiovascular Drugs

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