Cardiovascular Drugs — MCQs

Cardiovascular Drugs Indian Medical PG Practice Questions and MCQs

Question 741: What effect does Dobutamine have?

A. Increased cardiac output (Correct Answer)
B. Marked increase in heart rate
C. Increased total peripheral resistance
D. Marked increase in blood pressure

Explanation: **Explanation:** Dobutamine is a synthetic catecholamine that acts primarily as a **selective $\beta_1$-adrenergic agonist**. Its primary clinical effect is a significant increase in myocardial contractility (**positive inotropy**) with a relatively lesser effect on heart rate (**positive chronotropy**). By increasing the force of contraction, it effectively increases the stroke volume, leading to an **increased cardiac output**. This makes it the drug of choice for cardiogenic shock and severe heart failure. **Analysis of Options:** * **A (Correct):** The potent $\beta_1$ stimulation increases stroke volume and cardiac output, which is the hallmark hemodynamic effect of Dobutamine. * **B (Incorrect):** While Dobutamine can increase heart rate, it does so much less "markedly" than drugs like Isoprenaline. At therapeutic doses, the increase in inotropy is more prominent than chronotropy. * **C (Incorrect):** Dobutamine has weak $\beta_2$ agonist activity which may cause mild vasodilation, and very weak $\alpha_1$ activity. The net effect is usually a slight **decrease** or no change in total peripheral resistance (TPR). * **D (Incorrect):** Because Dobutamine often causes mild peripheral vasodilation ($\beta_2$ effect) while increasing cardiac output, the mean blood pressure usually remains stable or increases only slightly. It does not cause a "marked" increase in BP compared to vasopressors like Noradrenaline. **High-Yield Clinical Pearls for NEET-PG:** * **Dobutamine Stress Echocardiography (DSE):** Used to diagnose ischemic heart disease in patients unable to perform exercise. * **Half-life:** Very short (~2 minutes), requiring continuous IV infusion. * **Tolerance:** Pharmacological tolerance (tachyphylaxis) can develop with prolonged use (>72 hours) due to down-regulation of $\beta$-receptors.

Question 742: Nitroglycerine is used in Angina pectoris. What is its primary mechanism of action?

A. Arteriolar dilator
B. Post-capillary venodilator (Correct Answer)
C. Increase in myocardial oxygen demand
D. Decrease in myocardial workload

Explanation: **Explanation:** Nitroglycerine (NTG) is a nitrate that acts as a prodrug, releasing **Nitric Oxide (NO)**. NO activates guanylyl cyclase, increasing cGMP levels, which leads to dephosphorylation of myosin light chains and smooth muscle relaxation. **Why Option B is Correct:** At therapeutic doses, Nitroglycerine acts **predominantly on the venous system** (specifically post-capillary venules). By causing **venodilation**, it increases venous capacitance, leading to peripheral pooling of blood. This results in **decreased venous return (Preload)** to the heart. A reduction in preload decreases left ventricular end-diastolic pressure (LVEDP) and wall tension, which significantly lowers myocardial oxygen demand—the primary mechanism for relieving angina. **Why Other Options are Incorrect:** * **Option A:** While nitrates can cause arteriolar dilation at high doses, their primary and most significant effect at clinical doses is venodilation. Pure arteriolar dilators (like Hydralazine) are not first-line for angina. * **Option C:** Nitroglycerine **decreases** myocardial oxygen demand. Increasing demand would worsen anginal pain. * **Option D:** While NTG does decrease workload, this is a *result* of its primary action. In the context of "primary mechanism of action" regarding its vascular effect, **post-capillary venodilation** is the specific pharmacological answer required. **High-Yield NEET-PG Pearls:** * **Drug of Choice:** Sublingual NTG is the DOC for acute anginal attacks. * **Nitrate Tolerance:** Continuous exposure leads to "tachyphylaxis" (depletion of free sulfhydryl groups). A **10–12 hour nitrate-free interval** (usually at night) is essential to prevent this. * **Monday Disease:** Workers in dynamite factories experience headache and dizziness on Mondays due to loss of tolerance developed over the weekend. * **Contraindication:** Never co-administer with **Sildenafil** (PDE-5 inhibitors) as it can cause life-threatening hypotension.

Question 743: Which of the following drugs is a third-generation beta-blocker?

A. Propranolol
B. Timolol
C. Nadolol
D. Nebivolol (Correct Answer)

Explanation: **Explanation:** Beta-blockers are classified into three generations based on their receptor selectivity and additional pharmacological properties (vasodilatory activity). **1. Why Nebivolol is Correct:** **Nebivolol** is a **third-generation beta-blocker**. These drugs are unique because they possess **vasodilatory properties** in addition to beta-blockade. Nebivolol is the most cardioselective $\beta_1$ blocker currently available and induces vasodilation by increasing the production of **Nitric Oxide (NO)** from the vascular endothelium. This dual mechanism results in improved peripheral blood flow and a better metabolic profile compared to older generations. **2. Analysis of Incorrect Options:** * **A, B, and C (Propranolol, Timolol, Nadolol):** These are all **first-generation beta-blockers**. They are **non-selective**, meaning they block both $\beta_1$ (heart) and $\beta_2$ (bronchi, blood vessels) receptors. They lack vasodilatory activity and are contraindicated in patients with asthma or COPD due to the risk of bronchospasm. **3. High-Yield Clinical Pearls for NEET-PG:** * **Classification Summary:** * **1st Gen (Non-selective):** Propranolol (prototype), Sotalol, Timolol, Nadolol. * **2nd Gen (Cardioselective $\beta_1$):** Metoprolol, Atenolol, Esmolol (shortest acting), Bisoprolol. * **3rd Gen (Vasodilatory):** * *Non-selective:* **Labetalol** (blocks $\alpha_1$), **Carvedilol** (blocks $\alpha_1$ + antioxidant). * *Selective $\beta_1$:* **Nebivolol** (via NO), **Celiprolol** (via $\beta_2$ agonism). * **Labetalol** is the drug of choice for hypertension in pregnancy (preeclampsia). * **Carvedilol** is highly effective in reducing mortality in chronic heart failure. * **Esmolol** is administered IV for hypertensive emergencies and intraoperative tachycardia.

Question 744: What is the mechanism of action of cholestyramine?

A. Binds to bile acids (Correct Answer)
B. Decreases HMG-CoA
C. Increases excretion of cholesterol
D. Decreases utilization of cholesterol

Explanation: **Mechanism of Action: Cholestyramine** **Explanation of the Correct Answer (A):** Cholestyramine is a **Bile Acid Sequestrant** (Large, positively charged resin). It works in the small intestine by binding to negatively charged bile acids, forming an insoluble complex that is excreted in the feces. * **The Physiological Loop:** Normally, 95% of bile acids are reabsorbed via enterohepatic circulation. By preventing this reabsorption, cholestyramine forces the liver to synthesize new bile acids from hepatic cholesterol stores. * **The Result:** To get more cholesterol for this synthesis, the liver upregulates **LDL receptors**, leading to increased clearance of LDL from the plasma, thereby lowering serum cholesterol levels. **Why Other Options are Incorrect:** * **B (Decreases HMG-CoA):** This is the mechanism of **Statins** (e.g., Atorvastatin), which competitively inhibit HMG-CoA reductase, the rate-limiting enzyme in cholesterol synthesis. * **C (Increases excretion of cholesterol):** While it increases the excretion of *bile acids*, it does not directly excrete cholesterol itself. In fact, it may cause a compensatory increase in hepatic cholesterol synthesis. * **D (Decreases utilization of cholesterol):** Cholestyramine actually **increases** the hepatic utilization of cholesterol to replenish the depleted bile acid pool. **High-Yield Clinical Pearls for NEET-PG:** * **Side Effects:** Most common are GI-related (bloating, constipation, and steatorrhea). * **Drug Interactions:** It interferes with the absorption of fat-soluble vitamins (**A, D, E, K**) and acidic drugs like **Warfarin, Digoxin, and Thiazides**. (Rule: Take other drugs 1 hour before or 4 hours after the resin). * **Contraindication:** It can increase VLDL levels; therefore, it is contraindicated in patients with **Hypertriglyceridemia** (TG >300 mg/dL).

Question 745: Clonidine is indicated in which of the following conditions except?

A. Cardiac arrhythmias (Correct Answer)
B. Morphine withdrawal
C. Migraine
D. Hypertension

Explanation: **Explanation:** **Clonidine** is a centrally acting **$\alpha_2$-adrenergic agonist**. By stimulating presynaptic $\alpha_2$ receptors in the vasomotor center of the medulla, it decreases sympathetic outflow from the CNS, leading to a reduction in peripheral vascular resistance, heart rate, and blood pressure. **Why Cardiac Arrhythmias is the correct answer:** Clonidine has no established role in the management of cardiac arrhythmias. In fact, due to its sympatholytic effects, it can cause **bradycardia** and AV block as adverse effects. Therefore, it is not indicated for treating arrhythmias; rather, it may exacerbate certain conduction disturbances. **Analysis of Incorrect Options:** * **Hypertension:** This is the primary classical indication for Clonidine. It reduces blood pressure by decreasing central sympathetic tone. It is particularly useful in hypertensive urgencies. * **Morphine (Opioid) Withdrawal:** Clonidine is highly effective in suppressing the autonomic symptoms of opioid withdrawal (such as tachycardia, hypertension, and sweating) by compensating for the noradrenergic hyperactivity seen during withdrawal. * **Migraine:** Clonidine is used for the **prophylaxis** of migraine and vascular headaches, likely by reducing the reactivity of peripheral blood vessels to substances like norepinephrine. **High-Yield Clinical Pearls for NEET-PG:** * **Rebound Hypertension:** Sudden withdrawal of Clonidine can lead to a hypertensive crisis due to a massive release of catecholamines. It should always be tapered. * **Other Uses:** ADHD (in children), smoking cessation, and hot flashes in postmenopausal women. * **Side Effects:** Sedation and dry mouth (xerostomia) are the most common side effects. * **Diagnostic Test:** The **Clonidine Suppression Test** is used to diagnose Pheochromocytoma (Clonidine fails to suppress catecholamine levels in these patients).

Question 746: Beta-blockers are contraindicated in which of the following conditions?

A. Sick sinus syndrome (Correct Answer)
B. Angina pectoris
C. Acute aortic dissection
D. Post myocardial infarction

Explanation: **Explanation:** **Why Sick Sinus Syndrome (SSS) is the correct answer:** Beta-blockers are competitive antagonists at $\beta_1$-adrenergic receptors in the heart. Their primary electrophysiological effects include a decrease in the firing rate of the SA node (negative chronotropy) and a decrease in conduction velocity through the AV node (negative dromotropy). In **Sick Sinus Syndrome**, the SA node is already dysfunctional, leading to episodes of severe bradycardia or sinus arrest. Administering beta-blockers in this condition can dangerously exacerbate bradycardia or lead to complete heart block, making it a **strict contraindication**. **Why the other options are incorrect:** * **Angina Pectoris:** Beta-blockers are first-line agents. They reduce myocardial oxygen demand by lowering heart rate and contractility, thereby preventing ischemic episodes. * **Acute Aortic Dissection:** They are essential in management (often IV Esmolol or Labetalol) to reduce the "shear stress" ($dP/dt$) on the aortic wall by lowering both heart rate and blood pressure. * **Post Myocardial Infarction:** Beta-blockers are "cardioprotective." they reduce the risk of re-infarction, limit infarct size, and prevent post-MI arrhythmias and ventricular remodeling. **High-Yield Clinical Pearls for NEET-PG:** * **Other Contraindications:** Overt heart failure (acute decompensation), 2nd or 3rd-degree heart block, and severe bronchial asthma. * **Prinzmetal Angina:** Beta-blockers are contraindicated here as they can cause unopposed $\alpha$-mediated coronary vasoconstriction. * **Diabetes:** Use with caution as they can mask the tachycardic symptoms of hypoglycemia. * **Drug of Choice:** Esmolol is the shortest-acting beta-blocker (half-life ~9 mins), preferred for intraoperative hypertensive crises.

Question 747: Which PFOR inhibitor is used in the management of angina?

A. Nifedipine
B. Trimetazidine (Correct Answer)
C. Atenolol
D. Fasudil

Explanation: **Explanation:** **Trimetazidine** is the correct answer because it is a metabolic modulator that acts as a **Partial Fatty Acid Oxidation (p-FOX) inhibitor**. **Mechanism of Action:** Under normal conditions, the heart derives energy primarily from fatty acid oxidation. However, this process requires more oxygen per unit of ATP produced compared to glucose oxidation. Trimetazidine inhibits the enzyme **3-ketoacyl-CoA thiolase**, shifting the myocardial metabolism from fatty acid oxidation to **glucose oxidation**. This shift improves the efficiency of oxygen utilization, maintaining ATP production even under ischemic conditions without affecting heart rate or blood pressure. **Analysis of Incorrect Options:** * **A. Nifedipine:** A dihydropyridine Calcium Channel Blocker (CCB). It acts by causing peripheral vasodilation and coronary artery dilation, reducing afterload. It does not inhibit p-FOX. * **C. Atenolol:** A cardioselective $\beta_1$-blocker. It manages angina by reducing myocardial oxygen demand through a decrease in heart rate and contractility. * **D. Fasudil:** A **Rho-kinase inhibitor**. It is primarily used in the management of cerebral vasospasm following subarachnoid hemorrhage and is being studied for pulmonary hypertension, but it is not a p-FOX inhibitor. **High-Yield Clinical Pearls for NEET-PG:** * **Trimetazidine** is used as an add-on therapy for stable angina when first-line drugs are insufficient or not tolerated. * **Side Effects:** It can cause **Parkinsonian symptoms** (tremors, rigidity), gait disturbances, and restless leg syndrome, especially in elderly patients. * **Ranolazine** is another metabolic modulator used in angina; it acts by inhibiting the **late sodium current ($I_{Na}$)**, reducing calcium overload in ischemic myocytes.

Question 748: All of the following are true about losartan, except?

A. Angiotensin II antagonist
B. Causes hyperuricemia (Correct Answer)
C. Does not cause cough
D. Long acting metabolites

Explanation: **Explanation:** Losartan is a prototype **Angiotensin II Receptor Blocker (ARB)** that selectively antagonizes the $AT_1$ receptor. **Why Option B is the correct answer (The Exception):** Unlike most diuretics or other antihypertensives that may increase uric acid levels, **Losartan is unique because it is uricosuric.** It inhibits the URAT1 transporter in the proximal convoluted tubule of the kidney, leading to increased excretion of uric acid and a **decrease in serum uric acid levels (hypuricemia)**. Therefore, stating it causes hyperuricemia is incorrect. **Analysis of other options:** * **Option A:** Losartan is a competitive antagonist at the $AT_1$ receptor, blocking the effects of Angiotensin II such as vasoconstriction and aldosterone release. * **Option C:** Unlike ACE inhibitors, ARBs do not inhibit the breakdown of bradykinin or substance P in the lungs. Consequently, they **do not cause the dry cough** typically associated with ACE inhibitors. * **Option D:** While Losartan itself has a short half-life (approx. 2 hours), it is converted by CYP3A4 and CYP2C9 into a **long-acting active metabolite (E-3174)**. This metabolite is 10–40 times more potent and has a longer half-life (6–9 hours), contributing significantly to its 24-hour antihypertensive effect. **High-Yield Clinical Pearls for NEET-PG:** 1. **Uricosuric Property:** Losartan is the drug of choice for hypertensive patients with **Gout**. 2. **Fetotoxicity:** Like ACE inhibitors, ARBs are **contraindicated in pregnancy** (Teratogenic). 3. **Hyperkalemia:** ARBs can cause potassium retention; monitor levels when used with potassium-sparing diuretics. 4. **Inverse Agonism:** Some ARBs (like Olmesartan) act as inverse agonists, providing more complete blockade.

Question 749: Which of the following antihypertensives causes sedation?

A. Clonidine (Correct Answer)
B. Hydralazine
C. Losartan
D. Amlodipine

Explanation: **Explanation:** **Correct Answer: A. Clonidine** Clonidine is a centrally acting **$\alpha_2$-adrenergic agonist**. It stimulates $\alpha_2$ receptors in the nucleus tractus solitarius (NTS) of the medulla, leading to a decrease in sympathetic outflow from the vasomotor center. This reduction in sympathetic tone results in bradycardia and vasodilation. Because it crosses the blood-brain barrier and inhibits the release of norepinephrine in the CNS, it commonly causes **sedation** and mental depression. This "central effect" is a classic side effect frequently tested in exams. **Why the other options are incorrect:** * **B. Hydralazine:** A direct-acting vasodilator that primarily affects arterioles. Its common side effects include reflex tachycardia, fluid retention, and a Lupus-like syndrome, but not sedation. * **C. Losartan:** An Angiotensin II Receptor Blocker (ARB). It is generally well-tolerated; its most notable feature is the lack of cough (unlike ACE inhibitors). It does not cross the blood-brain barrier significantly to cause sedation. * **D. Amlodipine:** A Dihydropyridine Calcium Channel Blocker (CCB). Its primary side effects are peripheral edema, headache, and flushing due to potent peripheral vasodilation. **High-Yield Clinical Pearls for NEET-PG:** * **Rebound Hypertension:** Abrupt withdrawal of Clonidine can cause a hypertensive crisis due to a sudden surge in catecholamines. * **Other uses:** Clonidine is also used in opioid withdrawal, ADHD, and prophylaxis for migraine. * **Methyldopa:** Another centrally acting $\alpha_2$ agonist used in pregnancy-induced hypertension; it also causes sedation and a positive Coombs test.

Question 750: Which antihypertensive medication can be safely used in patients with gout and diabetes mellitus?

A. Thiazide
B. Enalapril (Correct Answer)
C. Propranolol
D. Diazoxide

Explanation: **Explanation:** The correct answer is **Enalapril (Option B)**. **Why Enalapril is correct:** Enalapril is an ACE inhibitor (ACEi). In patients with **Diabetes Mellitus**, ACE inhibitors are the drugs of choice because they provide **renoprotection** by dilating the efferent arteriole, thereby reducing intraglomerular pressure and slowing the progression of diabetic nephropathy. Regarding **Gout**, ACE inhibitors are metabolic neutral; they do not increase serum uric acid levels. In fact, some drugs in this class (like Losartan) have uricosuric properties, making them ideal for patients with hyperuricemia. **Why other options are incorrect:** * **Thiazides (Option A):** These are contraindicated or used with caution in both conditions. They cause **hyperuricemia** (by competing with uric acid for secretion in the proximal tubule) and **hyperglycemia** (by inhibiting insulin release and reducing peripheral glucose utilization). * **Propranolol (Option C):** This is a non-selective beta-blocker. It can mask the warning symptoms of hypoglycemia (tachycardia) in diabetics and may worsen peripheral vascular disease. It also tends to decrease urate excretion. * **Diazoxide (Option D):** This is a potent vasodilator used in hypertensive emergencies, but it is a known **K+ channel opener** that inhibits insulin release, leading to significant hyperglycemia. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of choice for HTN with Diabetes:** ACE inhibitors or ARBs (due to nephroprotective effects). * **Losartan** is the only ARB that significantly increases uric acid excretion (uricosuric), making it the best choice for HTN with Gout. * **Diuretics to avoid in Gout:** Thiazides and Loop diuretics (both cause hyperuricemia). * **Metabolic side effects of Thiazides:** Remember the "4 Hypers" (Hyperglycemia, Hyperuricemia, Hyperlipidemia, Hypercalcemia) and "3 Hypos" (Hypokalemia, Hyponatremia, Hypomagnesemia).

Practice by Chapter

Antihypertensive Agents

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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

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Thrombolytic Agents

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Drugs Used in Pulmonary Hypertension

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Drugs Used in Shock

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Cardiovascular Effects of Non-Cardiovascular Drugs

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