Cardiovascular Drugs Practice Questions

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

Block of exercise-induced tachycardia. **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.

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

Amiodarone. **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.

Q: Which drug is NOT useful in congestive heart failure?

Adrenaline. **Explanation:** In Congestive Heart Failure (CHF), the primary goal is to improve cardiac output while reducing the workload on an already failing heart. **Why Adrenaline (Option A) is the correct answer:** Adrenaline is a potent non-selective alpha and beta-adrenergic agonist. While it increases myocardial contractility (positive inotropy), it significantly increases heart rate (positive chronotropy) and peripheral vascular resistance. This leads to a massive increase in **myocardial oxygen demand** and **afterload**, which can precipitate arrhythmias and worsen myocardial ischemia in a failing heart. Therefore, it has no role in the long-term management of CHF. **Why the other options are used in CHF:** * **Digoxin (Option B):** A cardiac glycoside that inhibits the Na+/K+ ATPase pump, increasing intracellular calcium. It provides **positive inotropic** support and controls heart rate (especially in patients with concomitant Atrial Fibrillation). * **Hydrochlorothiazide (Option C):** A thiazide diuretic used to reduce fluid overload (preload), thereby relieving symptoms of pulmonary and peripheral edema. * **Enalapril (Option D):** An ACE inhibitor that is a cornerstone of CHF therapy. It reduces both **preload and afterload** and, most importantly, inhibits cardiac remodeling, which reduces mortality. **High-Yield Clinical Pearls for NEET-PG:** * **Mortality Benefit:** ACE inhibitors (Enalapril), Beta-blockers (Carvedilol, Metoprolol), Spironolactone, and ARNIs (Sacubitril/Valsartan) are proven to decrease mortality in CHF. * **Symptomatic Relief Only:** Digoxin and Diuretics improve symptoms and reduce hospitalizations but do **not** decrease mortality. * **Inotropic Support:** For acute decompensated heart failure, **Dobutamine** or **Milrinone** are preferred over Adrenaline as they are less likely to cause extreme tachycardia and vasoconstriction.

Q: What is the best time to administer long-term nitrates for nocturnal angina?

Evening. **Explanation:** The primary goal in administering long-term nitrates (like Isosorbide mononitrate or dinitrate) is to provide therapeutic coverage during the period of maximum symptoms while preventing **nitrate tolerance**. **1. Why Evening is Correct:** For patients with **nocturnal angina**, symptoms occur during sleep. Administering the dose in the **evening** ensures peak plasma concentrations during the night. More importantly, this schedule allows for a **"nitrate-free interval"** of 10–12 hours during the day. This interval is essential to restore the sulfhydryl groups required for nitric oxide production, thereby preventing the development of tolerance. **2. Analysis of Incorrect Options:** * **Early morning (A) & Noon (B):** These timings are appropriate for patients with *exertional angina* (angina of effort) to provide coverage during daytime activities. However, for nocturnal angina, the drug levels would be too low by nighttime to be effective. * **Late night (D):** While this provides coverage for the night, it shifts the nitrate-free interval into the late afternoon/evening, which may not be as physiologically optimal as an evening dose for preventing tolerance while maintaining nocturnal efficacy. **3. High-Yield NEET-PG Pearls:** * **Nitrate Tolerance:** Occurs due to the depletion of free sulfhydryl groups and "oxidative stress." It is best prevented by a daily nitrate-free interval of **at least 10–12 hours**. * **Drug of Choice:** For *acute* episodes of any angina, Sublingual Nitroglycerin is used. For *prophylaxis* of nocturnal angina, evening administration of long-acting nitrates is preferred. * **Contraindication:** Never co-administer nitrates with **Sildenafil** (PDE-5 inhibitors) as it can lead to severe, life-threatening hypotension.

Q: Compared to digoxin, what is a characteristic of digitoxin?

Longer plasma half-life. **Explanation:** The primary difference between Digoxin and Digitoxin lies in their lipid solubility. **Digitoxin** is highly lipid-soluble (non-polar), whereas Digoxin is relatively polar. **Why the correct answer is right:** Because Digitoxin is highly lipid-soluble, it undergoes extensive **enterohepatic circulation** and is heavily bound to plasma proteins. This results in a significantly **longer plasma half-life** (approximately 5–7 days) compared to Digoxin (approximately 36–40 hours). This long half-life means Digitoxin takes much longer to reach a steady state and longer to be eliminated from the body once discontinued. **Analysis of Incorrect Options:** * **A. Less plasma protein binding:** Incorrect. Digitoxin has very high protein binding (~95%), whereas Digoxin has low binding (~25%). * **C. Less oral absorption:** Incorrect. Due to its lipid solubility, Digitoxin is almost 100% absorbed from the gut. Digoxin absorption is variable (60–80%). * **D. More daily elimination:** Incorrect. Digitoxin has a lower daily elimination rate (~10%) compared to Digoxin (~33%) because of its long half-life and extensive reabsorption. **NEET-PG High-Yield Pearls:** * **Route of Elimination:** Digoxin is primarily excreted **renally** (unchanged), making it contraindicated in renal failure. Digitoxin is primarily metabolized by the **liver**, making it the preferred cardiac glycoside in patients with renal impairment. * **Volume of Distribution:** Digoxin has a very high $V_d$ because it binds strongly to skeletal muscle (Na+/K+ ATPase). * **Toxicity:** Hypokalemia predisposes to digoxin toxicity because K+ and digoxin compete for the same binding site on the Na+/K+ ATPase pump.

Q: Ezetimibe acts on which of the following targets?

Niemann-Pick C1-Like 1 (NPC1L1) protein. **Explanation:** **Mechanism of Action (Why C is correct):** Ezetimibe is a lipid-lowering agent that selectively inhibits the intestinal absorption of cholesterol and related phytosterols [1]. It specifically targets and binds to the **Niemann-Pick C1-Like 1 (NPC1L1) protein**, a transport protein located on the brush border membrane of enterocytes in the small intestine [2]. By blocking this transporter, Ezetimibe reduces the delivery of intestinal cholesterol to the liver, leading to a compensatory increase in LDL-receptor expression and a subsequent decrease in circulating LDL-C levels [1]. **Analysis of Incorrect Options:** * **A. Lipoprotein lipase (LPL):** This enzyme is activated by **Fibrates** (via PPAR-α) to increase the clearance of triglyceride-rich lipoproteins [5]. * **B. Peroxisome proliferator-activated receptor (PPAR):** PPAR-α is the target for **Fibrates** (e.g., Fenofibrate), while PPAR-γ is the target for **Thiazolidinediones** (e.g., Pioglitazone). * **D. HMG-CoA reductase:** This is the rate-limiting enzyme in hepatic cholesterol synthesis, which is inhibited by **Statins** [3], [4]. **High-Yield Clinical Pearls for NEET-PG:** * **Synergy:** Ezetimibe is frequently used as an "add-on" therapy to Statins. While Statins inhibit cholesterol *synthesis*, Ezetimibe inhibits cholesterol *absorption* (Dual inhibition) [1]. * **Effect on Lipids:** Its primary effect is a 15–20% reduction in **LDL**. It has minimal effects on HDL or Triglycerides [1]. * **Side Effects:** Generally well-tolerated; however, it may cause increased hepatic transaminases when used with statins. * **Vytorin:** A fixed-dose combination of Ezetimibe + Simvastatin.

Q: Which of the following is a non-selective vasopressin receptor antagonist?

Conivaptan. **Explanation:** Vasopressin (Antidiuretic Hormone) acts on three main receptor subtypes: **V1a** (vasoconstriction, platelet aggregation), **V1b** (ACTH release), and **V2** (water reabsorption in renal collecting ducts). Drugs that block these receptors are known as "vaptans." **Why Conivaptan is correct:** **Conivaptan** is a **non-selective (dual) V1a and V2 receptor antagonist**. By blocking V2 receptors, it promotes aquaresis (solute-free water excretion), and by blocking V1a receptors, it reduces peripheral vascular resistance. It is administered intravenously and is primarily used for the treatment of euvolemic and hypervolemic hyponatremia (e.g., SIADH). **Analysis of incorrect options:** * **Tolvaptan (Option A):** This is a **selective oral V2 receptor antagonist**. It is the most commonly used vaptan for chronic hyponatremia but carries a "black box" warning for potential hepatotoxicity if used for more than 30 days. * **Relcovaptan (Option C):** This is a **selective V1a receptor antagonist**. It has been investigated for conditions like Raynaud’s disease and dysmenorrhea but is not used for hyponatremia. * **Lixivaptan (Option D):** Like tolvaptan, this is a **selective V2 receptor antagonist** (currently under clinical investigation). **High-Yield NEET-PG Pearls:** 1. **Conivaptan** = Dual V1a/V2 blocker (IV only). 2. **Tolvaptan** = Selective V2 blocker (Oral). 3. **Indication:** Vaptans are the treatment of choice for **SIADH** when fluid restriction fails. 4. **Caution:** Rapid correction of hyponatremia with vaptans can lead to **Osmotic Demyelination Syndrome (Central Pontine Myelinolysis)**. Always monitor serum sodium levels closely.

Q: Which pharmacological stressor is used in PET scans to detect cardiac function?

Dobutamine. **Explanation:** **Dobutamine** is the correct answer because it is a potent **$\beta_1$-adrenergic agonist** used as a pharmacological stressor in cardiac imaging, including PET scans and stress echocardiography [2]. In patients unable to perform physical exercise, Dobutamine mimics the effects of exercise by increasing myocardial oxygen demand through its positive inotropic (contractility) and chronotropic (heart rate) effects [3]. This "stresses" the heart, allowing clinicians to identify areas of inducible ischemia or hibernating myocardium. **Analysis of Incorrect Options:** * **A. Dopamine:** While it has $\beta_1$ effects at moderate doses, it primarily acts on dopamine receptors and $\alpha_1$ receptors at higher doses, causing systemic vasoconstriction which is not ideal for controlled cardiac stress testing. * **C. Droxidopa:** This is a synthetic precursor of norepinephrine used primarily to treat neurogenic orthostatic hypotension; it has no role in cardiac stress imaging. * **D. Noradrenaline:** This is a potent $\alpha_1$ agonist. It causes significant peripheral vasoconstriction and reflex bradycardia, making it unsuitable for inducing controlled cardiac stress for diagnostic purposes. **High-Yield Clinical Pearls for NEET-PG:** * **Pharmacological Stressors:** Apart from Dobutamine (an inotrope), **Vasodilators** like **Adenosine, Dipyridamole, and Regadenoson** are also used in PET/SPECT scans [2]. They work by causing "coronary steal" rather than increasing heart rate. * **PET Radiopharmaceutical:** The most common tracer used for myocardial perfusion PET is **Rubidium-82** or **N-13 Ammonia**, while **18F-FDG** is used to assess myocardial viability [1]. * **Antidote:** If a patient develops severe arrhythmia or ischemia during a Dobutamine stress test, **Esmolol** (a short-acting $\beta$-blocker) is the drug of choice to reverse the effects.

Question 1

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

Accepted Answer

Block of exercise-induced tachycardia

Answer

Dilation of constricted coronary vessels

Answer

Increased cardiac force

Answer

Increased resting heart rate

Question 2

Which of the following drugs has the maximum half-life?

Accepted Answer

Amiodarone

Answer

Adenosine

Answer

Esmolol

Answer

Lidocaine

Question 3

Which drug is NOT useful in congestive heart failure?

Accepted Answer

Adrenaline

Answer

Digoxin

Answer

Hydrochlorothiazide

Answer

Enalapril

Question 4

Which of the following agents decreases preload?

Accepted Answer

Nitroglycerine

Answer

Hydralazine

Answer

Nifedipine

Answer

Losartan

Question 5

What is the best time to administer long-term nitrates for nocturnal angina?

Accepted Answer

Evening

Answer

Early morning

Answer

Noon

Answer

Late night

Question 6

Compared to digoxin, what is a characteristic of digitoxin?

Accepted Answer

Longer plasma half-life

Answer

Less plasma protein binding

Answer

Less oral absorption

Answer

More daily elimination

Question 7

Ezetimibe acts on which of the following targets?

Accepted Answer

Niemann-Pick C1-Like 1 (NPC1L1) protein

Answer

Lipoprotein lipase (LPL)

Answer

Peroxisome proliferator-activated receptor (PPAR)

Answer

HMG-CoA reductase inhibitor

Question 8

Which local anesthetic agent is also used as an antiarrhythmic agent?

Accepted Answer

Lignocaine

Answer

Bupivacaine

Answer

Cocaine

Answer

Chlorprocaine

Question 9

Which of the following is a non-selective vasopressin receptor antagonist?

Accepted Answer

Conivaptan

Answer

Tolvaptan

Answer

Relcovaptan

Answer

Lixivaptan

Question 10

Which pharmacological stressor is used in PET scans to detect cardiac function?

Accepted Answer

Dobutamine

Answer

Dopamine

Answer

Droxidopa

Answer

Noradrenaline

Cardiovascular Drugs — MCQs

Cardiovascular Drugs — MCQs

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