Cardiovascular Drugs — MCQs

Cardiovascular Drugs Indian Medical PG Practice Questions and MCQs

Question 361: Which of the following drugs is added along with beta-blockers to eliminate undesirable side effects caused by them while treating Angina?

A. Diltiazem
B. Ivabradine
C. Nitrates (Correct Answer)
D. Verapamil

Explanation: ### Explanation The combination of **Beta-blockers and Nitrates** is a classic pharmacological strategy in the management of stable angina because they exert **synergistic effects** while mutually canceling out each other’s adverse hemodynamic consequences. **Why Nitrates are the correct choice:** 1. **Reflex Tachycardia:** Nitrates cause peripheral vasodilation, which can trigger a compensatory reflex tachycardia. Beta-blockers prevent this by slowing the heart rate. 2. **Ventricular Wall Tension:** Beta-blockers increase the Left Ventricular End-Diastolic Volume (LVEDV) and fiber length (due to increased filling time), which increases myocardial oxygen demand. Nitrates, through venodilation (preload reduction), decrease LVEDV and heart size, thereby counteracting this effect. 3. **Combined Benefit:** Together, they significantly reduce myocardial oxygen demand more effectively than either drug alone. **Why other options are incorrect:** * **Diltiazem & Verapamil (Non-dihydropyridine CCBs):** These drugs also decrease heart rate and AV conduction. Combining them with beta-blockers is generally **contraindicated** (or requires extreme caution) due to the high risk of severe bradycardia, heart block, or additive negative inotropic effects leading to heart failure. * **Ivabradine:** While it can be added to beta-blockers for heart rate control in chronic stable angina, it does not specifically counteract the "undesirable side effects" (like increased LVEDV) caused by beta-blockers in the way nitrates do. **High-Yield Clinical Pearls for NEET-PG:** * **Goal of Combination:** To decrease oxygen demand by reducing heart rate, contractility (Beta-blockers), and preload (Nitrates). * **Contraindication:** Never combine Beta-blockers with Verapamil/Diltiazem in patients with conduction defects. * **Nifedipine (DHP-CCB):** Can be combined with Beta-blockers; the Beta-blocker prevents the reflex tachycardia typically caused by Nifedipine.

Question 362: Which of the following statements about prasugrel is true when compared to clopidogrel?

A. Prasugrel is slower acting than clopidogrel.
B. Due to a higher risk of bleeding, prasugrel is contraindicated in patients with a history of stroke. (Correct Answer)
C. Prasugrel is a reversible antagonist of ADP receptors.
D. Prasugrel is effective orally, unlike clopidogrel.

Explanation: **Explanation:** Prasugrel and clopidogrel are both **thienopyridine** derivatives that act as **irreversible P2Y12 receptor antagonists**, inhibiting ADP-induced platelet aggregation. **Why Option B is Correct:** Prasugrel is a more potent antiplatelet agent than clopidogrel. While this increases efficacy in preventing ischemic events, it significantly increases the risk of major bleeding. Large-scale trials (TRITON-TIMI 38) demonstrated a significantly higher risk of intracranial hemorrhage in patients with a prior history of cerebrovascular events. Therefore, prasugrel is **absolutely contraindicated** in patients with a history of **stroke or Transient Ischemic Attack (TIA)**. **Analysis of Incorrect Options:** * **Option A:** Prasugrel is a **faster-acting** drug than clopidogrel. It is more efficiently converted to its active metabolite in a single metabolic step, whereas clopidogrel requires a two-step hepatic activation. * **Option C:** Prasugrel is an **irreversible** antagonist. Among P2Y12 inhibitors, **Ticagrelor** and **Cangrelor** are the ones that bind reversibly. * **Option D:** Both prasugrel and clopidogrel are **prodrugs** and are administered **orally**. (Cangrelor is the only P2Y12 inhibitor administered intravenously). **High-Yield NEET-PG Pearls:** * **Metabolism:** Clopidogrel activation is highly dependent on the **CYP2C19** enzyme. Genetic polymorphisms in this enzyme can lead to "clopidogrel resistance." Prasugrel is less affected by these polymorphisms. * **Contraindications for Prasugrel:** 1. History of Stroke/TIA, 2. Age >75 years (relative), 3. Body weight <60 kg (requires dose reduction). * **Clinical Use:** Prasugrel is primarily indicated for patients with Acute Coronary Syndrome (ACS) undergoing Percutaneous Coronary Intervention (PCI).

Question 363: Which of the following drugs inhibits the enzyme responsible for the initial step of cholesterol synthesis?

A. Lovastatin (Correct Answer)
B. Gemfibrozil
C. Probucol
D. Cholestyramine

Explanation: **Correct Option: A. Lovastatin**The "initial" or rate-limiting step of cholesterol biosynthesis is the conversion of **HMG-CoA to Mevalonate** [2]. This reaction is catalyzed by the enzyme **HMG-CoA reductase** [2]. Lovastatin belongs to the 'Statin' class of drugs, which are competitive inhibitors of this enzyme [1, 2]. By inhibiting this early step, statins reduce intracellular cholesterol levels, leading to the compensatory up-regulation of LDL receptors on hepatocytes and a subsequent decrease in plasma LDL levels [1, 2].**Analysis of Incorrect Options:** * **B. Gemfibrozil:** This is a Fibrate. Its primary mechanism is the activation of **PPAR-α** (Peroxisome Proliferator-Activated Receptor-alpha), which increases the activity of lipoprotein lipase (LPL), primarily lowering triglycerides rather than inhibiting cholesterol synthesis.* **C. Probucol:** This drug acts by increasing the rate of LDL catabolism and has antioxidant properties (preventing the oxidation of LDL). It does not inhibit the HMG-CoA reductase enzyme.* **D. Cholestyramine:** This is a **Bile Acid Sequestrant**. It binds to bile acids in the intestine, preventing their enterohepatic circulation. This forces the liver to use more cholesterol to synthesize new bile acids, thereby lowering systemic cholesterol indirectly.**High-Yield NEET-PG Pearls:** * **Rate-limiting enzyme:** HMG-CoA Reductase.* **Pleiotropic effects of Statins:** Beyond lowering lipids, they improve endothelial function, stabilize atherosclerotic plaques, and have anti-inflammatory effects [1].* **Adverse Effects:** Myopathy (monitored via CPK levels) and hepatotoxicity (monitored via LFTs).* **Contraindication:** Statins are strictly contraindicated in **pregnancy** (Teratogenic).

Question 364: All of the following statements about nasiritide are true except?

A. It is a BNP analogue
B. It can be used in decompensated CHF
C. It can be administered orally (Correct Answer)
D. It causes loss of Na+ in the urine

Explanation: **Explanation:** **Nesiritide** is a recombinant form of human **B-type Natriuretic Peptide (BNP)**. The correct answer is **C** because Nesiritide is a polypeptide; like insulin or other proteins, it would be degraded by gastrointestinal enzymes if taken orally. Therefore, it must be administered via **intravenous (IV) infusion**. **Analysis of Options:** * **Option A (BNP analogue):** This is true. It is synthesized using recombinant DNA technology and is identical to the endogenous hormone secreted by the ventricular myocardium in response to stretch. * **Option B (Used in decompensated CHF):** This is true. It is indicated for the management of acutely decompensated heart failure (ADHF) in patients who have dyspnea at rest. It reduces pulmonary capillary wedge pressure (PCWP) and systemic vascular resistance. * **Option D (Loss of Na+ in urine):** This is true. As a natriuretic peptide, it stimulates guanylyl cyclase, increasing cGMP. This leads to potent **natriuresis** (sodium excretion) and diuresis, alongside vasodilation. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism:** Increases cGMP in vascular smooth muscle and kidney cells. * **Hemodynamic Effects:** Acts as a balanced vasodilator (dilates both arterioles and veins), reducing both **preload and afterload**. * **Major Side Effect:** The most common dose-limiting adverse effect is **hypotension**. Some studies also suggest a risk of worsening renal function. * **Half-life:** It has a short half-life of approximately 18–20 minutes.

Question 365: Which of the following drugs is a potassium channel activator?

A. Trimetazidine
B. Ivabradine
C. Nicorandil (Correct Answer)
D. Detanonoate

Explanation: **Explanation:** **Nicorandil** is the correct answer because it possesses a unique dual mechanism of action. It acts as a **K+ATP channel activator** (potassium channel opener) and also contains a nitrate moiety. By opening ATP-sensitive potassium channels in the vascular smooth muscle, it causes K+ efflux, leading to hyperpolarization and subsequent vasodilation of the **arterioles**. Simultaneously, its nitrate component increases cGMP, leading to **venodilation**. This dual action reduces both afterload and preload, making it highly effective in stable angina. **Analysis of Incorrect Options:** * **Trimetazidine:** This is a metabolic modulator. It acts as a **p-FOX inhibitor** (partial fatty acid oxidase inhibitor). By shifting the myocardial metabolism from fatty acids to glucose, it reduces oxygen demand without affecting hemodynamics. * **Ivabradine:** This is a selective **"Funny" current (If) blocker** in the SA node. It reduces heart rate without affecting myocardial contractility or blood pressure. * **Detanonoate:** This is a **Nitric Oxide (NO) donor** used primarily in experimental pharmacology for the controlled release of NO; it is not a potassium channel activator. **High-Yield Clinical Pearls for NEET-PG:** * **Nicorandil Side Effect:** A characteristic and high-yield side effect is **painful mucosal ulcerations** (anal, oral, or GI ulcers). * **K+ Channel Openers:** Other drugs in this class include **Minoxidil** (used for hypertension and alopecia) and **Diazoxide** (used for insulinoma/hypoglycemia). * **Preconditioning:** Nicorandil mimics "ischemic preconditioning," providing a cardioprotective effect during episodes of ischemia.

Question 366: Which of the following statements regarding Digoxin is true?

A. It acts by inhibiting phosphodiesterase 3.
B. Dose reduction is not required in liver failure. (Correct Answer)
C. Hyperkalemia predisposes to Digoxin toxicity.
D. Atrial flutter is the most characteristic arrhythmia caused by Digoxin toxicity.

Explanation: ### Explanation **Correct Option: B. Dose reduction is not required in liver failure.** Digoxin is primarily a water-soluble drug. Approximately **60–80% of the drug is excreted unchanged by the kidneys** [1] via glomerular filtration and tubular secretion (P-glycoprotein). Since it undergoes minimal hepatic metabolism [1], its clearance is independent of liver function. Therefore, dose reduction is mandatory in renal failure [1] but **not required in liver failure**. **Why other options are incorrect:** * **Option A:** Digoxin acts by inhibiting the **Na+/K+ ATPase pump** on the cardiac myocyte membrane. This leads to an increase in intracellular sodium, which subsequently slows the Na+/Ca2+ exchanger, increasing intracellular calcium and myocardial contractility [1]. Phosphodiesterase 3 (PDE3) inhibitors are drugs like Milrinone and Amrinone. * **Option C:** **Hypokalemia** (not hyperkalemia) predisposes to Digoxin toxicity. Potassium and Digoxin compete for the same binding site on the Na+/K+ ATPase pump. Low potassium levels allow more Digoxin to bind, leading to toxicity [2]. (Note: Hypercalcemia and hypomagnesemia also increase toxicity). * **Option D:** The most characteristic (pathognomonic) arrhythmia of Digoxin toxicity is **Atrial Tachycardia with AV block**. The most common arrhythmia overall is **Ventricular Bigeminy**. Atrial flutter is actually a condition where Digoxin is used for rate control. **High-Yield Clinical Pearls for NEET-PG:** 1. **Therapeutic Window:** Narrow (0.5–2.0 ng/mL) [1]. 2. **ECG Changes (Therapeutic):** "Reverse Tick" or "Sagging" ST-segment depression (Salvador Dali’s mustache sign). 3. **Visual Side Effect:** Xanthopsia (yellowish-green vision). 4. **Antidote:** Digoxin-specific antibody fragments (**DigiFab**). 5. **Drug Interaction:** **Quinidine, Verapamil, and Amiodarone** increase Digoxin levels by displacing it from tissue binding sites and reducing renal clearance [1].

Question 367: Nitric oxide acts via which second messenger?

A. cAMP
B. cGMP (Correct Answer)
C. Calcium
D. Potassium

Explanation: ### Explanation **1. Why cGMP is the Correct Answer:** Nitric Oxide (NO) is a potent endogenous vasodilator. It diffuses across the cell membrane of vascular smooth muscle cells and binds to the heme moiety of the enzyme **Soluble Guanylyl Cyclase (sGC)**. This activation leads to the conversion of GTP into **cyclic Guanosine Monophosphate (cGMP)**. Increased levels of cGMP activate Protein Kinase G (PKG), which leads to dephosphorylation of myosin light chains and sequestration of intracellular calcium, ultimately resulting in **smooth muscle relaxation**. **2. Why Other Options are Incorrect:** * **A. cAMP:** This is the second messenger for drugs like Beta-agonists (e.g., Dobutamine) and PDE-3 inhibitors (e.g., Milrinone). While it also causes vasodilation, it is not the pathway for NO. * **C. Calcium:** Calcium is generally a messenger for **contraction** (via Calmodulin) rather than relaxation. NO actually works to *decrease* cytosolic calcium levels. * **D. Potassium:** While NO can indirectly lead to the opening of K+ channels (causing hyperpolarization), it does not act as a second messenger itself. **3. High-Yield Clinical Pearls for NEET-PG:** * **Nitrates & PDE-5 Inhibitors:** Drugs like Sildenafil (PDE-5 inhibitor) prevent the breakdown of cGMP. Combining them with Nitrates (NO donors) leads to an exaggerated accumulation of cGMP, causing severe, life-threatening hypotension. * **Endogenous Source:** NO is synthesized from the amino acid **L-Arginine** by the enzyme Nitric Oxide Synthase (NOS). * **Inhaled NO:** Used clinically in the management of Persistent Pulmonary Hypertension of the Newborn (PPHN) because it causes selective pulmonary vasodilation. * **Nitroprusside:** Acts by spontaneously releasing NO, unlike Nitroglycerin which requires enzymatic bioactivation.

Question 368: Inotropic drugs act on which receptors?

A. Alpha1
B. Alpha2
C. Beta1 (Correct Answer)
D. Beta2

Explanation: Inotropic drugs increase the force of myocardial contraction. The primary mechanism for most sympathomimetic inotropes (like Dobutamine and Dopamine) involves the stimulation of **Beta-1 (β₁) receptors** [1]. **1. Why Beta-1 is Correct:** β₁ receptors are predominantly located in the myocardium [1]. Stimulation of these G-protein coupled receptors activates Adenylyl Cyclase, increasing intracellular cAMP [3]. This leads to the activation of Protein Kinase A (PKA), which opens L-type calcium channels and promotes calcium release from the sarcoplasmic reticulum [1]. The resulting increase in intracellular calcium enhances actin-myosin cross-bridging, leading to a **positive inotropic effect** (increased contractility) [1]. **2. Why Other Options are Incorrect:** * **Alpha-1 (α₁):** Primarily located on vascular smooth muscle [1]. Stimulation causes **vasoconstriction**, increasing systemic vascular resistance (afterload), but has minimal direct effect on cardiac contractility [1]. * **Alpha-2 (α₂):** These are mainly presynaptic receptors in the CNS [1]. Stimulation inhibits norepinephrine release, leading to **sympatholysis** (e.g., Clonidine), which can actually decrease heart rate and blood pressure [1]. * **Beta-2 (β₂):** Predominantly located in the bronchioles and skeletal muscle blood vessels [1]. Stimulation causes **bronchodilation and vasodilation** [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Dobutamine:** The drug of choice for cardiogenic shock; it is a relatively selective β₁ agonist. * **Digoxin:** A non-sympathomimetic inotrope that acts by inhibiting the **Na+/K+ ATPase pump**, indirectly increasing intracellular calcium [2]. * **Milrinone:** A PDE-3 inhibitor that prevents cAMP breakdown, providing inotropic effects and vasodilation ("Inodilator"). * **Beta-1 Location Mnemonic:** You have **1** Heart (β₁) and **2** Lungs (β₂).

Question 369: Which of the following drugs is used to control hypertension emergencies?

A. Diazoxide
B. Hydralazine
C. Nitroglycerine
D. Sodium nitroprusside (Correct Answer)

Explanation: **Explanation:** **Sodium Nitroprusside** is the drug of choice for hypertensive emergencies because of its rapid onset (seconds) and short duration of action (1-2 minutes). It is a balanced vasodilator that acts by releasing Nitric Oxide (NO), which stimulates guanylyl cyclase to increase cGMP. This results in the relaxation of both **arterioles and venules**, leading to an immediate reduction in both preload and afterload. Its effects are easily titratable via continuous IV infusion, allowing for precise control of blood pressure. **Analysis of Incorrect Options:** * **Diazoxide (A):** Once used for emergencies, it is now largely obsolete. It is a K+ channel opener that causes profound arteriolar dilation but can lead to reflex tachycardia and hyperglycemia (by inhibiting insulin release). * **Hydralazine (B):** Primarily an arteriolar vasodilator. While used in hypertension, its onset is slower and its effects are less predictable than nitroprusside. It is, however, a preferred drug for **hypertension in pregnancy (Preeclampsia/Eclampsia)**. * **Nitroglycerine (C):** Acts predominantly as a **venodilator**. While used in hypertensive crises associated with acute coronary syndrome or acute heart failure, it is not the universal first-line agent for general hypertensive emergencies compared to nitroprusside or labetalol. **High-Yield Clinical Pearls for NEET-PG:** * **Cyanide Toxicity:** Sodium nitroprusside contains cyanide groups. Prolonged infusion can lead to cyanide/thiocyanate toxicity. The antidote is **Sodium Thiosulfate** or **Hydroxocobalamin**. * **Light Sensitivity:** Nitroprusside solution is unstable in light and must be wrapped in opaque foil. * **DOC for Aortic Dissection:** Esmolol or Labetalol (to reduce heart rate and shear stress). * **DOC for Hypertensive Emergency with Pheochromocytoma:** Phentolamine.

Question 370: What is the recommended dose of streptokinase for myocardial infarction?

A. 0.15 million units
B. 1.5 million units (Correct Answer)
C. 15 million units
D. 150 million units

Explanation: ### Explanation **Streptokinase** is a first-generation fibrinolytic agent derived from Beta-hemolytic Streptococci. In the management of Acute ST-Elevation Myocardial Infarction (STEMI), it acts by forming a complex with plasminogen, which then converts free plasminogen into active plasmin to degrade fibrin clots. **Why 1.5 million units is correct:** The standard, evidence-based dose for systemic thrombolysis in MI is **1.5 million units (MU)**. This dose is typically diluted in 100 ml of Normal Saline or 5% Dextrose and administered via **intravenous infusion over 30–60 minutes**. This concentration is optimized to achieve effective clot lysis while balancing the high risk of systemic bleeding. **Analysis of Incorrect Options:** * **0.15 million units:** This dose is sub-therapeutic for systemic thrombolysis in MI. However, lower doses (approx. 250,000 units) are sometimes used as a "loading dose" in pulmonary embolism or for intracoronary administration, but not for standard IV thrombolysis in MI. * **15 million and 150 million units:** These doses are excessively high and would lead to catastrophic, fatal systemic hemorrhage. **High-Yield Clinical Pearls for NEET-PG:** 1. **Mechanism:** It is a **non-fibrin specific** thrombolytic (unlike Alteplase/Tenecteplase), meaning it causes systemic depletion of fibrinogen. 2. **Antigenicity:** Because it is a bacterial protein, it is highly antigenic. It can cause **Type I Hypersensitivity (Anaphylaxis)**. 3. **The "Once in a Lifetime" Rule:** Due to the development of neutralizing antibodies, streptokinase should **not** be repeated if a patient has received it within the last 6 months to 1 year, as it will be ineffective and may cause severe allergic reactions. 4. **Side Effect:** Significant **hypotension** is a common side effect during infusion; if this occurs, the infusion rate should be slowed.

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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