Cardiovascular Drugs — MCQs

Cardiovascular Drugs Indian Medical PG Practice Questions and MCQs

Question 801: Ezetimibe acts by

A. Enhancing excretion of bile acids
B. Decreasing absorption of cholesterol (Correct Answer)
C. Inhibiting HMG CoA reductase
D. Inhibiting intracellular lipase

Explanation: **Explanation:** **Ezetimibe** is a cholesterol absorption inhibitor that specifically targets the **Niemann-Pick C1-Like 1 (NPC1L1)** transport protein located on the brush border of enterocytes in the small intestine. By inhibiting this transporter, it reduces the delivery of dietary and biliary cholesterol to the liver. This leads to an upregulation of LDL receptors on hepatocytes, subsequently decreasing circulating LDL-C levels. **Analysis of Options:** * **Option A (Enhancing excretion of bile acids):** This is the mechanism of **Bile Acid Sequestrants** (e.g., Cholestyramine, Colestipol). They bind bile acids in the gut, preventing enterohepatic circulation and forcing the liver to use cholesterol to synthesize new bile acids. * **Option B (Correct):** Ezetimibe directly inhibits the intestinal absorption of cholesterol. * **Option C (Inhibiting HMG CoA reductase):** This is the mechanism of **Statins** (e.g., Atorvastatin). Statins inhibit the rate-limiting step of endogenous cholesterol synthesis. * **Option D (Inhibiting intracellular lipase):** This refers to the mechanism of **Fibrates** (which stimulate lipoprotein lipase) or **Niacin** (which inhibits hormone-sensitive lipase in adipose tissue). **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*, leading to a potent dual effect. * **Vytorin:** A fixed-dose combination of Ezetimibe + Simvastatin. * **Side Effects:** Generally well-tolerated; however, it may cause a mild increase in hepatic transaminases when used with statins. * **Key Target:** Always remember **NPC1L1** for Ezetimibe; it is a common "one-liner" question in PG exams.

Question 802: Thrombolytic therapy with streptokinase is contraindicated in all of the following conditions EXCEPT?

A. Supraventricular tachycardia (Correct Answer)
B. Recent trauma
C. Recent cerebral bleeding
D. Recent surgery

Explanation: **Explanation:** The core principle of thrombolytic therapy (fibrinolytics) is the systemic activation of plasminogen to plasmin, which dissolves fibrin clots [2]. Because this process impairs global hemostasis, any condition with a high risk of life-threatening hemorrhage is a contraindication. **1. Why Supraventricular Tachycardia (SVT) is the Correct Answer:** SVT is an arrhythmia, not a bleeding diathesis or a structural lesion. It does not involve a risk of hemorrhage. While thrombolytics are not a treatment for SVT (which is managed with adenosine or cardioversion), the presence of SVT does not prevent the use of streptokinase if the patient concurrently suffers from an indicated condition, such as an acute ST-elevation myocardial infarction (STEMI) [2]. **2. Why the Other Options are Incorrect (Contraindications):** * **Recent Trauma & Recent Surgery (Options B & D):** These are **relative to absolute contraindications**. Surgical wounds or traumatic injuries rely on stable fibrin plugs for healing. Streptokinase would dissolve these plugs, leading to massive internal or site-specific hemorrhage [1]. * **Recent Cerebral Bleeding (Option C):** This is an **absolute contraindication**. Thrombolytics can expand a recent intracranial hemorrhage or convert an ischemic stroke into a hemorrhagic one, which is often fatal [1]. **NEET-PG High-Yield Pearls:** * **Mechanism:** Streptokinase is a non-enzymatic protein derived from B-hemolytic streptococci; it forms a complex with plasminogen to activate it [2]. * **Antigenicity:** Because it is bacterial, it is antigenic. It can cause **anaphylaxis** and should not be reused within 6–12 months due to neutralizing antibodies. * **Absolute Contraindications for Thrombolysis:** 1. Any prior intracranial hemorrhage. 2. Known structural cerebral vascular lesion (e.g., AV malformation). 3. Ischemic stroke within 3 months. 4. Active internal bleeding (excluding menses) [1]. 5. Suspected aortic dissection.

Question 803: A 55-year-old male with a history of type 2 diabetes mellitus, managed with oral hypoglycemic agents, presents with a blood pressure reading of 164/102 mm Hg. What is the most suitable antihypertensive drug for this patient?

A. Propranolol
B. Enalapril (Correct Answer)
C. Clonidine
D. Hydrochlorothiazide

Explanation: **Explanation:** **1. Why Enalapril is the Correct Choice:** In patients with **Diabetes Mellitus (DM)** and hypertension, **ACE inhibitors (like Enalapril)** or ARBs are the first-line agents of choice. The underlying medical concept is **renoprotection**. Diabetes is a leading cause of chronic kidney disease (Diabetic Nephropathy). ACE inhibitors dilate the efferent arterioles of the glomerulus more than the afferent arterioles, reducing intraglomerular pressure. This action slows the progression of albuminuria and preserves renal function, regardless of the blood pressure-lowering effect. **2. Why the Other Options are Incorrect:** * **Propranolol (Beta-blocker):** Generally avoided as a first-line agent in diabetics because it can mask the autonomic symptoms of hypoglycemia (like tachycardia and tremors) and may impair glucose tolerance by inhibiting insulin release. * **Clonidine (Centrally acting alpha-2 agonist):** This is not a first-line drug for essential hypertension. It is associated with side effects like sedation and dry mouth, and it offers no specific metabolic or renal benefits for diabetic patients. * **Hydrochlorothiazide (Thiazide Diuretic):** While effective, thiazides can cause hyperglycemia (by inhibiting insulin secretion and decreasing peripheral glucose utilization) and hyperlipidemia, making them less ideal than ACE inhibitors for diabetic patients. **Clinical Pearls for NEET-PG:** * **Drug of Choice (DOC):** ACE inhibitors/ARBs are DOC for HTN in patients with DM, Proteinuria, CKD, and Heart Failure. * **Side Effect Profile:** A common side effect of Enalapril is a **dry cough** (due to increased bradykinin). If a patient develops a cough, switch them to an **ARB (e.g., Losartan)**. * **Contraindication:** ACE inhibitors are strictly **contraindicated in pregnancy** (teratogenic) and in patients with **bilateral renal artery stenosis**.

Question 804: Which of the following drugs will decrease heart rate in a patient with a normal heart rate but will have little effect on heart rate in a cardiac transplant recipient?

A. Adrenaline
B. Noradrenaline
C. Isoproterenol
D. Phenylephrine (Correct Answer)

Explanation: ### Explanation The key to solving this question lies in understanding the difference between **direct drug effects** and **reflex autonomic responses**, particularly in the context of a **denervated heart**. **1. Why Phenylephrine is Correct:** Phenylephrine is a selective **$\alpha_1$-adrenergic agonist**. It causes potent vasoconstriction, leading to a significant increase in peripheral vascular resistance and blood pressure. * **In a normal heart:** The rise in blood pressure triggers the **baroreceptor reflex**, which increases vagal (parasympathetic) tone to the heart, resulting in **reflex bradycardia** (decreased heart rate). * **In a cardiac transplant recipient:** The transplanted heart is **denervated**. Since the vagus nerve is severed during surgery, the baroreceptor reflex arc is broken. Therefore, the drug-induced rise in blood pressure cannot trigger a reflex slowing of the heart. Phenylephrine has no significant direct $\beta_1$ activity, so the heart rate remains largely unchanged. **2. Why the Other Options are Incorrect:** * **Adrenaline (Epinephrine):** Acts on $\beta_1$ receptors directly. It would increase the heart rate in both normal and transplanted hearts due to its direct positive chronotropic effect. * **Noradrenaline (Norepinephrine):** While it causes reflex bradycardia in normal individuals (due to $\alpha_1$ effects), it also possesses direct $\beta_1$ agonist activity. In a transplant recipient, the direct $\beta_1$ effect would dominate, likely increasing the heart rate. * **Isoproterenol:** A pure $\beta_1$ and $\beta_2$ agonist. It directly increases heart rate in both scenarios. **3. High-Yield Clinical Pearls for NEET-PG:** * **Denervated Heart:** A transplanted heart lacks autonomic innervation. It maintains a higher-than-normal resting heart rate (90–100 bpm) because it lacks inhibitory vagal tone. * **Atropine:** This drug will **not** increase the heart rate in a cardiac transplant patient because its mechanism (parasympathetic blockade) requires an intact vagus nerve. * **Reflex Bradycardia:** Always look for drugs with pure $\alpha_1$ agonism (e.g., Phenylephrine, Methoxamine) to trigger this response.

Question 805: ACE inhibitors should not be used concurrently with which of the following agents?

A. Amiloride
B. Calcium Channel Blockers (CCB)
C. Spironolactone (Correct Answer)
D. Thiazides

Explanation: **Explanation:** The correct answer is **Spironolactone**. **1. Why Spironolactone is the correct answer:** The primary concern when combining ACE inhibitors (ACEIs) with Spironolactone is the risk of **severe hyperkalemia**. ACE inhibitors block the production of Angiotensin II, leading to decreased Aldosterone secretion. Since Aldosterone normally promotes potassium excretion, ACEIs cause potassium retention. Spironolactone is a potassium-sparing diuretic that directly antagonizes Aldosterone. Using them concurrently creates a synergistic effect that can lead to life-threatening elevations in serum potassium levels. **2. Why the other options are incorrect:** * **Amiloride:** While Amiloride is also a potassium-sparing diuretic (ENaC inhibitor), the question specifically tests the classic clinical contraindication associated with Aldosterone antagonists in heart failure management. *Note: In clinical practice, both are avoided, but Spironolactone is the high-yield textbook contraindication due to its frequent use in heart failure.* * **Calcium Channel Blockers (CCBs):** ACEIs and CCBs (like Amlodipine) are a common and effective combination for hypertension. ACEIs can actually help reduce the peripheral edema often caused by CCBs. * **Thiazides:** This is a preferred combination. Thiazides cause potassium loss (hypokalemia), which is counterbalanced by the potassium-retaining effect of ACEIs, leading to more stable electrolyte levels. **3. High-Yield Clinical Pearls for NEET-PG:** * **The "Rule of K":** Always monitor potassium when a patient is on ACEIs, ARBs, or Potassium-sparing diuretics. * **Teratogenicity:** ACEIs are strictly contraindicated in pregnancy (cause fetal renal dysgenesis). * **Side Effects:** Remember the mnemonic **CAPTOPRIL** (Cough, Angioedema, Proteinuria, Taste changes, Orthostatic hypotension, Pregnancy contraindication, Renal artery stenosis contraindication, Increased potassium, Leukopenia). * **Bilateral Renal Artery Stenosis:** ACEIs are contraindicated as they can precipitate acute renal failure by reducing efferent arteriolar tone.

Question 806: Which of the following is a beta-blocker antagonist?

A. Glucagon (Correct Answer)
B. Neostigmine
C. Ambenonium
D. All of the above

Explanation: ### Explanation **Correct Option: A. Glucagon** **Mechanism of Action:** Glucagon is considered the **specific antidote** for beta-blocker (BB) overdose. Beta-blockers work by inhibiting the $\beta_1$ receptors, which normally use the Gs-protein pathway to activate **adenylyl cyclase**, increasing intracellular cAMP and resulting in positive inotropic and chronotropic effects. In a BB overdose, this pathway is blocked. Glucagon bypasses the blocked beta-receptors by binding to its own specific **glucagon receptors** on the myocardium. These receptors are also coupled to Gs-proteins, which activate adenylyl cyclase independently of the beta-adrenergic system. This leads to an increase in **cAMP**, restoring heart rate and contractility despite the presence of the antagonist. **Why Incorrect Options are Wrong:** * **B & C (Neostigmine and Ambenonium):** These are **acetylcholinesterase inhibitors** used primarily in the treatment of Myasthenia Gravis. They increase the concentration of acetylcholine at the neuromuscular junction and muscarinic sites. Because they enhance parasympathetic activity, they would actually worsen the bradycardia associated with beta-blocker toxicity rather than reverse it. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice (DOC):** Glucagon is the first-line agent for symptomatic bradycardia and hypotension caused by beta-blocker toxicity. * **Other Treatments:** If glucagon fails, **High-dose Insulin Euglycemic Therapy (HIET)** and IV calcium gluconate are used. * **Side Effects of Glucagon:** High doses can cause significant vomiting; hence, airway protection is vital. * **Mnemonic:** "Glucagon bypasses the block" (it acts via a different receptor to achieve the same result as beta-agonists).

Question 807: Which of the following drugs acts as both an arteriolar and venodilator?

A. Hydralazine
B. Sodium nitroprusside (Correct Answer)
C. Minoxidil
D. Captopril

Explanation: **Explanation:** Sodium Nitroprusside (SNP) is the correct answer because it acts as a **balanced vasodilator**, affecting both resistance vessels (arterioles) and capacitance vessels (veins) [1, 3]. **Mechanism of Action:** SNP is a prodrug that reacts with hemoglobin to release **Nitric Oxide (NO)** [1]. NO activates guanylyl cyclase, increasing intracellular **cGMP**, which leads to dephosphorylation of myosin light chains and subsequent relaxation of smooth muscles in both arteries and veins. * **Arteriolar dilation** reduces Total Peripheral Resistance (Afterload). * **Venodilation** increases venous pooling and reduces venous return (Preload). **Analysis of Incorrect Options:** * **A. Hydralazine:** A direct-acting **pure arteriolar vasodilator** [1, 2]. It has minimal effect on veins, often leading to significant reflex tachycardia. * **C. Minoxidil:** A potent **arteriolar vasodilator** that works by opening ATP-sensitive $K^+$ channels, causing hyperpolarization of smooth muscle cells [1]. It does not affect veins. * **D. Captopril:** While ACE inhibitors do cause both arterial and venous dilation by reducing Angiotensin II and increasing Bradykinin, they are classified primarily as **balanced vasodilators in the context of chronic therapy**. In the specific context of "vasodilator pharmacology" questions, SNP is the classic prototype for immediate, direct-acting balanced dilation. **High-Yield Clinical Pearls for NEET-PG:** 1. **SNP Toxicity:** Prolonged infusion can lead to **Cyanide and Thiocyanate toxicity**. The antidote is **Sodium Thiosulfate** or **Hydroxocobalamin**. 2. **Drug of Choice:** SNP is used in hypertensive emergencies but must be protected from light (it is photosensitive). 3. **Steal Phenomenon:** SNP can cause "Coronary Steal," potentially worsening ischemia in patients with CAD. 4. **Minoxidil Side Effect:** Commonly causes **hypertrichosis** (used topically for alopecia) [1].

Question 808: All of the following statements about the use of spironolactone in CHF are true EXCEPT:

A. It should be administered in low doses to prevent hyperkalemia.
B. It affords prognostic benefit in severe heart failure over and above that afforded by ACE inhibitors.
C. It helps to overcome the refractoriness to thiazides.
D. It affords rapid symptomatic relief in CHF patients. (Correct Answer)

Explanation: ### Explanation **Spironolactone** is a potassium-sparing diuretic and a Mineralocorticoid Receptor Antagonist (MRA). In Chronic Heart Failure (CHF), its primary role is not acute diuresis, but rather long-term neurohormonal modulation. **1. Why Option D is the Correct Answer (The False Statement):** Spironolactone is a **weak diuretic**. It acts on the distal part of the nephron where only a small fraction of sodium is reabsorbed. Unlike loop diuretics (e.g., Furosemide), it does not produce rapid diuresis or immediate symptomatic relief from pulmonary edema. Its benefits in CHF are primarily due to its ability to prevent myocardial fibrosis and remodeling, which takes weeks to months to manifest. **2. Analysis of Other Options:** * **Option A:** Spironolactone carries a significant risk of **hyperkalemia**, especially when combined with ACE inhibitors. Therefore, it is initiated at low doses (e.g., 12.5–25 mg/day) with close monitoring of serum potassium and creatinine. * **Option B:** Large-scale trials like **RALES** have proven that adding low-dose spironolactone to standard therapy (ACE inhibitors + Digoxin) significantly reduces mortality and morbidity in patients with NYHA Class III and IV heart failure. This is known as "Aldosterone Escape" blockade. * **Option C:** In cases of "diuretic resistance," adding spironolactone can help overcome refractoriness to thiazides or loop diuretics by blocking the compensatory distal sodium reabsorption. **Clinical Pearls for NEET-PG:** * **Mechanism:** Competitive antagonist of aldosterone at the Mineralocorticoid Receptor (MR) in the late distal tubule/collecting duct. * **Side Effects:** Hyperkalemia and **Gynecomastia** (due to non-specific binding to androgen and progesterone receptors). **Eplerenone** is a more selective MRA with fewer endocrine side effects. * **Key Trial:** RALES trial (Spironolactone); EMPHASIS-HF trial (Eplerenone).

Question 809: Which of the following is true about dobutamine?

A. Selective beta-1 receptor agonist
B. Increases ventricular filling pressure
C. Half-life is about 2 minutes (Correct Answer)
D. Dopamine receptor agonist

Explanation: ### Explanation **Dobutamine** is a synthetic sympathomimetic amine primarily used in the management of acute heart failure and cardiogenic shock. **1. Why Option C is Correct:** Dobutamine has a very rapid onset of action and a **very short half-life (approximately 2 minutes)**. This occurs because it is rapidly metabolized by COMT (Catechol-O-methyltransferase) and conjugation in the liver. Due to this short duration, it must be administered via continuous intravenous infusion to maintain therapeutic levels, allowing for precise, minute-to-minute titration of cardiac output. **2. Why the Other Options are Incorrect:** * **Option A:** While dobutamine is often simplified as a "selective $\beta_1$ agonist," it is actually a **racemic mixture**. The (+) isomer is a $\beta_1$ agonist and $\alpha_1$ antagonist, while the (-) isomer is an $\alpha_1$ agonist. The net clinical effect is potent **$\beta_1$ stimulation** (inotropic) with mild $\beta_2$ and $\alpha_1$ effects. It is not strictly "selective" in the same way as drugs like Atenolol. * **Option B:** Dobutamine is an **inodilator**. By increasing myocardial contractility and causing mild peripheral vasodilation ($\beta_2$), it improves cardiac emptying and **decreases ventricular filling pressure** (preload) and systemic vascular resistance (afterload). * **Option D:** Unlike dopamine, dobutamine has **no action on dopamine (D) receptors**. It does not promote renal vasodilation through dopaminergic pathways. **3. High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** Dobutamine is the preferred inotrope for **cardiogenic shock** (without severe hypotension) because it increases cardiac output with less tachycardia than isoproterenol. * **Dobutamine Stress Echo:** Used to diagnose ischemic heart disease in patients unable to exercise by increasing myocardial oxygen demand. * **Tachyphylaxis:** Prolonged infusion (over 72 hours) can lead to a decrease in efficacy due to down-regulation of $\beta$-receptors.

Question 810: Which of the following is a Class Ib antiarrhythmic drug?

A. Encainide
B. Flecainide
C. Lidocaine (Correct Answer)
D. Moricizine

Explanation: **Explanation:** The Vaughan-Williams classification categorizes antiarrhythmic drugs based on their primary mechanism of action. **Class I agents** are sodium (Na+) channel blockers that decrease the rate of phase 0 depolarization. They are further subdivided based on their effect on the action potential duration (APD). **1. Why Lidocaine is Correct:** **Lidocaine** is a prototypical **Class Ib** antiarrhythmic. Class Ib agents have low potency for blocking sodium channels and characteristically **shorten the action potential duration (APD)** and effective refractory period (ERP) in ventricular tissue. They bind preferentially to sodium channels in the **inactivated state**, making them highly effective in ischemic tissues (where cells are depolarized). This makes Lidocaine a drug of choice for treating ventricular arrhythmias associated with acute myocardial infarction. **2. Why the Other Options are Incorrect:** * **Encainide and Flecainide (Options A & B):** These belong to **Class Ic**. They are the most potent sodium channel blockers and have a minimal effect on APD. They are used for supraventricular tachycardias but are contraindicated post-MI due to pro-arrhythmic risks (as seen in the CAST trial). * **Moricizine (Option D):** This is a unique Class I agent that shares properties of Classes Ia, Ib, and Ic. However, it is traditionally categorized as a **Class Ic**-like agent or an unclassified Class I drug. **3. NEET-PG High-Yield Pearls:** * **Class Ia (Procainamide, Quinidine, Disopyramide):** Increases APD; can cause QTc prolongation and Torsades de Pointes. * **Class Ib (Lidocaine, Mexiletine):** Decreases APD; "Ischemic tissue specific." * **Class Ic (Flecainide, Propafenone):** No change in APD; "Strongest Na+ channel block." * **Mnemonic for Class I:** "**P**olice **Q**uestion **D**irty **L**ittle **M**en **F**or **E**ating **P**eanuts" (Procainamide, Quinidine, Disopyramide [Ia]; Lidocaine, Mexiletine [Ib]; Flecainide, Encainide, Propafenone [Ic]).

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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