Cardiovascular Drugs Practice Questions

Q: Which of the following is a selective myosin activator?

Omecamtiv Mecarbil. **Explanation:** **Omecamtiv Mecarbil** is a novel **selective cardiac myosin activator** (cardiac inotrope) [1]. Unlike traditional inotropes, it does not increase intracellular calcium or cAMP. Instead, it binds directly to the catalytic domain of cardiac myosin, accelerating the rate-limiting step of the cross-bridge cycle (transition from the weak-binding to the strong-binding state). This increases the number of myosin heads bound to actin during systole, thereby increasing the **force of contraction** and **systolic ejection period** without increasing myocardial oxygen consumption or heart rate. **Analysis of Incorrect Options:** * **A. Istaroxime:** This is a dual-action investigational drug that inhibits Na+/K+ ATPase (like Digoxin) and activates the SERCA2a pump. It increases calcium sequestration but is not a direct myosin activator. * **C. Tolvaptan:** This is a selective **Vasopressin V2 receptor antagonist** (Aquaretic) used in the management of hyponatremia and autosomal dominant polycystic kidney disease (ADPKD) [1]. * **D. Levosimendan:** This is a **Calcium Sensitizer** [1]. It binds to Troponin C, increasing the sensitivity of the contractile apparatus to existing calcium. It also acts as a K+ channel opener, causing vasodilation (Inodilator). **High-Yield Clinical Pearls for NEET-PG:** * **Omecamtiv Mecarbil** is specifically used in Heart Failure with Reduced Ejection Fraction (HFrEF) [1]. * **Key Advantage:** It improves cardiac function without the pro-arrhythmic risks associated with drugs that increase intracellular calcium (like Dobutamine or Milrinone). * **Mechanism Mnemonic:** "Omecamtiv **M**ecarbil **M**oves **M**yosin."

Q: A patient presents to the medicine emergency with severe CHF. A drug is chosen which is a short-term ionotropic agent with selective adrenergic agonistic activity but lacking dopaminergic agonistic activity. What can this drug be?

Dobutamine. **Explanation:** The patient is presenting with severe Congestive Heart Failure (CHF), requiring an inotropic agent to improve cardiac output. **Why Dobutamine is correct:** Dobutamine is a synthetic catecholamine that acts as a **selective $\beta_1$-adrenergic agonist**. It increases myocardial contractility (positive inotropy) with a relatively lesser effect on heart rate (chronotropy). Crucially, unlike dopamine, it has **no action on dopaminergic ($D_1, D_2$) receptors**. It is the drug of choice for short-term management of cardiac decompensation post-surgery or in CHF/cardiogenic shock. **Why other options are incorrect:** * **Dopamine:** While it is an inotrope, it acts on **dopaminergic receptors** (causing renal vasodilation at low doses) as well as $\beta_1$ and $\alpha_1$ receptors. The question specifically excludes dopaminergic activity. * **Amrinone (Inamrinone):** This is a **Phosphodiesterase-3 (PDE3) inhibitor**, not an adrenergic agonist. It increases cAMP levels to exert inotropic effects but works via a different mechanism than the one described. * **Salmeterol:** This is a long-acting **$\beta_2$-selective agonist** used primarily as a bronchodilator in asthma/COPD; it is not used as an inotropic agent in acute CHF. **High-Yield Clinical Pearls for NEET-PG:** * **Dobutamine** is often preferred over Dopamine in cardiogenic shock because it reduces afterload (slight $\beta_2$ effect) and has a lower tendency to cause tachycardia. * **Isoprenaline** is a non-selective $\beta$-agonist ($\beta_1 = \beta_2$), whereas Dobutamine is $\beta_1$ selective. * **Tolerance:** Tachyphylaxis (decreased response) can occur with Dobutamine if used continuously for more than 72 hours due to receptor down-regulation.

Q: A SLE-like syndrome is most commonly associated with the administration of which of the following drugs?

Procainamide. **Explanation:** **Drug-Induced Lupus Erythematosus (DILE)** is a clinical syndrome that mimics Systemic Lupus Erythematosus (SLE) but occurs as a side effect of certain medications. **Why Procainamide is correct:** Procainamide (a Class IA antiarrhythmic) has the highest risk of inducing DILE, with nearly 20-30% of patients developing symptoms and up to 80% developing antinuclear antibodies (ANA) during long-term therapy. The mechanism involves the drug being metabolized by **N-acetyltransferase**. "Slow acetylators" are at a significantly higher risk because the drug remains in the body longer, leading to the formation of reactive metabolites that trigger an autoimmune response. **Why the other options are incorrect:** * **Rifampicin:** This is an antitubercular drug known for causing orange-colored secretions and hepatotoxicity, but it is not associated with SLE-like syndrome. (Note: Isoniazid, another TB drug, *is* a common cause). * **Digitalis (Digoxin):** Used in heart failure and atrial fibrillation, its toxicity presents with gastrointestinal symptoms, xanthopsia (yellow-green vision), and arrhythmias, not autoimmune syndromes. * **Phenytoin:** While phenytoin can cause various skin reactions (like SJS/TEN) and lymphadenopathy, it is a very rare cause of DILE compared to Procainamide. **NEET-PG High-Yield Pearls:** 1. **Classic Triad of DILE Drugs:** **H**ydralazine, **I**soniazid, **P**rocainamide (**HIP**). 2. **Diagnostic Marker:** **Anti-histone antibodies** are present in >95% of DILE cases (highly specific), while Anti-dsDNA (common in idiopathic SLE) is usually absent. 3. **Clinical Feature:** Unlike idiopathic SLE, DILE rarely involves the CNS or Kidneys. 4. **Management:** Symptoms typically resolve upon discontinuation of the offending drug.

Q: A 70-year-old female presents to the emergency department with chest pain. Her ECG shows ventricular tachycardia with ST-segment elevation, and troponin levels are elevated, leading to a diagnosis of STEMI. What is the initial treatment for the arrhythmia?

Lidocaine. ### Explanation **Correct Option: A. Lidocaine** In the setting of an acute myocardial infarction (STEMI), the myocardium becomes ischemic and acidic. **Lidocaine**, a Class IB antiarrhythmic, is the drug of choice for ventricular arrhythmias associated with acute MI. * **Mechanism:** It selectively binds to sodium channels in the **inactivated state**. Ischemic tissue stays depolarized longer, keeping channels in the inactivated state, which allows Lidocaine to preferentially block sodium entry in damaged cells while sparing healthy tissue. * **Key Concept:** It has little effect on normal conduction but effectively suppresses automaticity in ischemic ventricular fibers. **Why other options are incorrect:** * **B. Adenosine:** This is the drug of choice for Paroxysmal Supraventricular Tachycardia (PSVT). It acts on the AV node and is ineffective for ventricular arrhythmias. * **C. Quinidine:** A Class IA antiarrhythmic. It is contraindicated in MI because it can prolong the QT interval, potentially leading to Torsades de Pointes, and has significant anticholinergic side effects. * **D. Verapamil:** A Calcium Channel Blocker (Class IV). It is used for rate control in atrial arrhythmias (like AFib) but is contraindicated in ventricular tachycardia as it can precipitate severe hypotension and cardiovascular collapse. **NEET-PG High-Yield Pearls:** * **Class IB (Lidocaine, Mexiletine):** "IB is Best post-MI." They have the shortest recovery time from channel binding. * **Route:** Lidocaine must be given **IV** due to extensive first-pass metabolism. * **Toxicity:** Overdose primarily affects the CNS (seizures, tremors, slurred speech). * **Current ACLS Guidelines:** While Amiodarone is now often used first-line for stable VT, Lidocaine remains the classic pharmacological answer for **ischemia-induced** ventricular arrhythmias in exam scenarios.

Q: Which drug directly stimulates contraction of cardiac muscle?

Digitalis. **Explanation:** **1. Why Digitalis is Correct:** Digitalis (Digoxin) is a **positive inotropic agent**. Its primary mechanism involves the inhibition of the **Na⁺/K⁺-ATPase pump** on the cardiac myocyte membrane. This leads to an increase in intracellular sodium, which subsequently slows down the Na⁺/Ca²⁺ exchanger. The resulting increase in intracellular calcium levels allows for more calcium to be available for the contractile apparatus (actin-myosin interaction) during systole, thereby **directly stimulating cardiac muscle contraction**. **2. Why Other Options are Incorrect:** * **ACE Inhibitors (e.g., Enalapril):** These are vasodilators that reduce afterload and preload by inhibiting the conversion of Angiotensin I to Angiotensin II. They do not have a direct stimulatory effect on myocardial contractility. * **Nesiritide:** This is a recombinant B-type natriuretic peptide (BNP). It acts as a potent vasodilator and diuretic to reduce cardiac filling pressures in acute heart failure but does not stimulate contraction. * **Losartan:** An Angiotensin II Receptor Blocker (ARB) that works by blocking AT1 receptors. Like ACE inhibitors, its benefit in heart failure is through neurohormonal blockade and vasodilation, not direct inotropy. **3. NEET-PG High-Yield Pearls:** * **Electrolyte Interaction:** Hypokalemia increases the risk of Digitalis toxicity because K⁺ and Digoxin compete for the same binding site on the Na⁺/K⁺-ATPase pump. * **ECG Changes:** Digoxin typically causes a "reverse tick" or "hockey stick" appearance (ST-segment depression). * **Therapeutic Use:** It is the drug of choice for controlling ventricular rate in patients with **Atrial Fibrillation** who also have heart failure. * **Antidote:** Digibind (Digoxin-specific Fab fragments).

Q: Which one of the following drugs is contraindicated in acute myocardial infarction?

Pentazocine. **Explanation:** In the management of Acute Myocardial Infarction (AMI), the primary goal is to reduce myocardial oxygen demand and improve coronary perfusion. **Why Pentazocine is Contraindicated:** Pentazocine is an opioid agonist-antagonist. Unlike pure mu-agonists, it has significant **sympathomimetic effects**. It increases systemic vascular resistance (afterload), heart rate, and pulmonary artery pressure. These effects lead to an **increase in myocardial oxygen demand**, which can exacerbate ischemia and extend the size of the infarct. Therefore, it is strictly avoided in AMI. **Analysis of Incorrect Options:** * **Morphine:** This is the drug of choice for pain relief in AMI (especially STEMI). It provides potent analgesia and has beneficial hemodynamic effects, such as venodilation (reducing preload) and reducing sympathetic tone, which lowers myocardial oxygen demand. * **Nitroglycerin (NTG):** A potent vasodilator used to relieve ischemic chest pain. It reduces both preload and afterload, improving coronary blood flow. (Note: It is only contraindicated in right ventricular infarction or if the patient has recently used Sildenafil). * **Beta-blockers:** These are standard therapy in AMI (unless contraindicated by heart failure or bradycardia). They reduce heart rate and contractility, thereby decreasing oxygen consumption and reducing the risk of arrhythmias. **High-Yield Clinical Pearls for NEET-PG:** * **MONA regimen:** The classic mnemonic for AMI management: **M**orphine, **O**xygen, **N**itroglycerin, **A**spirin. * **Pentazocine & the Heart:** Always remember that Pentazocine "stresses" the heart, while Morphine "rests" the heart. * **Morphine Side Effect:** Be cautious of bradycardia and hypotension; the antidote is Naloxone.

Q: Which of the following is a cardioselective beta-blocker?

Metoprolol. **Explanation:** **Beta-blockers** are classified based on their receptor selectivity. **Metoprolol** is a **cardioselective (Beta-1 selective)** blocker. These drugs primarily inhibit $\beta_1$ receptors located in the heart, leading to a decrease in heart rate, contractility, and AV conduction, while having minimal effect on $\beta_2$ receptors in the bronchi and peripheral vasculature at therapeutic doses. **Analysis of Options:** * **Metoprolol (Correct):** It belongs to the second generation of beta-blockers. Other common cardioselective agents include **A**tenolol, **B**isoprolol, **E**smolol, and **N**ebivolol (Mnemonic: **"A-B-E-M-N"**). * **Propranolol & Timolol (Incorrect):** These are **first-generation, non-selective** beta-blockers. They block both $\beta_1$ and $\beta_2$ receptors. Propranolol is highly lipid-soluble (crosses BBB), while Timolol is commonly used topically for glaucoma. * **Carvedilol (Incorrect):** This is a **third-generation, non-selective** beta-blocker that also possesses **alpha-1 ($\alpha_1$) blocking** properties. It is frequently used in chronic heart failure due to its vasodilatory and antioxidant effects. **High-Yield Clinical Pearls for NEET-PG:** 1. **Nebivolol** is the most highly selective $\beta_1$ blocker and also stimulates Nitric Oxide (NO) release, causing vasodilation. 2. **Esmolol** has the shortest half-life (~9 minutes) and is administered IV for acute arrhythmias or aortic dissection. 3. **Cardioselectivity is dose-dependent:** At high doses, even selective blockers like Metoprolol can lose their selectivity and cause bronchoconstriction. 4. **Contraindication:** Non-selective beta-blockers (like Propranolol) are strictly contraindicated in patients with **Asthma/COPD** due to the risk of life-threatening bronchospasm.

Q: All of the following are used in atrial arrhythmia EXCEPT?

Lignocaine. **Explanation:** The correct answer is **Lignocaine (Lidocaine)**. **Why Lignocaine is the correct answer:** Lignocaine is a **Class IB antiarrhythmic** agent. Its primary mechanism involves blocking activated and inactivated voltage-gated sodium channels, specifically in the **ventricular myocardium** and Purkinje fibers. It has a very fast "on-off" dissociation kinetics and a preference for tissues with long action potentials. Because the action potential duration (APD) in the atria is very short, Lignocaine does not have sufficient time to bind to sodium channels in atrial tissue. Consequently, it is **ineffective for atrial arrhythmias** and is used exclusively for ventricular arrhythmias (e.g., post-MI or digitalis-induced ventricular tachycardia). **Analysis of incorrect options:** * **Digoxin:** A cardiac glycoside that increases vagal tone, slowing conduction through the AV node. It is used for rate control in atrial fibrillation and flutter. * **Verapamil:** A Class IV antiarrhythmic (Calcium Channel Blocker). It slows AV nodal conduction and is a drug of choice for terminating Paroxysmal Supraventricular Tachycardia (PSVT). * **Quinidine:** A Class IA antiarrhythmic. It blocks sodium channels and has a moderate effect on potassium channels, increasing the refractory period in both atria and ventricles. It can be used to maintain sinus rhythm in atrial fibrillation. **High-Yield Clinical Pearls for NEET-PG:** * **Lignocaine** is the drug of choice for **emergency treatment of ventricular arrhythmias** (though Amiodarone is now often preferred in ACLS protocols). * **Side Effects of Lignocaine:** Primarily neurological (seizures, tremors, blurred vision) due to its ability to cross the blood-brain barrier. * **Class IB Mnemonic:** "Lidocaine, Mexiletine, Phenytoin" — **"L**earn **M**ore **P**harmacology" (Used for Ventricular arrhythmias only). * **Adenosine** is the drug of choice for acute termination of PSVT.

Question 1

Which of the following is a selective myosin activator?

Accepted Answer

Omecamtiv Mecarbil

Answer

Istaroxime

Answer

Tolvaptan

Answer

Levosimendan

Question 2

Nicotinic acid acts by which of the following mechanisms?

Accepted Answer

Inhibiting the release of free fatty acids from adipose tissue

Answer

Inhibiting HMG-CoA synthatase

Answer

Inhibiting HMG CoA reductase

Answer

Decreasing absorption of cholesterol

Question 3

A patient presents to the medicine emergency with severe CHF. A drug is chosen which is a short-term ionotropic agent with selective adrenergic agonistic activity but lacking dopaminergic agonistic activity. What can this drug be?

Accepted Answer

Dobutamine

Answer

Dopamine

Answer

Amrinone

Answer

Salmeterol

Question 4

A SLE-like syndrome is most commonly associated with the administration of which of the following drugs?

Accepted Answer

Procainamide

Answer

Rifampicin

Answer

Digitalis

Answer

Phenytoin

Question 5

A 70-year-old female presents to the emergency department with chest pain. Her ECG shows ventricular tachycardia with ST-segment elevation, and troponin levels are elevated, leading to a diagnosis of STEMI. What is the initial treatment for the arrhythmia?

Accepted Answer

Lidocaine

Answer

Adenosine

Answer

Quinidine

Answer

Verapamil

Question 6

Which drug directly stimulates contraction of cardiac muscle?

Accepted Answer

Digitalis

Answer

ACE inhibitors

Answer

Nesiritide

Answer

Losartan

Question 7

Which one of the following drugs is contraindicated in acute myocardial infarction?

Accepted Answer

Pentazocine

Answer

Morphine

Answer

Nitroglycerin

Answer

Beta blockers

Question 8

Which drug is not useful in a hypertensive emergency?

Accepted Answer

Indapamide

Answer

IV hydralazine

Answer

Sublingual nifedipine

Answer

Sodium nitroprusside

Question 9

Which of the following is a cardioselective beta-blocker?

Accepted Answer

Metoprolol

Answer

Timolol

Answer

Carvedilol

Answer

Propranolol

Question 10

All of the following are used in atrial arrhythmia EXCEPT?

Accepted Answer

Lignocaine

Answer

Digoxin

Answer

Verapamil

Answer

Quinidine

Cardiovascular Drugs — MCQs

Cardiovascular Drugs — MCQs

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