Cardiovascular Drugs — MCQs

Cardiovascular Drugs Indian Medical PG Practice Questions and MCQs

Question 881: Sublingual nitroglycerin for the treatment of acute chest pain can cause which of the following?

A. Hypotension
B. Headache (Correct Answer)
C. Bradycardia
D. Sexual dysfunction

Explanation: **Explanation:** **Nitroglycerin (GTN)** is a potent vasodilator used primarily for the relief of acute angina. Its mechanism involves the release of nitric oxide (NO), which increases cGMP levels, leading to smooth muscle relaxation. **Why Headache is the Correct Answer:** The most common side effect of sublingual nitroglycerin is **headache**. This occurs because the drug causes significant **vasodilation of meningeal and extracranial arteries**. This rapid expansion of cerebral vessels increases intracranial pressure and stretches pain-sensitive structures, often described by patients as a "throbbing" headache. In clinical practice, this is so common that it is often used as a marker that the drug is potent and active. **Analysis of Incorrect Options:** * **A. Hypotension:** While nitroglycerin *can* cause orthostatic hypotension, it is generally considered a secondary effect or a complication of overdose rather than the most characteristic/frequent side effect associated with the immediate sublingual dose in the context of this question. * **C. Bradycardia:** Nitroglycerin typically causes **reflex tachycardia**, not bradycardia. The drop in blood pressure triggers a compensatory sympathetic response to maintain cardiac output. * **D. Sexual Dysfunction:** This is not an adverse effect of nitrates. However, there is a major contraindication: nitrates should never be taken with Sildenafil (PDE-5 inhibitors) as the combination can cause life-threatening hypotension. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism of Action:** Primarily causes **venodilation**, which decreases preload and reduces myocardial oxygen demand. * **Storage:** GTN is volatile and light-sensitive; it must be stored in dark, tightly sealed glass containers. * **Nitrate Tolerance:** Continuous exposure leads to a loss of effect (depletion of free sulfhydryl groups). A "nitrate-free interval" of 8–12 hours is required daily. * **Monday Disease:** Workers in dynamite factories experienced headaches on Mondays (due to re-exposure) which disappeared by Friday as tolerance developed over the week.

Question 882: Which of the following is a monovalent cation that can reverse a digitalis-induced arrhythmia?

A. Digibind antibodies
B. Lidocaine
C. Magnesium
D. Potassium (Correct Answer)

Explanation: **Explanation:** **Mechanism of the Correct Answer:** Digitalis (Digoxin) works by inhibiting the **Na+/K+-ATPase pump**. In toxicity, excessive inhibition leads to intracellular potassium depletion and extracellular hyperkalemia (in acute cases). However, **Potassium (Option D)** is the specific **monovalent cation** used to reverse arrhythmias. Potassium acts by: 1. **Competitive Inhibition:** It competes with digoxin for binding sites on the Na+/K+-ATPase pump. Increasing extracellular potassium promotes the dissociation of digoxin from the enzyme. 2. **Electrophysiology:** It decreases abnormal automaticity in the Purkinje fibers, which is the primary cause of digitalis-induced tachyarrhythmias. **Analysis of Incorrect Options:** * **A. Digibind antibodies:** While these are the definitive treatment for life-threatening digoxin toxicity, they are **proteins (Fab fragments)**, not monovalent cations. * **B. Lidocaine:** This is the drug of choice for digitalis-induced ventricular arrhythmias, but it is a **local anesthetic/Class IB antiarrhythmic**, not a cation. * **C. Magnesium:** This is a **divalent cation** ($Mg^{2+}$). It is highly effective in treating digitalis-induced arrhythmias (especially if hypomagnesemia is present), but it does not fit the "monovalent" criteria. **High-Yield Clinical Pearls for NEET-PG:** * **Hypokalemia** predisposes to digoxin toxicity because there is less competition for the pump binding sites. * **Hyperkalemia** is a marker of **acute** severe digitalis poisoning (prognostic indicator). * **Classic ECG sign:** "Reverse Tick" or "Sagging" ST-segment depression (Salvador Dali sign). * **Contraindication:** Never use **Calcium** in digoxin toxicity ("Stone Heart" phenomenon).

Question 883: All of the following are nonselective beta-blockers with additional actions, except?

A. Carvedilol
B. Betoxalol (Correct Answer)
C. Caeolol
D. Labetalol

Explanation: **Explanation** The question tests the classification of beta-blockers based on their receptor selectivity and additional pharmacological properties (Vasodilatory or Pleiotropic effects). **1. Why Betaxolol is the correct answer:** Betaxolol is a **highly selective $\beta_1$-blocker** (second generation). It does not belong to the nonselective category. While it is used topically in glaucoma due to its membrane-stabilizing activity, it lacks the significant "additional" vasodilatory actions (like $\alpha$-blockade or nitric oxide release) characteristic of the third-generation beta-blockers listed in the other options. **2. Analysis of Incorrect Options:** * **Carvedilol:** A nonselective $\beta$-blocker with **$\alpha_1$-blocking** activity. It also possesses antioxidant and calcium-channel blocking properties, making it a mainstay in chronic heart failure management. * **Carteolol:** A nonselective $\beta$-blocker with **Intrinsic Sympathomimetic Activity (ISA)**. It is unique because it also acts as a $\beta_2$-agonist, which helps in reducing intraocular pressure while potentially causing less bradycardia. * **Labetalol:** A nonselective $\beta$-blocker with additional **$\alpha_1$-blocking** activity (ratio of $\alpha:\beta$ is 1:3 for oral and 1:7 for IV). It is a drug of choice for hypertensive emergencies and pregnancy-induced hypertension. **Clinical Pearls for NEET-PG:** * **Third-generation Vasodilatory Beta-blockers:** * *Nonselective:* Labetalol, Carvedilol, Carteolol, Bucindolol. * *$\beta_1$ Selective:* Nebivolol (via NO release), Celiprolol, Betaxolol (minimal). * **Nebivolol** is the most $\beta_1$-selective blocker currently available. * **Esmolol** is the shortest-acting $\beta$-blocker (half-life ~9 mins) due to metabolism by RBC esterases. * **Sotalol** is a nonselective $\beta$-blocker that also acts as a Class III antiarrhythmic (K+ channel blocker).

Question 884: Which of the following is a L-type calcium channel blocker?

A. Nifedipine
B. Amlodipine
C. Diltiazem
D. All of the above (Correct Answer)

Explanation: **Explanation:** Calcium Channel Blockers (CCBs) are a heterogeneous group of drugs that primarily act by blocking the **L-type (Long-lasting)** voltage-gated calcium channels. These channels are predominantly found in the myocardium, cardiac conduction tissue, and vascular smooth muscle. By inhibiting the entry of calcium ions, these drugs cause vasodilation and decrease cardiac contractility/conduction. **Why "All of the above" is correct:** L-type CCBs are chemically classified into three distinct categories, all of which are represented in the options: * **Dihydropyridines (DHPs):** These are primarily potent peripheral vasodilators. Both **Nifedipine** (short-acting) and **Amlodipine** (long-acting) belong to this class. * **Benzothiazepines:** **Diltiazem** is the prototype of this class, possessing intermediate effects (both vasodilator and cardiodepressant). * **Phenylalkylamines:** Verapamil (not listed) belongs here and is the most cardioselective. Since Nifedipine, Amlodipine, and Diltiazem all exert their primary pharmacological effect by blocking the L-type calcium channel, Option D is the correct answer. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** Amlodipine is a first-line agent for Hypertension. * **Nifedipine:** Short-acting formulations are avoided in HTN emergencies due to the risk of reflex tachycardia and MI; however, it is the CCB of choice in **Pregnancy-Induced Hypertension (PIH)**. * **Verapamil/Diltiazem:** These are used as Rate Control agents in Atrial Fibrillation but are **contraindicated in Heart Failure** (due to negative inotropic effects) and WPW syndrome. * **Side Effects:** Peripheral edema (most common with DHPs), gingival hyperplasia, and constipation (especially with Verapamil).

Question 885: Ranolazine is a?

A. Vasodilator
B. Antianginal (Correct Answer)
C. Antihypertensive
D. Antiarrhythmic

Explanation: **Explanation:** **Ranolazine** is a novel **antianginal** drug used primarily for the management of chronic stable angina. It is often used as a second-line agent or in combination with beta-blockers when symptoms are not adequately controlled. **Mechanism of Action:** The core mechanism involves the **selective inhibition of the late inward sodium current ($I_{Na}$)** in myocardial cells. During ischemia, there is an excess of late sodium entry, which leads to an intracellular calcium overload via the sodium-calcium exchanger. By blocking this sodium current, Ranolazine reduces calcium overload, improves myocardial relaxation (diastolic function), and decreases ventricular wall tension, thereby reducing oxygen demand **without** significantly affecting heart rate or blood pressure. **Analysis of Incorrect Options:** * **A. Vasodilator:** Unlike nitrates or calcium channel blockers, Ranolazine does not cause significant peripheral or coronary vasodilation. * **C. Antihypertensive:** Ranolazine has a negligible effect on systemic blood pressure and is not indicated for hypertension. * **D. Antiarrhythmic:** While it can prolong the QT interval (a property of Class III antiarrhythmics), it is not classified or clinically used as an antiarrhythmic agent. **High-Yield Clinical Pearls for NEET-PG:** * **Metabolism:** It is metabolized by **CYP3A4**; therefore, it is contraindicated with potent inhibitors like ketoconazole or clarithromycin. * **ECG Change:** It causes **QT interval prolongation**, but paradoxically, it carries a low risk of Torsades de Pointes. * **Metabolic Effect:** It can slightly reduce **HbA1c** levels, making it a favorable choice in diabetic patients with angina. * **Hemodynamics:** It is unique because it provides anti-ischemic benefits without decreasing heart rate or blood pressure (useful in patients with low baseline BP/HR).

Question 886: Beta-blockers are used in all of the following conditions EXCEPT?

A. Hypertension
B. Thyrotoxicosis
C. Variant angina (Correct Answer)
D. All of the above

Explanation: **Explanation:** The correct answer is **Variant Angina (Prinzmetal Angina)**. **1. Why Beta-blockers are contraindicated in Variant Angina:** Variant angina is caused by **coronary artery vasospasm** rather than atherosclerosis. Beta-blockers inhibit $\beta_2$ receptors, which are responsible for vasodilation. When these receptors are blocked, the $\alpha_1$ receptors (which cause vasoconstriction) are left **unopposed**. This can lead to worsening of the coronary spasm, potentially triggering a myocardial infarction. The drugs of choice for Variant Angina are Calcium Channel Blockers (CCBs) and Nitrates. **2. Why other options are incorrect:** * **Hypertension:** Beta-blockers (like Atenolol or Metoprolol) are standard antihypertensive agents. they reduce blood pressure by decreasing cardiac output and inhibiting renin release from the kidneys. * **Thyrotoxicosis:** Beta-blockers (specifically **Propranolol**) are used to manage the "thyroid storm" or symptomatic hyperthyroidism. They control tachycardia, tremors, and anxiety, and Propranolol specifically inhibits the peripheral conversion of $T_4$ to the more active $T_3$. **Clinical Pearls for NEET-PG:** * **Non-selective Beta-blockers** (e.g., Propranolol) are contraindicated in **Asthma/COPD** due to $\beta_2$ blockade causing bronchospasm. * **Cardioselective Beta-blockers** (A-M: Atenolol, Bisoprolol, Metoprolol) act primarily on $\beta_1$ receptors and are safer in respiratory patients. * **Labetalol** is the drug of choice for hypertension in pregnancy. * **Esmolol** is the shortest-acting beta-blocker, administered IV for hypertensive emergencies or intraoperative tachycardia.

Question 887: Which statin has the maximum oral bioavailability?

A. Fluvastatin (Correct Answer)
B. Atorvastatin
C. Pravastatin
D. Simvastatin

Explanation: **Explanation:** Statins (HMG-CoA reductase inhibitors) vary significantly in their pharmacokinetic profiles, particularly regarding solubility and bioavailability. **Fluvastatin** has the highest oral bioavailability among all statins, reaching approximately **24% to 30%**. While most statins undergo extensive first-pass metabolism in the liver, Fluvastatin’s relatively higher systemic availability distinguishes it from others in this class. **Analysis of Options:** * **Fluvastatin (Correct):** It is a synthetic, hydrophilic statin with the highest bioavailability (~30%). It is rapidly and completely absorbed, though it still undergoes some first-pass extraction. * **Atorvastatin (Incorrect):** While it is a very potent and commonly used statin, its oral bioavailability is only about **12%** due to extensive first-pass metabolism. * **Pravastatin (Incorrect):** This is a hydrophilic statin with a bioavailability of approximately **17%**. * **Simvastatin (Incorrect):** It is a prodrug administered in the inactive lactone form. It is highly lipophilic and undergoes massive first-pass metabolism, resulting in a very low systemic bioavailability of **<5%**. **High-Yield NEET-PG Pearls:** * **Prodrug Statins:** Lovastatin and Simvastatin (all others are active drugs). * **Longest Half-life:** Rosuvastatin (~19 hours) and Atorvastatin (~14 hours). * **Hydrophilic Statins:** Pravastatin and Rosuvastatin (less likely to cross the blood-brain barrier and cause sleep disturbances). * **Metabolism:** Most statins are metabolized by **CYP3A4** (except Pravastatin, Rosuvastatin, and Pitavastatin), making them prone to drug interactions with macrolides or ketoconazole, increasing the risk of **myopathy/rhabdomyolysis**.

Question 888: All of the following drugs act by blocking calcium channels except:

A. Dantrolene (Correct Answer)
B. Nicardipine
C. Diltiazem
D. Verapamil

Explanation: **Explanation:** The core of this question lies in distinguishing between **Voltage-Gated Calcium Channels (VGCC)** found on cell membranes and **Ryanodine Receptors (RyR)** found on the sarcoplasmic reticulum. **1. Why Dantrolene is the correct answer:** Dantrolene does not block membrane calcium channels. Instead, it acts intracellularly by binding to the **Ryanodine Receptor (RyR1)** on the sarcoplasmic reticulum of skeletal muscle. This inhibits the release of calcium into the cytosol, thereby preventing muscle contraction. It is the drug of choice for **Malignant Hyperthermia** and **Neuroleptic Malignant Syndrome**. **2. Why the other options are incorrect:** * **Verapamil & Diltiazem:** These are Non-dihydropyridine Calcium Channel Blockers (CCBs). Verapamil (a Phenylalkylamine) acts primarily on the heart, while Diltiazem (a Benzothiazepine) acts on both the heart and blood vessels. They block **L-type voltage-gated calcium channels**. * **Nicardipine:** This is a Dihydropyridine (DHP) CCB. Like amlodipine and nifedipine, it selectively blocks L-type calcium channels in vascular smooth muscle, leading to vasodilation. **Clinical Pearls for NEET-PG:** * **Mnemonic for CCB classes:** **V**ery **D**iscrete **N**ature (**V**erapamil, **D**iltiazem, **N**ifedipine/Nicardipine). * **Dantrolene Side Effect:** Significant hepatotoxicity (monitor LFTs). * **Drug of Choice:** Verapamil is the DOC for prophylaxis of Cluster Headaches and Paroxysmal Supraventricular Tachycardia (PSVT). * **Nimodipine:** A specific CCB used to prevent vasospasm in Subarachnoid Hemorrhage (SAH).

Question 889: Which of the following antiarrhythmic drugs has the most prominent anticholinergic action?

A. Quinidine
B. Lignocaine
C. Disopyramide (Correct Answer)
D. Procainamide

Explanation: **Explanation:** **Disopyramide** is a Class IA antiarrhythmic drug known for its potent **anticholinergic (atropine-like) effects**. Among all antiarrhythmic agents, it possesses the most significant muscarinic receptor-blocking activity. This leads to classic side effects such as dry mouth, blurred vision, urinary retention (especially in elderly males with BPH), and constipation. Clinically, its vagolytic action can paradoxically increase the heart rate by enhancing AV nodal conduction, which is why it is often co-administered with AV nodal blockers. **Analysis of Other Options:** * **Quinidine (Option A):** While Quinidine also possesses anticholinergic properties, they are significantly **less potent** than those of Disopyramide. Quinidine is more famously associated with "Cinchonism" (tinnitus, headache, dizziness) and alpha-blocking activity (causing hypotension). * **Lignocaine (Option B):** A Class IB agent that works primarily on inactivated sodium channels in ischemic tissues. It has **no anticholinergic activity** and is mainly associated with CNS side effects (seizures, tremors). * **Procainamide (Option C):** A Class IA agent with the **least anticholinergic effect** in its class. Its primary clinical concern is the development of a Reversible Lupus-like syndrome (in slow acetylators). **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** Disopyramide is uniquely used in **Hypertrophic Obstructive Cardiomyopathy (HOCM)** because its negative inotropic effect helps reduce the outflow gradient. * **Contraindication:** Due to its strong anticholinergic profile, it is strictly contraindicated in patients with **Glaucoma** and **Prostatic Hypertrophy**. * **Class IA Mnemonic:** "**P**olice **D**epartment **Q**uarter" (**P**rocainamide, **D**isopyramide, **Q**uinidine). All Class IA drugs increase the APD and QT interval.

Question 890: Amrinone acts by?

A. Inhibiting phosphodiesterase (Correct Answer)
B. ATPase inhibitor
C. Calcium channel blocker
D. IC/ channel opener

Explanation: **Explanation:** **Amrinone** (and its derivative Milrinone) belongs to the class of **Bipyridines**. These drugs act as selective **Phosphodiesterase-3 (PDE-3) inhibitors**. 1. **Mechanism of Action (Why A is correct):** In cardiac myocytes, PDE-3 is responsible for the degradation of cyclic AMP (cAMP). By inhibiting this enzyme, Amrinone increases intracellular cAMP levels. This leads to increased calcium influx during action potentials, resulting in a **positive inotropic effect** (increased contractility). In vascular smooth muscle, the rise in cAMP causes relaxation, leading to **vasodilation** (decreased preload and afterload). Due to this dual action, these drugs are often called **"Inodilators."** 2. **Analysis of Incorrect Options:** * **B. ATPase inhibitor:** This describes **Digoxin** (Cardiac glycosides), which inhibits the Na+/K+-ATPase pump. * **C. Calcium channel blocker:** Drugs like Verapamil or Diltiazem block L-type calcium channels, leading to negative inotropy and vasodilation (the opposite of Amrinone’s cardiac effect). * **D. K+ channel opener:** Drugs like Minoxidil or Nicorandil open potassium channels, primarily causing hyperpolarization and vasodilation, but they do not have direct positive inotropic effects. **High-Yield Clinical Pearls for NEET-PG:** * **Indication:** Short-term management of severe acute heart failure or refractory chronic heart failure. * **Side Effects:** A major limiting side effect of **Amrinone is Thrombocytopenia** (less common with Milrinone). * **Milrinone** is generally preferred over Amrinone due to its higher potency, shorter half-life, and lower risk of bone marrow suppression. * **Note:** Long-term oral use of PDE-3 inhibitors is avoided as it has been shown to increase mortality in heart failure patients.

Practice by Chapter

Antihypertensive Agents

Practice Questions

Drugs for Heart Failure

Practice Questions

Antiarrhythmic Drugs

Practice Questions

Antianginal Agents

Practice Questions

Lipid-Lowering Drugs

Practice Questions

Anticoagulants and Antiplatelet Drugs

Practice Questions

Thrombolytic Agents

Practice Questions

Drugs Used in Pulmonary Hypertension

Practice Questions

Drugs Used in Shock

Practice Questions

Cardiovascular Effects of Non-Cardiovascular Drugs

Practice Questions

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