Cardiovascular Drugs — MCQs

Cardiovascular Drugs Indian Medical PG Practice Questions and MCQs

Question 141: Which of the following is not a centrally acting hypertensive agent?

A. Methyldopa
B. Moxonidine
C. Minoxidil (Correct Answer)
D. Clonidine

Explanation: **Explanation:** The question asks to identify the drug that does **not** act via the central nervous system to lower blood pressure. **1. Why Minoxidil is the Correct Answer:** Minoxidil is a **direct-acting peripheral vasodilator**. Its mechanism of action involves opening **ATP-sensitive potassium channels ($K_{ATP}$)** in vascular smooth muscle. This leads to potassium efflux, hyperpolarization, and subsequent relaxation of arterioles (not veins). Because it acts directly on the blood vessels and not the brain, it is not a centrally acting agent. **2. Analysis of Incorrect Options (Centrally Acting Agents):** * **Clonidine:** A prototypical central **$\alpha_2$-adrenergic agonist**. It stimulates $\alpha_2$ receptors in the nucleus tractus solitarius (NTS), decreasing sympathetic outflow from the vasomotor center. * **Methyldopa:** A prodrug converted to $\alpha$-methylnorepinephrine in the brain. It acts as a central **$\alpha_2$ agonist**, making it the drug of choice for hypertension in pregnancy. * **Moxonidine:** A selective **imidazoline $I_1$ receptor agonist** in the rostral ventrolateral medulla. It reduces sympathetic activity with fewer sedative side effects than clonidine. **3. NEET-PG High-Yield Pearls:** * **Minoxidil Side Effects:** Significant reflex tachycardia and salt/water retention (usually co-prescribed with a beta-blocker and diuretic). It also causes **hypertrichosis** (used topically for alopecia). * **Clonidine Withdrawal:** Abrupt cessation leads to a **rebound hypertensive crisis** due to a sudden surge in catecholamines. * **Methyldopa Side Effect:** Can cause a **positive Coombs test** and rare hemolytic anemia.

Question 142: Which of the following conditions precipitates Digoxin toxicity?

A. Hypokalemia (Correct Answer)
B. Hyperkalemia
C. Hypernatremia
D. Hyperphosphatemia

Explanation: **Explanation:**Digoxin works by inhibiting the **Na⁺/K⁺-ATPase pump** on the myocardial cell membrane. Under normal physiological conditions, potassium (K⁺) ions compete with Digoxin for the same binding site on this ATPase pump. In **Hypokalemia (Option A)**, there is less extracellular potassium available to compete for these binding sites. This allows more Digoxin to bind to the pump, leading to excessive inhibition and an exaggerated pharmacological effect, which precipitates **Digoxin toxicity** [2]. Even "normal" therapeutic levels of Digoxin can become toxic in the presence of low potassium. **Analysis of Incorrect Options:** * **Hyperkalemia (Option B):** High potassium levels increase competition for the binding site, effectively reducing Digoxin’s binding and action. While hyperkalemia can *antagonize* Digoxin, it does not precipitate toxicity [1] (though severe toxicity itself can cause hyperkalemia due to pump paralysis). * **Hypernatremia (Option C) & Hyperphosphatemia (Option D):** Sodium and phosphate levels do not directly compete with Digoxin at its binding site on the Na⁺/K⁺-ATPase pump and are not primary triggers for toxicity. **High-Yield Clinical Pearls for NEET-PG:** * **Electrolyte Triad of Toxicity:** Digoxin toxicity is precipitated by **Hypokalemia, Hypomagnesemia, and Hypercalcemia** ("Hi-Cal, Low-Mag, Low-K") [2]. * **ECG Changes:** The most common initial sign of toxicity is **PVCs** (Premature Ventricular Contractions). The most characteristic arrhythmia is **Atrial Tachycardia with AV block**. * **Visual Disturbance:** Patients may report **Xanthopsia** (yellow-green halos around lights). * **Antidote:** Digoxin-specific antibody fragments (**DigiFab**).

Question 143: Which of the following drugs is associated with the highest cardiac mortality?

A. Rofecoxib (Correct Answer)
B. Nicorandil
C. Losartan
D. Metoprolol

Explanation: **Explanation:** **Rofecoxib (Option A)** is the correct answer because it was voluntarily withdrawn from the global market (2004) due to a significantly increased risk of **cardiovascular events**, specifically myocardial infarction and stroke. The underlying medical concept involves the **imbalance of Prostaglandins**. Rofecoxib is a highly selective **COX-2 inhibitor**. While COX-2 inhibition reduces inflammatory Prostaglandin I2 (Prostacyclin) in the vascular endothelium—which is a potent vasodilator and inhibitor of platelet aggregation—it does **not** inhibit COX-1 in platelets. This leaves the production of **Thromboxane A2 (TXA2)**—a potent vasoconstrictor and platelet aggregator—unopposed. This pro-thrombotic state leads to increased cardiac mortality. **Analysis of Incorrect Options:** * **Nicorandil (Option B):** A potassium channel opener used in angina; it is generally cardioprotective and does not increase mortality. * **Losartan (Option C):** An Angiotensin Receptor Blocker (ARB) that **decreases** cardiac mortality and morbidity, especially in patients with hypertension, heart failure, and diabetic nephropathy. * **Metoprolol (Option D):** A cardioselective beta-blocker proven to **reduce** mortality in patients post-myocardial infarction and in chronic heart failure. **High-Yield Clinical Pearls for NEET-PG:** * **VIGOR Trial:** The landmark study that identified the increased CV risk of Rofecoxib compared to Naproxen. * **COX-2 Selectivity:** Celecoxib and Etoricoxib are other members of this class; they are used with extreme caution in patients with pre-existing ischemic heart disease. * **Aspirin Paradox:** Unlike non-selective NSAIDs (like Ibuprofen), COX-2 inhibitors do not interfere with the antiplatelet effect of low-dose Aspirin, but their intrinsic pro-thrombotic risk remains a concern.

Question 144: All of the following statements are true about quinidine except?

A. It blocks myocardial Na+ channels primarily in the open state.
B. It has no effect on myocardial K+ channels. (Correct Answer)
C. It produces frequency dependent blockade of myocardial Na+ channels.
D. It delays recovery of myocardial Na+ channels.

Explanation: Explanation: Quinidine is a prototype Class IA antiarrhythmic drug. To answer this question, one must understand the "Vaughan-Williams classification" and the specific electrophysiological properties of Class IA agents [2]. 1. Why Option B is the correct answer (The False Statement): Contrary to the statement, Quinidine does block myocardial K+ channels (specifically the delayed rectifier current, $I_{Kr}$) [1]. By blocking potassium channels, it prolongs the action potential duration (APD) and the effective refractory period (ERP). This K+ channel blockade is also responsible for the side effect of QT interval prolongation, which can predispose patients to Torsades de Pointes [3]. 2. Analysis of Incorrect Options (True Statements): * Option A & C: Quinidine is a sodium (Na+) channel blocker [1]. It shows "state-dependency," meaning it binds preferentially to channels in the open or activated state. Because it binds more effectively when channels are firing frequently, it exhibits "frequency-dependent" (or use-dependent) blockade, making it more effective in tachyarrhythmias [2]. * Option D: Class IA drugs are characterized by intermediate dissociation kinetics. They delay the recovery of Na+ channels from the inactivated state, thereby increasing the threshold for excitability. High-Yield Clinical Pearls for NEET-PG: * Cinchonism: A classic side effect triad of tinnitus, headache, and dizziness [1]. * Vagolytic Effect: Quinidine has atropine-like (antimuscarinic) properties, which can paradoxically increase AV conduction. * Drug Interaction: Quinidine reduces the renal clearance of Digoxin, leading to digoxin toxicity. * ECG Changes: Widened QRS (Na+ block) and prolonged QT (K+ block).

Question 145: Which of the following drugs does NOT cause dilated cardiomyopathy?

A. Daunorubicin
B. Trastuzumab
C. Doxorubicin
D. Sacubitril (Correct Answer)

Explanation: **Explanation:** The correct answer is **Sacubitril**. **Why Sacubitril is the correct answer:** Sacubitril is a **Neprilysin inhibitor**. It prevents the degradation of natriuretic peptides (ANP, BNP), leading to vasodilation, natriuresis, and inhibition of cardiac remodeling. Far from causing cardiomyopathy, Sacubitril (combined with Valsartan as ARNI) is a **cornerstone therapy used to treat** Heart Failure with Reduced Ejection Fraction (HFrEF) because it improves cardiac function and reduces mortality. **Why the other options are incorrect:** * **Doxorubicin & Daunorubicin (Anthracyclines):** These are classic causes of **Type I Chemotherapy-Induced Cardiotoxicity**. They generate reactive oxygen species (ROS) that cause irreversible myocyte damage and replacement fibrosis, leading to dose-dependent dilated cardiomyopathy. * **Trastuzumab:** This monoclonal antibody (anti-HER2) causes **Type II Cardiotoxicity**. Unlike anthracyclines, it leads to a reversible decrease in myocardial contractility (stunning) without structural damage, but it still manifests clinically as dilated cardiomyopathy/heart failure. **High-Yield Clinical Pearls for NEET-PG:** 1. **Anthracycline Toxicity:** Characterized by "biopsy-proven" myofibrillar loss. Risk is minimized by using **Dexrazoxane** (an iron chelator). 2. **Trastuzumab Toxicity:** Not dose-dependent and usually reversible upon discontinuation. 3. **ARNI (Sacubitril/Valsartan):** Requires a **36-hour washout period** when switching from an ACE inhibitor to prevent the risk of angioedema. 4. **Other drugs causing Dilated Cardiomyopathy:** Alcohol (most common toxin), Cocaine, Chloroquine, and Cyclophosphamide.

Question 146: Postural hypotension and failure of ejaculation is most commonly seen in treatment with?

A. Guanethedine (Correct Answer)
B. Minoxidil
C. Propranolol
D. Sodium nitroprusside

Explanation: **Explanation:** **Guanethidine** is the correct answer because it is an **adrenergic neuron blocker**. It works by inhibiting the release of norepinephrine from postganglionic sympathetic nerve endings and displacing stored norepinephrine, leading to a gradual depletion of catecholamines [1]. 1. **Postural Hypotension:** By blocking the sympathetic outflow, Guanethidine prevents the compensatory vasoconstriction required when a person stands up, leading to a significant drop in blood pressure [1], [2]. 2. **Failure of Ejaculation:** Ejaculation is a sympathetic-mediated process ("S" for Sympathetic = Shoot). Guanethidine’s blockade of peripheral sympathetic nerves prevents the contraction of the vas deferens and seminal vesicles, leading to ejaculatory failure. **Analysis of Incorrect Options:** * **Minoxidil:** A potent direct-acting vasodilator (K+ channel opener). It typically causes reflex tachycardia and fluid retention, not postural hypotension or ejaculatory issues. * **Propranolol:** A non-selective beta-blocker. While it can cause erectile dysfunction (impotence), it does not typically cause failure of ejaculation or significant postural hypotension (as alpha-receptors remain intact for vasoconstriction). * **Sodium Nitroprusside:** A balanced vasodilator (arteriolar and venous) used in hypertensive emergencies. While it can cause a rapid drop in BP, it is administered IV in a controlled setting and is not associated with chronic ejaculatory failure. **High-Yield Clinical Pearls for NEET-PG:** * **"Triple Action" of Guanethidine:** It inhibits release, inhibits reuptake (Uptake-1), and depletes stores of NE [1]. * **Drug Interaction:** Tricyclic Antidepressants (TCAs) and Cocaine block the uptake of Guanethidine into the neuron, reversing its antihypertensive effect [1]. * **Mnemonic:** Sympathetic = **S**hoot (Ejaculation); Parasympathetic = **P**oint (Erection). Guanethidine affects the "Shoot."

Question 147: Which one of the following antihypertensive drugs is contraindicated in pregnancy?

A. Alpha methyldopa
B. Hydralazine
C. Nifedipine
D. Furosemide (Correct Answer)

Explanation: ### Explanation **Correct Option: D. Furosemide** **Why Furosemide is Contraindicated:** Furosemide is a potent loop diuretic. In pregnancy, it is generally avoided because it can cause **placental hypoperfusion**. Diuretics reduce maternal plasma volume, which may interfere with the physiological volume expansion necessary for a healthy pregnancy. This can lead to decreased uterine blood flow, potentially causing fetal growth restriction or neonatal complications. Additionally, it crosses the placental barrier and can cause electrolyte imbalances in the fetus. **Analysis of Incorrect Options:** * **A. Alpha-methyldopa:** This is a centrally acting alpha-2 agonist and has traditionally been the **drug of choice (DOC)** for chronic hypertension in pregnancy due to its long-term safety profile for both mother and fetus. * **B. Hydralazine:** A direct vasodilator used primarily in the management of **acute hypertensive emergencies** in pregnancy (e.g., severe pre-eclampsia). It is considered safe for rapid blood pressure reduction. * **C. Nifedipine:** A calcium channel blocker (dihydropyridine) that is frequently used as a first-line oral agent for maintenance therapy and as a tocolytic to delay preterm labor. **High-Yield NEET-PG Pearls:** 1. **Absolute Contraindications:** ACE inhibitors (e.g., Enalapril) and ARBs (e.g., Losartan) are strictly contraindicated due to **teratogenicity** (renal dysgenesis, skull hypoplasia, and oligohydramnios). Direct Renin Inhibitors (Aliskiren) and Statins are also contraindicated. 2. **Safe Antihypertensives (Mnemonic: Better Mother Love Next-generation):** **B**eta-blockers (Labetalol), **M**ethyldopa, **L**abetalol (often DOC now), **N**ifedipine. 3. **Labetalol** is currently preferred over Methyldopa in many guidelines due to a faster onset and fewer side effects (like sedation).

Question 148: Which of the following is an active metabolite of another drug and is available as a separate drug for the treatment of angina?

A. Isosorbide mononitrate (Correct Answer)
B. Isosorbide dinitrate
C. Nitroglycerine
D. Propranolol

Explanation: **Explanation:** The correct answer is **Isosorbide mononitrate (ISMN)**. **1. Why Isosorbide mononitrate is correct:** Isosorbide dinitrate (ISDN) undergoes extensive first-pass metabolism in the liver, where it is converted into two active metabolites: **Isosorbide-2-mononitrate** and **Isosorbide-5-mononitrate**. Among these, Isosorbide-5-mononitrate is the major metabolite. It has been developed as a separate drug because it possesses **100% oral bioavailability** (unlike the parent drug ISDN) and a longer half-life, making it highly effective for the chronic prophylaxis of angina pectoris. **2. Why other options are incorrect:** * **Isosorbide dinitrate (ISDN):** This is the parent prodrug. While effective, it has low oral bioavailability (~20-25%) due to significant hepatic metabolism. * **Nitroglycerine (Glyceryl Trinitrate):** This is a parent drug, not a metabolite of another anti-anginal. It undergoes near-total first-pass metabolism, which is why it is typically administered sublingually for acute attacks. * **Propranolol:** This is a non-selective beta-blocker. While used in chronic angina to reduce myocardial oxygen demand, it is a parent drug and its active metabolite (4-hydroxypropranolol) is not marketed as a separate anti-anginal agent. **High-Yield Clinical Pearls for NEET-PG:** * **Bioavailability:** ISMN is the only organic nitrate that does not undergo significant first-pass metabolism (Bioavailability ≈ 100%). * **Nitrate Tolerance:** To prevent tolerance, a "nitrate-free interval" of 8–12 hours (usually at night) is mandatory. * **Drug Interaction:** Nitrates are strictly contraindicated with **Sildenafil** (PDE-5 inhibitors) due to the risk of severe, fatal hypotension. * **Monday Disease:** Chronic exposure to nitrates in ammunition factories leads to tolerance; loss of this tolerance over the weekend results in "Monday morning headaches" due to sudden vasodilation.

Question 149: Which drug exhibits a first-dose effect?

A. Yohimbine
B. Verapamil
C. Dopamine
D. Prazosin (Correct Answer)

Explanation: **Explanation:** **Prazosin** is the correct answer because it is a highly selective **alpha-1 (α1) adrenergic blocker**. The "first-dose effect" is a classic pharmacological phenomenon associated with this class. It refers to a sudden, severe episode of **orthostatic hypotension** and syncope occurring within 30–90 minutes of the initial dose. This happens because α1-blockade causes profound peripheral vasodilation (venous and arterial), leading to a rapid drop in venous return and blood pressure. **Analysis of Incorrect Options:** * **A. Yohimbine:** This is a selective **alpha-2 (α2) blocker**. It increases sympathetic outflow and is more likely to cause hypertension and tachycardia rather than a hypotensive first-dose effect. * **B. Verapamil:** A non-dihydropyridine **Calcium Channel Blocker (CCB)**. While it causes vasodilation and hypotension, it does not typically exhibit the acute, dramatic first-dose syncope characteristic of alpha-blockers. * **C. Dopamine:** An **inotropic agent** and catecholamine. It is administered intravenously in acute settings to *increase* blood pressure and cardiac output; it is not associated with first-dose hypotension. **NEET-PG High-Yield Pearls:** * **Management:** To minimize the first-dose effect, patients are advised to take the **first dose at bedtime** ("bedtime dosing") and start with a very low dose (e.g., 1 mg). * **Other Drugs:** This effect is also seen with other selective α1-blockers like **Terazosin** and **Doxazosin**. * **Clinical Use:** Prazosin is used for hypertension and Raynaud’s phenomenon, while Tamsulosin (a subtype-selective α1A blocker) is preferred for Benign Prostatic Hyperplasia (BPH) as it has less effect on blood pressure.

Question 150: Which of the following drugs acts by inhibiting the AT1 subtype of angiotensin receptors?

A. Ramipril
B. Lovastatin
C. Candesartan (Correct Answer)
D. Sumatriptan

Explanation: **Explanation:** The correct answer is **Candesartan**. **Mechanism of Action:** Candesartan belongs to the class of drugs known as **Angiotensin Receptor Blockers (ARBs)**. These drugs act as competitive antagonists at the **AT1 receptor** subtype. By blocking this receptor, ARBs inhibit the harmful effects of Angiotensin II, such as potent vasoconstriction, aldosterone release, sympathetic activation, and cardiac remodeling. Unlike ACE inhibitors, ARBs do not affect bradykinin levels, making them less likely to cause a dry cough. **Analysis of Incorrect Options:** * **A. Ramipril:** This is an **ACE Inhibitor**. It works by inhibiting the Angiotensin-Converting Enzyme, preventing the conversion of Angiotensin I to Angiotensin II. It does not block the receptor itself. * **B. Lovastatin:** This is an **HMG-CoA Reductase Inhibitor** used to treat hyperlipidemia. It inhibits the rate-limiting step in cholesterol synthesis in the liver. * **D. Sumatriptan:** This is a **5-HT$_{1B/1D}$ receptor agonist** used in the acute management of migraine. It causes cranial vasoconstriction and inhibits neurogenic inflammation. **High-Yield NEET-PG Pearls:** * **Suffix Clue:** Drugs ending in **"-sartan"** (e.g., Losartan, Valsartan, Telmisartan) are ARBs. * **Clinical Choice:** ARBs are the preferred alternative for patients who develop a **dry cough** while taking ACE inhibitors. * **Teratogenicity:** Both ACE inhibitors and ARBs are **contraindicated in pregnancy** due to the risk of fetal renal dysgenesis (fetopathy). * **Telmisartan** is unique among ARBs as it also acts as a partial agonist at **PPAR-γ** receptors, potentially improving insulin sensitivity.

Practice by Chapter

Antihypertensive Agents

Practice Questions

Drugs for Heart Failure

Practice Questions

Antiarrhythmic Drugs

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Antianginal Agents

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Lipid-Lowering Drugs

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Anticoagulants and Antiplatelet Drugs

Practice Questions

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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