Cardiovascular Drugs — MCQs

Cardiovascular Drugs Indian Medical PG Practice Questions and MCQs

Question 261: Which antihistamine is associated with an increased risk of cardiac arrhythmias when co-administered with erythromycin or ketoconazole?

A. Diphenhydramine
B. Clemastine
C. Loratadine
D. Terfenadine (Correct Answer)

Explanation: **Explanation:** **Correct Option: D (Terfenadine)** Terfenadine is a second-generation H1-antihistamine that acts as a **pro-drug**. It is normally metabolized by the hepatic cytochrome **CYP3A4** enzyme into its active, non-toxic metabolite, fexofenadine. When co-administered with CYP3A4 inhibitors like **Erythromycin** (macrolide) or **Ketoconazole** (azole antifungal), the metabolism of terfenadine is blocked. This leads to high plasma levels of the parent drug, which blocks the delayed rectifier potassium channels ($I_{Kr}$) in the heart. This action prolongs the QT interval, potentially leading to a life-threatening polymorphic ventricular tachycardia known as **Torsades de Pointes**. Due to this risk, terfenadine was withdrawn from the market and replaced by fexofenadine. **Incorrect Options:** * **A & B (Diphenhydramine & Clemastine):** These are first-generation antihistamines. While they have sedative and anticholinergic side effects, they do not significantly block cardiac potassium channels or interact with CYP3A4 to cause Torsades de Pointes. * **C (Loratadine):** This is a second-generation antihistamine. While it is metabolized by CYP3A4, it does not possess the same potent cardiac potassium channel-blocking activity as terfenadine, making it much safer regarding cardiotoxicity. **High-Yield Clinical Pearls for NEET-PG:** * **Astemizole** is another second-generation antihistamine withdrawn for the same reason (QT prolongation). * **Fexofenadine** is the active metabolite of terfenadine; it is safe because it does not block cardiac $K^+$ channels. * **Mnemonic for QT-prolonging drugs:** "ABCDE" – **A**ntiarrythmics (Class IA, III), **B**iotics (Macrolides, Quinolones), **C**ant Psychotics (Haloperidol), **D**epressants (TCAs), **E**metics (Ondansetron).

Question 262: Which of the following ACE inhibitors has the longest half-life?

A. Enalapril
B. Lisinopril
C. Perindopril (Correct Answer)
D. Ramipril

Explanation: ### Explanation **Correct Option: C. Perindopril** The duration of action of ACE inhibitors is primarily determined by their terminal elimination half-life and their affinity for the ACE enzyme. **Perindopril** is a long-acting ACE inhibitor with a terminal half-life of approximately **30 to 120 hours**. This extended duration is due to its high lipophilicity and strong, persistent binding to the tissue-bound ACE enzyme, making it suitable for once-daily dosing with 24-hour blood pressure control. **Analysis of Incorrect Options:** * **A. Enalapril:** This is a prodrug converted to enalaprilat. Its effective half-life is approximately **11 hours**. While it is commonly used, it has a significantly shorter duration compared to perindopril. * **B. Lisinopril:** Unlike most ACE inhibitors, lisinopril is not a prodrug. It has a half-life of about **12 hours**. It is long-acting but does not reach the terminal half-life levels of perindopril. * **C. Ramipril:** A popular prodrug converted to ramiprilat. It has a half-life of approximately **13–17 hours**. While it provides 24-hour coverage, its pharmacokinetic profile is shorter than that of perindopril. **High-Yield NEET-PG Pearls:** * **Shortest Half-life:** **Captopril** (approx. 2 hours); it is the only ACE inhibitor that usually requires 2–3 doses per day. * **Not Prodrugs:** **Lisinopril and Captopril** are the only two ACE inhibitors that are active as such and do not require hepatic activation. * **Excretion:** Most ACE inhibitors are renally excreted. **Fosinopril and Spirapril** are unique because they have significant biliary excretion, making them safer in patients with renal impairment. * **Adverse Effects:** Remember the mnemonic **CAPTOPRIL** (Cough, Angioedema, Proteinuria/Potassium excess, Taste changes, Orthostatic hypotension, Pregnancy contraindication, Renal artery stenosis contraindication, Increased renin, Leukopenia).

Question 263: Riociguat is used for which condition?

A. Pulmonary hypertension (Correct Answer)
B. Myocarditis
C. Atrial fibrillation
D. Stroke

Explanation: **Explanation:** **Riociguat** is a first-in-class **soluble Guanylate Cyclase (sGC) stimulator**. Its mechanism of action is twofold: it sensitizes sGC to endogenous Nitric Oxide (NO) and directly stimulates the receptor independently of NO. This leads to increased synthesis of cGMP, resulting in potent vasodilation and anti-proliferative effects on the pulmonary vasculature. * **Why Option A is correct:** Riociguat is specifically FDA-approved for **Pulmonary Arterial Hypertension (PAH - Group 1)** and **Chronic Thromboembolic Pulmonary Hypertension (CTEPH - Group 4)**, especially in patients with inoperable or persistent/recurrent disease after surgery. **Why other options are incorrect:** * **B. Myocarditis:** This is an inflammatory condition of the heart muscle, usually viral. Treatment focuses on supportive care and managing heart failure; sGC stimulators have no role here. * **C. Atrial Fibrillation:** Managed with rate/rhythm control (e.g., Beta-blockers, Amiodarone) and anticoagulation. Riociguat does not possess anti-arrhythmic properties. * **D. Stroke:** Acute management involves thrombolysis or thrombectomy. Vasodilators like Riociguat are not used and could potentially worsen cerebral perfusion in acute settings. **High-Yield Clinical Pearls for NEET-PG:** 1. **Contraindication:** Never co-administer Riociguat with **PDE-5 inhibitors** (e.g., Sildenafil) or **Nitrates** due to the risk of severe, life-threatening hypotension. 2. **Teratogenicity:** It is contraindicated in pregnancy (Category X) and requires a restricted distribution program (REMS). 3. **Adverse Effect:** The most common side effect is hypotension and headache.

Question 264: Which of the following decreases defibrillation threshold?

A. Amiodarone
B. Verapamil
C. Sotalol (Correct Answer)
D. Diltiazim

Explanation: ### Explanation **Concept: Defibrillation Threshold (DFT)** The Defibrillation Threshold is the minimum electrical energy required to successfully terminate ventricular fibrillation. Drugs that **increase** DFT make it harder to defibrillate a patient, while drugs that **decrease** DFT make the heart more sensitive to electrical cardioversion. **Why Sotalol is Correct:** Sotalol is a Class III antiarrhythmic agent with potent potassium channel-blocking properties. By blocking the delayed rectifier potassium current ($I_{Kr}$), it prolongs the action potential duration (APD) and the effective refractory period (ERP). This increase in cardiac refractoriness lowers the energy required to terminate re-entrant circuits, thereby **decreasing the defibrillation threshold**. This property makes it particularly useful in patients with Implantable Cardioverter Defibrillators (ICDs). **Analysis of Incorrect Options:** * **Amiodarone:** Unlike Sotalol, chronic administration of Amiodarone is well-known to **increase** the DFT. This is a critical clinical consideration for patients with ICDs, as it may necessitate increasing the device's energy output settings. * **Verapamil and Diltiazem:** These are Class IV antiarrhythmics (Calcium Channel Blockers). While they affect the AV node and heart rate, they have **no significant effect** on the defibrillation threshold. **High-Yield Clinical Pearls for NEET-PG:** * **Drugs that Decrease DFT (Make defibrillation easier):** Sotalol, Dofetilide, and Bretylium. * **Drugs that Increase DFT (Make defibrillation harder):** Amiodarone, Lidocaine, Mexiletine, and Phenytoin. * **Sotalol Side Effect:** Being a Class III agent, the most feared complication of Sotalol is **Torsades de Pointes** due to QT interval prolongation. * **Amiodarone vs. Sotalol:** Remember that while both are Class III, they have opposite effects on DFT. Amiodarone increases it; Sotalol decreases it.

Question 265: Which of the following statins has the longest half-life?

A. Cerivastatin
B. Rosuvastatin (Correct Answer)
C. Atorvastatin
D. Simvastatin

Explanation: **Explanation:** Statins (HMG-CoA reductase inhibitors) are the first-line drugs for dyslipidemia. Their efficacy and dosing frequency are largely determined by their pharmacokinetic profile, specifically their elimination half-life. **1. Why Rosuvastatin is Correct:** **Rosuvastatin** has the longest half-life among the commonly used statins, lasting approximately **19–20 hours**. This prolonged duration allows for potent, 24-hour inhibition of the HMG-CoA reductase enzyme. Due to this long half-life, it can be administered at any time of the day, unlike short-acting statins which must be taken at bedtime to coincide with peak cholesterol synthesis. **2. Analysis of Incorrect Options:** * **Atorvastatin:** While also considered a "long-acting" statin, its half-life is approximately **14 hours**. It is the second longest after Rosuvastatin. * **Simvastatin:** This is a short-acting statin with a half-life of only **2–3 hours**. It is a prodrug and must be taken at night. * **Cerivastatin:** It has a short half-life (approx. 2–3 hours) and was **withdrawn from the market** globally due to a high incidence of fatal rhabdomyolysis. **3. High-Yield Clinical Pearls for NEET-PG:** * **Long Half-life Statins:** Rosuvastatin (~20h) > Atorvastatin (~14h) > Pitavastatin (~12h). These do not require nighttime dosing. * **Short Half-life Statins:** Lovastatin, Simvastatin, and Pravastatin. These should be taken at **bedtime** because hepatic cholesterol synthesis peaks between midnight and 2:00 AM. * **Hydrophilic Statins:** Rosuvastatin and Pravastatin. They have a lower risk of muscle toxicity (myopathy) compared to lipophilic statins (like Atorvastatin/Simvastatin) because they do not easily penetrate extrahepatic tissues. * **Potency:** Rosuvastatin is the most potent statin for lowering LDL-C.

Question 266: Beta blockers are contraindicated in which of the following conditions?

A. Angina pectoris
B. Cardiac arrhythmia
C. Cardiac failure (Correct Answer)
D. Myocardial infarction

Explanation: The correct answer is **Cardiac Failure**. Beta-blockers are competitive antagonists at $\beta_1$ receptors, leading to **negative inotropic** (decreased contractility) and **negative chronotropic** (decreased heart rate) effects [2]. In patients with **acute or decompensated heart failure**, the heart relies on high sympathetic drive to maintain cardiac output. Administering beta-blockers in this state can further reduce contractility, leading to a precipitous drop in cardiac output and worsening of the failure [3], [5]. **Why the other options are incorrect:** * **Angina Pectoris:** Beta-blockers are first-line therapy. They reduce myocardial oxygen demand by lowering heart rate and contractility, preventing ischemic episodes [2]. * **Cardiac Arrhythmia:** They are classified as Class II anti-arrhythmics [4]. They are particularly useful for rate control in atrial fibrillation and suppressing ventricular arrhythmias by slowing AV node conduction. * **Myocardial Infarction (MI):** Beta-blockers are standard post-MI care [2]. They reduce the risk of re-infarction and sudden cardiac death by limiting infarct size and preventing arrhythmias. **High-Yield Clinical Pearls for NEET-PG:** * **Paradox of Heart Failure:** While contraindicated in *acute* decompensated failure, specific beta-blockers (**Carvedilol, Metoprolol succinate, and Bisoprolol**) are mandatory in *stable, chronic* heart failure to prevent cardiac remodeling and reduce mortality [5]. * **Other Contraindications:** Always remember the "ABCDE" of beta-blocker contraindications: **A**sthma/COPD (due to $\beta_2$ blockade) [1], [4], **B**lock (Heart block) [3], **C**ardiogenic shock/Decompensated failure, **D**iabetes (masks hypoglycemia symptoms) [3], and **E**xtremity issues (Raynaud's/PVD). * **Prinzmetal Angina:** Beta-blockers are contraindicated here as they can cause unopposed alpha-mediated coronary vasoconstriction.

Question 267: Dipyridamole acts by:

A. Inhibiting thromboxane A2 synthesis
B. Antagonizing the uptake of adenosine by platelets (Correct Answer)
C. Calcium channel blocking property
D. None of the above

Explanation: ### Explanation **Dipyridamole** is a coronary vasodilator and antiplatelet agent. Its primary mechanism of action involves increasing the local concentration of **adenosine** and **cyclic AMP (cAMP)** within platelets and vascular smooth muscle. 1. **Why Option B is Correct:** Dipyridamole inhibits the cellular uptake of adenosine by platelets and vascular endothelium. This leads to increased extracellular levels of adenosine, which stimulates A2 receptors, increasing adenylate cyclase activity. This results in elevated intracellular **cAMP**, which inhibits platelet aggregation and causes vasodilation. Additionally, dipyridamole directly inhibits **phosphodiesterase (PDE3)**, the enzyme responsible for breaking down cAMP, further enhancing its antiplatelet effect. 2. **Why Other Options are Incorrect:** * **Option A:** Inhibition of thromboxane A2 (TXA2) synthesis is the mechanism of **Aspirin** (via irreversible COX-1 inhibition). * **Option C:** While dipyridamole is a vasodilator, it does not act through calcium channel blockade. Drugs like Nifedipine or Amlodipine belong to this class. ### High-Yield NEET-PG Pearls: * **Coronary Steal Phenomenon:** Dipyridamole can cause "coronary steal" by dilating healthy vessels, diverting blood away from ischemic areas. This property is utilized in **Dipyridamole Thallium Stress Testing** for patients unable to exercise. * **Clinical Use:** It is rarely used alone. It is most commonly combined with **Aspirin** (Aggrenox) for the secondary prevention of ischemic stroke and TIA, or with **Warfarin** for prophylaxis of thromboembolism in patients with prosthetic heart valves. * **Side Effects:** Headache (most common due to vasodilation) and dizziness.

Question 268: Which of the following drugs has the longest half-life?

A. Amiodarone (Correct Answer)
B. Quinidine
C. Diltiazem
D. Procainamide

Explanation: **Explanation:** The correct answer is **Amiodarone**. **1. Why Amiodarone is correct:** Amiodarone is a Class III antiarrhythmic drug known for its exceptional lipophilicity and extensive tissue distribution. It accumulates significantly in the adipose tissue, liver, and lungs. Due to this massive volume of distribution ($V_d$), it has an extraordinarily long elimination half-life, typically ranging from **25 to 60 days** (averaging several weeks). This necessitates the use of a loading dose to achieve steady-state plasma concentrations quickly. **2. Why the other options are incorrect:** * **Quinidine (Option B):** A Class IA antiarrhythmic with a half-life of approximately **6 to 8 hours**. * **Diltiazem (Option C):** A Class IV antiarrhythmic (Calcium Channel Blocker) with a relatively short half-life of **3 to 4.5 hours**, often requiring sustained-release formulations for long-term management. * **Procainamide (Option D):** A Class IA antiarrhythmic with a very short half-life of **3 to 4 hours**. Its active metabolite, N-acetylprocainamide (NAPA), has a longer half-life (6–10 hours) but is still significantly shorter than Amiodarone. **3. High-Yield Clinical Pearls for NEET-PG:** * **Iodine Content:** Amiodarone contains about 37% iodine by weight, leading to thyroid dysfunction (Hypothyroidism/Wolff-Chaikoff effect or Hyperthyroidism/Jod-Basedow phenomenon). * **Adverse Effects:** Due to its long half-life, toxicities take a long time to resolve. Key side effects include **pulmonary fibrosis** (most serious), corneal micro-deposits, bluish-grey skin discoloration, and hepatotoxicity. * **Monitoring:** Patients on long-term Amiodarone require regular Pulmonary Function Tests (PFTs), Liver Function Tests (LFTs), and Thyroid Function Tests (TFTs).

Question 269: A 23-year-old pregnant woman presents with features of dilated cardiomyopathy. Which of the following drugs should NOT be given for her treatment?

A. Digoxin
B. ACE inhibitors (Correct Answer)
C. Diuretics
D. Diuretics

Explanation: **Explanation:** The management of heart failure or dilated cardiomyopathy in pregnancy requires careful consideration of fetal safety. **1. Why ACE Inhibitors are Contraindicated:** ACE inhibitors (e.g., Enalapril, Lisinopril) and Angiotensin Receptor Blockers (ARBs) are strictly **contraindicated (Category X/D)** during pregnancy, especially in the second and third trimesters. They interfere with the fetal renin-angiotensin system, leading to **fetal renal dysgenesis**, oligohydramnios, pulmonary hypoplasia, intrauterine growth restriction (IUGR), and cranial ossification defects. If a patient is on these drugs and becomes pregnant, they must be switched to safer alternatives immediately. **2. Analysis of Other Options:** * **Digoxin:** It is considered safe during pregnancy (Category C) and is often used to control heart rate or improve contractility in maternal heart failure. * **Diuretics (e.g., Furosemide):** While used cautiously to avoid placental hypoperfusion due to volume depletion, they are not absolute contraindications and are frequently used to manage acute pulmonary edema in pregnant patients. * **Hydralazine and Nitrates:** These are the preferred vasodilators for afterload reduction in pregnant women with heart failure instead of ACE inhibitors. **Clinical Pearls for NEET-PG:** * **Teratogenic effect of ACEIs:** "Fetal Renal Tubular Dysgenesis" is a high-yield keyword. * **Safe Antihypertensives in Pregnancy:** Remember the mnemonic **"Better Mother Love Her Child"** — **B**eta-blockers (Labetalol), **M**ethyldopa (Drug of choice for chronic HTN), **L**abetalol, **H**ydralazine, **C**alcium Channel Blockers (Nifedipine). * **Peripartum Cardiomyopathy:** Usually occurs in the last month of pregnancy or within 5 months postpartum; Bromocriptine is sometimes used in its management.

Question 270: A patient presents to the casualty department in an unconscious state with a blood pressure of 220/110 mm Hg. What is the most suitable drug for this patient to rapidly decrease the blood pressure?

A. Sublingual nifedipine
B. Intramuscular injection of hydralazine
C. Intravenous infusion of sodium nitroprusside (Correct Answer)
D. Intravenous injection of clonidine

Explanation: ### Explanation **Correct Answer: C. Intravenous infusion of sodium nitroprusside** **Why it is correct:** The patient is presenting with a **Hypertensive Emergency** (BP >180/120 mmHg with signs of end-organ damage, evidenced here by an unconscious state/hypertensive encephalopathy). In such cases, the goal is a rapid but controlled reduction of blood pressure using **titratable intravenous medications**. **Sodium Nitroprusside** is a potent, ultra-short-acting vasodilator that acts on both arterioles and venules by releasing Nitric Oxide (NO). Its rapid onset (seconds) and short duration of action (1-2 minutes) allow for precise minute-to-minute titration, making it a classic choice for hypertensive emergencies. **Why other options are incorrect:** * **Sublingual Nifedipine:** This is **contraindicated** in hypertensive emergencies. It causes an unpredictable, precipitous drop in BP which can lead to reflex tachycardia and "steal phenomena," potentially causing cerebral ischemia or myocardial infarction. * **Intramuscular Hydralazine:** The IM route is avoided in emergencies because absorption is unpredictable, and the drug has a prolonged duration of action, making it difficult to "turn off" if the BP drops too low. * **Intravenous Clonidine:** While it can lower BP, it is not the preferred agent in emergencies due to its sedative effects (which would complicate the neurological assessment of an unconscious patient) and the risk of rebound hypertension. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice (DOC):** While Nitroprusside was traditionally the DOC, **Labetalol** or **Nicardipine** are now often preferred in many clinical settings due to fewer side effects. * **Nitroprusside Toxicity:** Prolonged infusion can lead to **Cyanide and Thiocyanate toxicity**. The antidote is Sodium Thiosulfate or Hydroxocobalamin. * **Rate of Reduction:** In emergencies, reduce MAP by no more than **25% within the first hour** to prevent organ hypoperfusion (except in aortic dissection).

Practice by Chapter

Antihypertensive Agents

Practice Questions

Drugs for Heart Failure

Practice Questions

Antiarrhythmic Drugs

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Antianginal Agents

Practice Questions

Lipid-Lowering Drugs

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Anticoagulants and Antiplatelet Drugs

Practice Questions

Thrombolytic Agents

Practice Questions

Drugs Used in Pulmonary Hypertension

Practice Questions

Drugs Used in Shock

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Cardiovascular Effects of Non-Cardiovascular Drugs

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