Cardiovascular Drugs — MCQs

Cardiovascular Drugs Indian Medical PG Practice Questions and MCQs

Question 1051: Endothelin primarily acts through which type of receptors?

A. Calcium receptors
B. General receptor type (GPCRs)
C. Endothelin receptor type B (ETB)
D. Endothelin receptor type A (ETA) (Correct Answer)

Explanation: ***Endothelin receptor type A (ETA)*** - **ETA receptors** are primarily responsible for the **vasoconstrictive effects** of endothelin-1 in various tissues, leading to increased vascular tone and blood pressure. - Activation of **ETA receptors** on vascular smooth muscle cells mediates signaling pathways that result in **smooth muscle contraction**. *Endothelin receptor type B (ETB)* - **ETB receptors** have dual roles, mediating both **vasoconstriction** (via smooth muscle ETB) and **vasodilation** (via endothelial ETB, stimulating nitric oxide and prostacyclin release). - They also play a significant role in **clearance of endothelin-1** from circulation. *General receptor type (GPCRs)* - While **endothelin receptors (ETA and ETB)** are indeed **G protein-coupled receptors (GPCRs)**, "General receptor type (GPCRs)" is too broad and not the most specific answer for how endothelin *primarily acts*. - Endothelin's specific effects are mediated through its dedicated subtypes of GPCRs, not the general class. *Calcium receptors* - **Calcium receptors** (e.g., calcium-sensing receptors) are involved in sensing extracellular calcium levels and regulating calcium homeostasis. - Endothelin's mechanism involves **intracellular calcium mobilization** *after* receptor activation, but it does not act *through* calcium receptors.

Question 1052: What is the primary function of PGI2?

A. Is a vasodilator
B. Is pyrogenic
C. Inhibits platelet aggregation (Correct Answer)
D. None of the options

Explanation: ***Inhibits platelet aggregation*** - **PGI2 (prostacyclin)** is a potent inhibitor of **platelet aggregation** by increasing cAMP in platelets, preventing thrombus formation. - In the context of **cardiovascular pharmacology** and **hemostasis**, PGI2's antiplatelet action is clinically emphasized as its **primary therapeutic target**, especially when contrasted with **thromboxane A2 (TXA2)**, which promotes platelet aggregation. - PGI2 is often described as the body's **endogenous antiplatelet agent**, making this its most clinically significant function. - It also causes vasodilation (see below), but when discussing PGI2's "primary function" in most pharmacology contexts, the **antiplatelet effect** is highlighted. *Is a vasodilator* - **TRUE but incomplete**: PGI2 is indeed a potent **vasodilator** through smooth muscle relaxation. - However, many substances cause vasodilation, whereas PGI2's unique and clinically defining role in the **COX pathway** is its opposition to platelet aggregation. - Both functions are physiologically important and work synergistically, but in pharmacological classification, the **antiplatelet action** is typically considered the defining characteristic. *Is pyrogenic* - **Incorrect**: PGI2 does not cause fever. - **PGE2** (not PGI2) is the prostaglandin primarily associated with fever induction (pyrogenic effects). *None of the options* - Incorrect because **inhibits platelet aggregation** accurately describes PGI2's primary pharmacological function. - PGI2 has well-established roles in hemostasis and vascular biology.

Question 1053: Which of the following medications is primarily used to decrease serum triglycerides?

A. Fibrates (Correct Answer)
B. Ezetimibe
C. Niacin
D. Statin

Explanation: ***Fibrates*** - Fibrates, such as **gemfibrozil** and **fenofibrate**, are primarily used to activate **PPAR-alpha**, leading to increased lipoprotein lipase activity and reduced hepatic triglyceride synthesis. - This effectively lowers **serum triglyceride levels** by 20-50% and can also increase HDL cholesterol. *Statin* - Statins primarily inhibit **HMG-CoA reductase**, the rate-limiting enzyme in cholesterol synthesis, which makes them highly effective at lowering **LDL cholesterol**. - While they can cause a modest reduction in triglycerides (10-30%), this is not their primary mechanism or indication. *Ezetimibe* - Ezetimibe works by inhibiting the absorption of **cholesterol** at the brush border of the small intestine, thereby lowering **LDL cholesterol**. - It has minimal effect on **triglyceride levels** and is not indicated for primary triglyceride reduction. *Niacin* - Niacin, or **nicotinic acid**, reduces the liver's production of VLDL (which contains triglycerides) and LDL, and also increases HDL cholesterol. - While it can significantly lower triglycerides, its use is often limited by bothersome side effects such as **flushing** and itchiness, making fibrates generally preferred for primary triglyceride lowering due to better tolerability.

Question 1054: Digitalis is used in mitral stenosis to control the ventricular rate when the patient develops which condition?

A. Atrial fibrillation (Correct Answer)
B. Right ventricular failure
C. Acute pulmonary edema
D. Myocarditis

Explanation: ***Atrial fibrillation*** - **Digitalis** (digoxin) is effective in **slowing the ventricular rate** in atrial fibrillation by increasing vagal tone and prolonging the refractory period of the AV node. - In **mitral stenosis**, an uncontrolled rapid ventricular rate due to atrial fibrillation can significantly reduce cardiac output and worsen symptoms. *Right ventricular failure* - While digitalis can improve contractility, its primary role in **RV failure** is not rate control; diuretics and afterload reduction are more commonly used. - A patient with isolated right ventricular failure due to mitral stenosis would not directly benefit from digitalis for rate control. *Acute pulmonary edema* - **Acute pulmonary edema** requires rapid diuresis, oxygen, and vasodilators to reduce preload and afterload. - Digitalis has a slower onset of action and is not the first-line treatment for acute pulmonary edema, especially if the cause is not related to a rapid ventricular rate. *Myocarditis* - **Myocarditis** is an inflammation of the heart muscle, and digitalis is generally avoided due to concerns about potentially worsening arrhythmias and myocardial damage in an inflamed heart. - Treatment for myocarditis focuses on supportive care and addressing the underlying cause, not rate control with digitalis unless specific arrhythmias develop.

Question 1055: Which of the following adverse effects of ACE inhibitors is primarily due to the inhibition of aldosterone secretion?

A. Hyperkalemia (Correct Answer)
B. Respiratory tract irritation
C. Facial swelling
D. Hypotension

Explanation: ***Hyperkalemia*** - **Angiotensin II** stimulates aldosterone secretion, and **ACE inhibitors** block angiotensin II formation, leading to reduced aldosterone. - **Aldosterone** promotes sodium reabsorption and potassium excretion in the renal tubules, so its reduction causes **potassium retention** and **hyperkalemia**. - This is the primary adverse effect mediated through the **aldosterone pathway**. *Respiratory tract irritation* - This is primarily due to the accumulation of **bradykinin** and **substance P** in the airways, not due to the inhibition of aldosterone. - ACE is responsible for bradykinin breakdown, so its inhibition leads to **bradykinin accumulation** causing cough. *Facial swelling* - This is a symptom of **angioedema**, which is related to the accumulation of **bradykinin** due to ACE inhibition, not due to aldosterone inhibition. - Bradykinin causes **vasodilation** and increased vascular permeability. *Hypotension* - While hypotension can occur with ACE inhibitors, it is primarily due to reduced formation of the potent vasoconstrictor **angiotensin II**, causing **decreased systemic vascular resistance**. - This is NOT primarily mediated through the aldosterone pathway, but through direct vascular effects.

Question 1056: What is the mechanism of action of ticagrelor?

A. Reversible inhibition of ADP action (Correct Answer)
B. Irreversible inhibition of ADP action
C. Reversible inhibition of GPIIb/IIIa
D. Irreversible inhibition of GPIIb/IIIa

Explanation: ***Reversible inhibition of ADP action*** - **Ticagrelor** is a **P2Y12 receptor antagonist** that works by preventing ADP from binding to its receptor on platelets [2]. - This binding is **reversible**, meaning ticagrelor can dissociate from the receptor, allowing for some recovery of platelet function over time [2]. *Irreversible inhibition of ADP action* - **Clopidogrel** and **prasugrel** are examples of **irreversible P2Y12 inhibitors**, forming a permanent bond with the receptor [2]. - Irreversible inhibition leads to a longer duration of platelet inhibition, as new platelets must be generated for function to return [2]. *Reversible inhibition of GPIIb/IIIa* - **GPIIb/IIIa inhibitors** like **eptifibatide** and **tirofiban** block the final common pathway of platelet aggregation by preventing fibrinogen binding [1]. - While their action is reversible, they target a *different* mechanism than ticagrelor. *Irreversible inhibition of GPIIb/IIIa* - **Abciximab** is a GPIIb/IIIa inhibitor that binds **irreversibly** (or with very slow dissociation) to the receptor [1]. - Unlike reversible GPIIb/IIIa inhibitors, abciximab is a monoclonal antibody with a prolonged antiplatelet effect [1]. - This is still an incorrect answer as ticagrelor targets the P2Y12 receptor, not GPIIb/IIIa.

Question 1057: Which non-selective beta-blocker has sympathomimetic activity?

A. Nadolol
B. Pindolol (Correct Answer)
C. Acebutalol
D. Metoprolol

Explanation: ***Pindolol*** - **Pindolol** is a **non-selective beta-blocker** that exhibits **intrinsic sympathomimetic activity (ISA)**, meaning it acts as a partial agonist at beta-adrenergic receptors. - Due to ISA, it causes less reduction in resting heart rate and cardiac output compared to beta-blockers without ISA. *Acebutalol* - **Acebutalol** is a **beta-1 selective blocker** (cardioselective) that possesses **intrinsic sympathomimetic activity (ISA)**. - While it has ISA, it is not a non-selective beta-blocker, making it an incorrect answer for this question. *Nadolol* - **Nadolol** is a **non-selective beta-blocker** that does **not** have intrinsic sympathomimetic activity (ISA). - It primarily acts as a pure antagonist at both beta-1 and beta-2 adrenergic receptors. *Metoprolol* - **Metoprolol** is a **beta-1 selective blocker** (cardioselective) and does **not** possess intrinsic sympathomimetic activity (ISA). - Its primary action is blockade of cardiac beta-1 receptors.

Question 1058: Beta-blockers should be used with caution in patients with?

A. Hypertension
B. CHF
C. Conduction defect (Correct Answer)
D. Glaucoma

Explanation: ***Conduction defect*** - Beta-blockers **slow heart rate** and **decrease AV nodal conduction**, which can worsen pre-existing conduction defects like **AV block** or **sick sinus syndrome**. - Their use can lead to **symptomatic bradycardia** or complete heart block in susceptible individuals. - This represents a **strong relative contraindication** requiring significant caution. *Hypertension* - Beta-blockers are a **first-line treatment for hypertension**, effectively lowering blood pressure by reducing cardiac output and renin release. - They are generally **well-tolerated** and beneficial in most hypertensive patients. *Glaucoma* - Topical beta-blockers, such as **timolol**, are a common treatment for open-angle glaucoma as they **reduce aqueous humor production**, thereby lowering intraocular pressure. - Systemic use of beta-blockers does not typically worsen glaucoma and may even offer some benefit. *CHF* - While certain beta-blockers (**carvedilol, metoprolol succinate, bisoprolol**) are now proven beneficial in **chronic heart failure with reduced ejection fraction (HFrEF)**, they do require careful use. - They must be **initiated at low doses and carefully titrated** to avoid acute decompensation, and are **contraindicated in acute decompensated heart failure**. - However, **conduction defects** represent a **stronger contraindication** where beta-blockers can cause life-threatening bradycardia or complete heart block, making it the best answer for conditions requiring the most caution.

Question 1059: Which of the following is a lipid insoluble beta-blocker?

A. Timolol
B. Carvedilol
C. Pindolol
D. Celiprolol (Correct Answer)

Explanation: ***Celiprolol*** - **Celiprolol** is a **hydrophilic** (lipid-insoluble) beta-blocker, meaning it has low lipid solubility and does not readily cross the blood-brain barrier. - This property reduces the likelihood of **CNS side effects** such as nightmares and insomnia. *Timolol* - **Timolol** is a **lipophilic** (lipid-soluble) beta-blocker, allowing it to penetrate the central nervous system. - Its high lipid solubility contributes to a higher incidence of **CNS side effects**. *Carvedilol* - **Carvedilol** is a **lipophilic** mixed alpha and beta-blocker, which means it can cross the blood-brain barrier. - This can lead to central nervous system effects, although its primary clinical use is in heart failure and hypertension. *Pindolol* - **Pindolol** is a **lipophilic** beta-blocker with intrinsic sympathomimetic activity (ISA). - Its lipid solubility allows it to enter the brain, potentially causing **CNS-related side effects**.

Question 1060: Fenoldopam is used in the management of?

A. Hypertensive emergencies (Correct Answer)
B. Congestive heart failure
C. Migraine prophylaxis
D. Tachyarrhythmias

Explanation: ***Hypertensive emergencies*** - **Fenoldopam** is a **dopamine D1 receptor agonist** that causes rapid, dose-dependent peripheral vasodilation and increased renal blood flow, making it suitable for acute blood pressure reduction during hypertensive emergencies. - Its **rapid onset** and short half-life allow for precise control of blood pressure, and its **benefit** in preserving or improving renal function is particularly beneficial in patients with renal impairment. *Congestive heart failure* - While fenoldopam can increase renal blood flow, it is not a primary treatment for **congestive heart failure (CHF)** and is not typically used for its management. - Other drug classes, such as **diuretics**, **ACE inhibitors**, and **beta-blockers**, are the mainstays of CHF treatment. *Migraine prophylaxis* - Fenoldopam has **no role** in the prevention or acute treatment of migraines. - **Beta-blockers**, **calcium channel blockers**, and certain **antidepressants** are commonly used for migraine prophylaxis. *Tachyarrhythmias* - Fenoldopam **does not have antiarrhythmic properties** and is not indicated for the treatment of tachyarrhythmias. - **Beta-blockers**, **calcium channel blockers**, and specific **antiarrhythmic drugs** are used to manage tachyarrhythmias.

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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