Cardiovascular Drugs — MCQs

Cardiovascular Drugs Indian Medical PG Practice Questions and MCQs

Question 1141: Which of the following is the traditional first-line drug used for closure of patent ductus arteriosus?

A. Paracetamol
B. Alprostadil
C. Indomethacin (Correct Answer)
D. Celecoxib

Explanation: ***Indomethacin*** - This **prostaglandin synthesis inhibitor** is traditionally the first-line medication used to promote closure of a **patent ductus arteriosus (PDA)** in preterm infants. - It works by inhibiting **cyclooxygenase (COX) enzymes**, thereby reducing prostaglandin E2 (PGE2) levels, which are critical for maintaining ductal patency. *Paracetamol* - While sometimes used as an alternative, **paracetamol (acetaminophen)** is not the traditional first-line drug for PDA closure. - It has a weaker effect on prostaglandin synthesis compared to NSAIDs like indomethacin. *Alprostadil* - **Alprostadil (prostaglandin E1)** is used to **maintain** the patency of the ductus arteriosus in infants with severe congenital heart defects that require a patent ductus for systemic or pulmonary blood flow. - It works in direct opposition to the goal of PDA closure. *Celecoxib* - **Celecoxib** is a **selective COX-2 inhibitor** and is not typically used for PDA closure. - Its efficacy and safety profile for this specific indication have not been established as widely as indomethacin.

Question 1142: In the context of bilateral renal artery stenosis, which antihypertensive drug is considered contraindicated?

A. Beta-blockers
B. Calcium channel blockers
C. ACE inhibitors (Correct Answer)
D. Diuretics

Explanation: ***ACE inhibitors*** - In bilateral renal artery stenosis, ACE inhibitors can precipitate **acute kidney injury** by severely reducing **glomerular filtration pressure**, as both kidneys rely on **angiotensin II** for maintaining this pressure [1]. - They inhibit the production of **angiotensin II**, leading to **efferent arteriolar dilation** and a drop in glomerular hydrostatic pressure, which is critical for filtration in stenosed kidneys [2]. *Beta-blockers* - Beta-blockers are generally considered safe and effective in treating hypertension associated with renal artery stenosis, as they do not directly interfere with **renal autoregulation** in the same critical way as ACE inhibitors. - They lower blood pressure by reducing **cardiac output** and inhibiting renin release but do not acutely compromise **glomerular filtration** in the presence of stenosis. *Calcium channel blockers* - Calcium channel blockers are safe to use in bilateral renal artery stenosis and are often effective in controlling blood pressure. - They dilate **afferent arterioles**, which can actually help maintain or improve **glomerular filtration rate** by increasing blood flow to the glomerulus. *Diuretics* - Diuretics can be used cautiously in renal artery stenosis to manage blood pressure and fluid overload. - However, aggressive diuresis can lead to intravascular volume depletion, which might exacerbate **renal hypoperfusion** in already stenosed kidneys.

Question 1143: What is the mechanism of action of Verapamil?

A. Inhibition of calcium ion influx through L-type calcium channels (Correct Answer)
B. Blocking membrane depolarisation
C. Stabilization of cardiac membrane potential
D. Inhibition of calcium-dependent action potentials

Explanation: **Inhibition of calcium ion influx through L-type calcium channels** - **Verapamil** is a **non-dihydropyridine calcium channel blocker** that primarily acts by inhibiting the influx of calcium ions through **L-type calcium channels**. - This action on **voltage-gated L-type calcium channels** reduces intracellular calcium, leading to decreased myocardial contractility and vascular smooth muscle relaxation. *Blocking membrane depolarisation* - While calcium channel blockers affect electrical activity, their primary mechanism isn't simply blocking all **membrane depolarization**; rather, it's specific to calcium influx. - **Sodium channel blockers** are more directly associated with blocking membrane depolarization, especially in cardiac tissue. *Stabilization of cardiac membrane potential* - **Verapamil** primarily modulates the *rate of depolarization* and repolarization by affecting calcium influx, rather than universally stabilizing the basic resting membrane potential. - Drugs like **sodium channel blockers** are more classically described as stabilizing the cardiac membrane potential by altering rapid depolarization. *Inhibition of calcium-dependent action potentials* - While Verapamil reduces cellular activity that is *dependent* on calcium, its direct mechanism is the *inhibition of calcium influx*, which subsequently *reduces the amplitude and velocity of calcium-dependent action potentials.* - This option describes a consequence of its action rather than the *primary mechanism* at the channel level.

Question 1144: Which of the following is the longest acting ocular beta blocker?

A. Levobunolol (Correct Answer)
B. Carteolol
C. Betaxolol
D. Timolol

Explanation: ***Levobunolol*** - Levobunolol is the **longest-acting ocular beta-blocker**, with a duration of action of approximately **24 hours**, allowing for **once-daily dosing** in many patients. - It is a **non-selective beta-blocker** (blocks both beta-1 and beta-2 receptors) that effectively reduces intraocular pressure in glaucoma management. - Its extended duration makes it particularly convenient for patient compliance compared to other ocular beta-blockers. *Betaxolol* - Betaxolol is a **beta-1 selective blocker** with a duration of action of approximately **12 hours**, typically requiring **twice-daily dosing**. - Its selectivity may offer a better systemic safety profile regarding respiratory side effects compared to non-selective agents. - While effective, it does not have the longest duration of action among ocular beta-blockers. *Carteolol* - Carteolol is a **non-selective beta-blocker** with **intrinsic sympathomimetic activity (ISA)**. - It has a duration of action of approximately **12 hours** and usually requires **twice-daily administration**. - The ISA property may theoretically reduce some systemic side effects but does not extend its duration of action. *Timolol* - Timolol is a **non-selective beta-blocker** widely used in ophthalmology with a duration of action of approximately **12 hours**. - It typically requires **twice-daily dosing** and is highly effective for reducing intraocular pressure. - Its non-selective nature can lead to systemic side effects like **bronchospasm** in susceptible individuals.

Question 1145: What is the drug with the highest efficacy to increase plasma HDL?

A. Ezetimibe (Zetia)
B. Gemfibrozil (Lopid)
C. Rosuvastatin (Crestor)
D. Nicotinic acid (Niacin) (Correct Answer)

Explanation: ***Nicotinic acid (Niacin)*** - Niacin has the **highest efficacy** among lipid-lowering drugs in increasing **plasma HDL cholesterol** levels, often by 15-35%. - It works by reducing the **hepatic synthesis of VLDL** (and thus LDL) as well as increasing the half-life of HDL. *Ezetimibe (Zetia)* - Ezetimibe primarily acts by inhibiting the **absorption of cholesterol** from the intestine. - While it lowers LDL cholesterol, its effect on **increasing HDL** is modest at best, typically in the single digits. *Gemfibrozil (Lopid)* - Gemfibrozil is a **fibrate** that is best known for significantly lowering **triglycerides** and increasing HDL cholesterol modestly. - Its effects on HDL are generally **less robust** than those of niacin, usually in the range of 10-20%. *Rosuvastatin (Crestor)* - Rosuvastatin is a **statin**, which primarily works by inhibiting **HMG-CoA reductase**, leading to a significant reduction in LDL cholesterol. - While statins can cause a small increase in HDL, typically about 5-10%, this effect is **not its primary mechanism** of benefit nor its greatest strength compared to niacin.

Question 1146: Drug not used in pulmonary hypertension is:

A. Endothelin receptor antagonist
B. Prostacyclin
C. Alpha blocker (Correct Answer)
D. Calcium channel blocker

Explanation: ***Alpha blocker*** - Alpha-blockers primarily cause **systemic vasodilation** [1] and are not indicated for the specific pulmonary vascular remodeling and vasoconstriction seen in pulmonary hypertension. [2] - Their use could lead to an undesirable drop in **systemic blood pressure** [3] without adequately addressing the pulmonary arterial pressure. *Calcium channel blocker* - **Calcium channel blockers** (namely **dihydropyridines** like nifedipine and amlodipine) are used in a small subset of pulmonary hypertension patients who are **vasoreactive** on acute testing. - They work by relaxing pulmonary arterial smooth muscle, reducing **pulmonary vascular resistance**. *Endothelin receptor antagonist* - **Endothelin receptor antagonists** (e.g., bosentan, ambrisentan) block the effects of **endothelin-1**, a potent vasoconstrictor and smooth muscle proliferator involved in pulmonary hypertension. - They improve hemodynamics, exercise capacity, and clinical outcomes by preventing **vasoconstriction** and **vascular remodeling**. *Prostacyclin* - **Prostacyclin analogs** (e.g., epoprostenol, treprostinil) are potent **vasodilators** and inhibitors of platelet aggregation. - They are highly effective in treating severe pulmonary hypertension by relaxing pulmonary arteries and preventing **thrombosis**.

Question 1147: Digitalis acts in atrial fibrillation by

A. Increasing AV node refractoriness (Correct Answer)
B. Decreasing atrial contractility
C. Inhibiting Na+ K+ ATPase pump
D. Inhibiting Na+ H+ ATPase pump

Explanation: ***Increasing AV node refractoriness*** - **Digitalis** (digoxin) primarily works in atrial fibrillation by **increasing the refractoriness** of the **AV node** through enhanced **vagal tone**. - This action slows the conduction of electrical impulses from the atria to the ventricles, thereby controlling the **ventricular rate** - which is the therapeutic goal in AF. - This is the **clinical mechanism** by which digitalis treats atrial fibrillation. *Decreasing atrial contractility* - Digitalis has **positive inotropic effects** (increases contractility), not negative. - It increases both atrial and ventricular contractility through increased intracellular calcium. - This option is incorrect as it contradicts the fundamental action of digitalis. *Inhibiting Na+ K+ ATPase pump* - While this is the **molecular mechanism** of digitalis at the cellular level, it is not the direct answer to how digitalis "acts in atrial fibrillation." - Na+/K+ ATPase inhibition → increased intracellular Na+ → decreased Na+/Ca2+ exchange → increased intracellular Ca2+ → positive inotropy. - The question asks about the **therapeutic action in AF**, which is controlling ventricular rate through AV nodal effects, not the underlying molecular mechanism. - This is a common distractor - students must distinguish between molecular mechanism and clinical therapeutic action. *Inhibiting Na+ H+ ATPase pump* - Digitalis **does not inhibit the Na+/H+ exchanger**. - This pump is primarily involved in **pH regulation** and is not a target of cardiac glycosides. - This option is completely incorrect.

Question 1148: Which of the following is a contraindication for the use of digitalis?

A. WPW Syndrome (Correct Answer)
B. Thyrotoxicosis
C. Acute rheumatic carditis
D. Atrial fibrillation with rapid ventricular response

Explanation: ***WPW Syndrome*** - In **WPW syndrome**, digitalis can **accelerate conduction** through the accessory pathway, leading to a rapid and potentially life-threatening ventricular response, especially during **atrial fibrillation**. - This can trigger **ventricular tachycardia** or **ventricular fibrillation** in patients with pre-excitation. - This is an **absolute contraindication** to digitalis use. *Acute rheumatic carditis* - Acute rheumatic carditis is a **relative contraindication** to digitalis due to increased risk of **digitalis toxicity** in inflamed myocardium. - The inflamed heart muscle is more **sensitive to arrhythmogenic effects** of digitalis. - However, **WPW syndrome is a more absolute contraindication** as the mechanism of harm is more predictable and severe. - If heart failure is present, digitalis may be used with **extreme caution** under close monitoring. *Thyrotoxicosis* - While digitalis may be used cautiously in patients with thyrotoxicosis experiencing **tachyarrhythmias** or heart failure, it's not an absolute contraindication. - Digitalis effectiveness is **reduced in hyperthyroid states**, often requiring higher doses. - The primary treatment for thyrotoxicosis is to manage the **hyperthyroid state**, which often resolves the cardiac symptoms. *Atrial fibrillation with rapid ventricular response* - Digitalis is often used to **slow the ventricular rate** in atrial fibrillation with a rapid ventricular response by **increasing vagal tone** and inhibiting the AV node. - This is a common **indication** for digitalis therapy, not a contraindication.

Question 1149: Which of the following causes coronary vasodilation?

A. Adenosine (Correct Answer)
B. Noradrenergic stimulation
C. Hypocarbia
D. None of the options

Explanation: ***Adenosine*** - **Adenosine** is a potent **endogenous vasodilator** in the coronary circulation, released in response to myocardial ischemia and hypoxia. - It acts on **A2a receptors** on smooth muscle cells, leading to increased cAMP production and subsequent relaxation. *Noradrenergic stimulation* - **Noradrenergic stimulation** primarily causes **vasoconstriction** in most vascular beds, including the coronary arteries, through activation of **alpha-1 adrenergic receptors**. - While beta-2 receptors can cause vasodilation, the overall effect in the coronaries under strong noradrenergic stimulation is often vasoconstrictive or has a complex interplay. *Hypocarbia* - **Hypocarbia** (decreased CO2) leads to **vasoconstriction** in many vascular beds, including the cerebral circulation and, to a lesser extent, the coronary arteries. - This effect is mediated by the pH change in the smooth muscle cells; reduced CO2 causes **alkalosis**, which generally promotes vasoconstriction. *None of the options* - This option is incorrect because **adenosine** is a well-established and potent coronary vasodilator.

Question 1150: Hyperkalemia is associated with:

A. Thiazide diuretics (e.g., Chlorthalidone)
B. Antiarrhythmic agents (e.g., Amiodarone)
C. Angiotensin-converting enzyme (ACE) inhibitors (Correct Answer)
D. Loop diuretics (e.g., Furosemide)

Explanation: ***Angiotensin-converting enzyme (ACE) inhibitors*** - **ACE inhibitors** block the conversion of **angiotensin I to angiotensin II**, which reduces **aldosterone** secretion. - Reduced **aldosterone** leads to decreased **potassium excretion** in the kidneys, causing **potassium retention** and potentially **hyperkalemia**. - This is a well-known adverse effect, especially in patients with **renal impairment** or when combined with **potassium-sparing diuretics** or **potassium supplements**. *Thiazide diuretics (e.g., Chlorthalidone)* - **Thiazide diuretics** work by inhibiting the **sodium-chloride cotransporter** in the **distal convoluted tubule**, increasing sodium and water excretion. - This action typically leads to **hypokalemia** by increasing **potassium excretion**, not hyperkalemia. *Loop diuretics (e.g., Furosemide)* - **Loop diuretics** inhibit the **Na-K-2Cl cotransporter** in the **thick ascending limb of the loop of Henle**. - They are potent **potassium-wasting diuretics** that cause **hypokalemia** through increased renal potassium excretion, not hyperkalemia. *Antiarrhythmic agents (e.g., Amiodarone)* - **Amiodarone** is an antiarrhythmic agent that primarily acts by blocking **potassium channels** and has complex electrophysiological effects. - It is not directly associated with causing **hyperkalemia**; its primary electrolyte-related side effects involve thyroid function, not potassium homeostasis.

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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