Cardiovascular Drugs Practice Questions

Q: Which receptor does dobutamine primarily act upon?

Beta 1. **Explanation:** Dobutamine is a synthetic catecholamine and a relatively selective **$\beta_1$-adrenergic agonist**. Its primary mechanism of action involves the stimulation of $\beta_1$ receptors in the myocardium, which increases intracellular cAMP levels. This leads to a potent **positive inotropic effect** (increased contractility) with a comparatively lesser effect on heart rate (chronotropy) and peripheral vascular resistance. **Analysis of Options:** * **Option A (Correct):** Dobutamine’s affinity for $\beta_1$ receptors is significantly higher than its affinity for other adrenergic receptors. This makes it the drug of choice for cardiogenic shock and acute heart failure. * **Option B ($\beta_2$):** While dobutamine has minor $\beta_2$ agonist activity (leading to mild vasodilation), this is not its primary site of action. * **Option C ($\alpha_1$):** Dobutamine exists as a racemic mixture; the (-) isomer is an $\alpha_1$ agonist, but the (+) isomer is an $\alpha_1$ antagonist. These effects largely cancel each other out, resulting in minimal net change in peripheral vascular resistance. * **Option D ($\alpha_2$):** Dobutamine has negligible activity at $\alpha_2$ receptors. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** Dobutamine is the preferred inotrope in **Cardiogenic Shock** because it increases cardiac output without significantly increasing myocardial oxygen demand compared to other pressors. * **Dobutamine Stress Echocardiography (DSE):** Used to diagnose ischemic heart disease in patients unable to perform exercise stress tests. * **Side Effect:** Can cause tachyarrhythmias (due to increased AV conduction). * **Comparison:** Unlike Dopamine, Dobutamine does not act on Dopaminergic ($D_1$) receptors and does not cause renal vasodilation.

Q: What is the agent of first choice in an acute attack of Prinzmetal's angina?

Nitrates. **Explanation:** **Prinzmetal’s (Variant) Angina** is characterized by transient coronary artery vasospasm rather than fixed atherosclerotic obstruction. The primary goal in an acute attack is to achieve rapid vasodilation of the coronary arteries to restore blood flow and relieve ischemia. **Why Nitrates are the Correct Answer:** Sublingual **Nitrates** (e.g., Nitroglycerin) are the **first-choice agents for acute attacks**. They act as potent vasodilators by increasing cyclic GMP in smooth muscle cells. Nitrates directly relax the coronary artery spasm, providing rapid symptomatic relief and reversing the ST-segment elevation seen on ECG. **Analysis of Incorrect Options:** * **Diltiazem & Verapamil (Options A & D):** These are Calcium Channel Blockers (CCBs). While CCBs are the **drugs of choice for long-term prophylaxis** of Prinzmetal’s angina because they prevent future spasms, they are not the first choice for terminating an *acute* attack as they do not act as rapidly as sublingual nitrates. * **Propranolol (Option C):** Beta-blockers are **contraindicated** in Prinzmetal’s angina. Blocking $\beta_2$ receptors leads to unopposed $\alpha$-adrenergic stimulation, which can worsen coronary vasospasm and exacerbate the condition. **NEET-PG High-Yield Pearls:** * **Classic Presentation:** Chest pain at rest, often occurring in the early morning, associated with transient ST-segment elevation. * **Gold Standard Diagnosis:** Coronary angiography with provocative testing (e.g., Ergonovine or Acetylcholine). * **Key Contraindication:** Always avoid non-selective beta-blockers in these patients. * **Smoking:** This is the most significant risk factor for variant angina.

Q: In which of the following patients would enalapril be the best first-line agent for high blood pressure control?

A 56-year-old diabetic woman. **Explanation:** **Why Option D is Correct:** Enalapril is an ACE inhibitor (ACEi). In patients with **Diabetes Mellitus**, ACE inhibitors are the first-line antihypertensive agents because they provide significant **nephroprotection**. They dilate the efferent arteriole more than the afferent arteriole, thereby reducing intraglomerular pressure. This mechanism slows the progression of diabetic nephropathy and reduces albuminuria, making it the drug of choice for this patient. **Why Other Options are Incorrect:** * **Option A (Renal Artery Stenosis):** ACE inhibitors are **contraindicated** in bilateral renal artery stenosis (or stenosis in a solitary kidney). These patients depend on Angiotensin II-mediated vasoconstriction of the efferent arteriole to maintain Glomerular Filtration Rate (GFR). Blocking this can precipitate acute renal failure. * **Option B (Pregnancy):** ACE inhibitors are **teratogenic** (Category D). They can cause fetal renal dysgenesis, oligohydramnios, and skull hypoplasia. Preferred agents in pregnancy include Labetalol, Methyldopa, or Hydralazine. * **Option C (Hyperkalemia):** ACE inhibitors reduce Aldosterone secretion, which leads to potassium retention. Administering enalapril to a patient with existing hyperkalemia can lead to life-threatening arrhythmias. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice (DOC):** ACE inhibitors are DOC for HTN in patients with Diabetes, Chronic Kidney Disease (proteinuric), and Heart Failure (reduced ejection fraction). * **Side Effects:** Remember the mnemonic **CAPTOPRIL** (Cough, Angioedema, Proteinuria, Taste changes, Orthostatic hypotension, Pregnancy contraindication, Renal artery stenosis contraindication, Increased potassium, Leukopenia). * **Dry Cough:** Caused by the accumulation of **Bradykinin** and Substance P in the lungs. If a patient develops a cough, switch them to an ARB (e.g., Losartan).

Q: A drug is a classical example of pharmacological success but therapeutic failure due to the coronary steal phenomenon. Which drug is it?

Dipyridamole. ### Explanation **Correct Option: B. Dipyridamole** **The Concept: Coronary Steal Phenomenon** Dipyridamole is a potent coronary vasodilator that acts by inhibiting adenosine deaminase and phosphodiesterase, leading to increased adenosine levels. While it is a "pharmacological success" because it effectively dilates coronary arteries, it is a "therapeutic failure" in treating angina due to the **Coronary Steal Phenomenon**. In a patient with coronary artery disease, vessels supplying ischemic areas are already maximally dilated by local metabolites. When dipyridamole is administered, it dilates the healthy, non-ischemic vessels. This reduces resistance in the healthy zones, "stealing" blood flow away from the stenosed, ischemic areas and diverting it to well-perfused areas, potentially worsening the ischemia. **Why other options are incorrect:** * **A. Glyceryl trinitrate (GTN):** GTN primarily causes venodilation (reducing preload) and dilates large epicardial coronary arteries without causing steal. It is the drug of choice for acute angina. * **C. Propranolol:** A beta-blocker that reduces myocardial oxygen demand by decreasing heart rate and contractility. It does not cause vasodilation or coronary steal. * **D. Diltiazem:** A calcium channel blocker that reduces heart rate and causes coronary vasodilation, but it does not typically induce the steal phenomenon to a clinically significant degree compared to dipyridamole. **High-Yield NEET-PG Pearls:** * **Clinical Use:** Because of its ability to induce "steal," Dipyridamole is used in **Thallium/Persantine Stress Testing** to identify ischemic areas in patients unable to exercise. * **Antiplatelet Action:** Dipyridamole is also used in combination with Aspirin for secondary stroke prevention. * **Other "Steal" drugs:** Hydralazine and Isoflurane are also associated with coronary steal.

Q: A patient with cardiac disease should be advised to stop which of the following medications if experiencing a persistent cough?

Enalapril. **Explanation:** **Correct Option: C. Enalapril** Enalapril is an **ACE (Angiotensin-Converting Enzyme) inhibitor**. The most characteristic side effect of ACE inhibitors is a **dry, persistent, non-productive cough**, occurring in approximately 5–20% of patients. * **Mechanism:** ACE is identical to Kininase II, the enzyme responsible for breaking down **Bradykinin** and **Substance P**. By inhibiting this enzyme, ACE inhibitors lead to an accumulation of these pro-inflammatory autacoids in the lungs. This irritates the sensory afferent C-fibers in the airways, triggering the cough reflex. * **Clinical Action:** If a patient develops this cough, the medication should be discontinued and replaced with an **ARB (Angiotensin Receptor Blocker)** like Losartan, which does not interfere with bradykinin metabolism. **Incorrect Options:** * **A. Diltiazem:** A non-dihydropyridine calcium channel blocker (CCB). Common side effects include bradycardia, constipation, and peripheral edema, but not cough. * **B. Aspirin:** An antiplatelet agent. While it can trigger "Aspirin-Exacerbated Respiratory Disease" (bronchospasm/asthma) in sensitive individuals, it does not typically cause a persistent dry cough. * **D. Clopidogrel:** A P2Y12 receptor antagonist. Its primary side effects are bleeding and gastrointestinal upset; it has no association with a cough. **High-Yield Clinical Pearls for NEET-PG:** * **ACEi Side Effects (Mnemonic: CAPTOPRIL):** **C**ough, **A**ngioedema, **P**roteinuria/Potassium excess (Hyperkalemia), **T**aste changes, **O**rthostatic hypotension, **P**regnancy contraindication (Teratogenic), **R**enal artery stenosis contraindication, **I**ncreased renin, **L**eukopenia. * The cough usually starts within 1 week to 6 months of therapy and typically resolves within 1–4 weeks after stopping the drug. * **Switching:** ARBs are the best alternative for patients who develop an ACEi-induced cough.

Q: Which of the following antiarrhythmic drugs does not cause Torsades de Pointes?

Lidocaine. **Explanation:** The risk of **Torsades de Pointes (TdP)** is directly linked to the prolongation of the **QT interval**. This occurs when a drug inhibits the outward potassium current ($I_K$), thereby delaying ventricular repolarization. **Why Lidocaine is the Correct Answer:** Lidocaine is a **Class IB antiarrhythmic**. Unlike other sodium channel blockers, Class IB drugs preferentially bind to sodium channels in the inactivated state and have a very rapid dissociation rate. Most importantly, Lidocaine **shortens the action potential duration (APD)** and the QT interval. Because it does not prolong repolarization, it carries a negligible risk of inducing Torsades de Pointes. **Why the Other Options are Incorrect:** * **Quinidine, Disopyramide, and Procainamide** are all **Class IA antiarrhythmics**. * The hallmark of Class IA drugs is that they block both fast sodium channels and **potassium channels**. * By blocking potassium channels, they significantly prolong the action potential duration and the **QT interval**. A prolonged QT interval creates a window of vulnerability for "early after-depolarizations" (EADs), which can trigger the polymorphic ventricular tachycardia known as Torsades de Pointes. **NEET-PG High-Yield Pearls:** * **Mnemonic for Class IA (QT prolongers):** "**Q**ueen **P**rom **D**isco" (**Q**uinidine, **P**rocainamide, **D**isopyramide). * **Class III drugs** (e.g., Sotalol, Ibutilide, Dofetilide) are also notorious for causing TdP due to potent potassium channel blockade. **Amiodarone** is a unique Class III drug that prolongs the QT interval but rarely causes TdP. * **Treatment of choice for TdP:** Intravenous **Magnesium Sulfate**, even if serum magnesium levels are normal.

Q: Which of the following is a venodilator?

Nitroprusside. ### Explanation **Sodium Nitroprusside** is the correct answer because it is a **balanced vasodilator**, meaning it acts on both the arterial (resistance) and venous (capacitance) vessels. **Mechanism of Action:** Nitroprusside acts by releasing **Nitric Oxide (NO)**, which stimulates guanylyl cyclase to increase intracellular **cGMP**. This leads to dephosphorylation of myosin light chains and relaxation of smooth muscles in both arterioles and venules. By dilating veins, it increases venous capacitance, thereby reducing **preload** (venous return to the heart). **Analysis of Incorrect Options:** * **A. Hydralazine:** This is a selective **arteriolar dilator**. It has minimal to no effect on the venous system. It is commonly used in pregnancy-induced hypertension. * **B. Minoxidil:** A potent **arteriolar dilator** that works by opening ATP-sensitive $K^+$ channels, causing hyperpolarization of smooth muscle. It is associated with reflex tachycardia and hypertrichosis. * **C. Nifedipine:** A Dihydropyridine **Calcium Channel Blocker (CCB)** that acts predominantly on the L-type calcium channels in the **arterial** smooth muscle. It does not possess significant venodilating properties. **High-Yield Clinical Pearls for NEET-PG:** * **Preload vs. Afterload:** Pure venodilators (like Nitroglycerin at low doses) reduce preload; pure arteriolar dilators (like Hydralazine) reduce afterload. Nitroprusside reduces **both**. * **Toxicity:** Prolonged infusion of Nitroprusside can lead to **Cyanide and Thiocyanate toxicity**. The antidote is Sodium Thiosulfate or Hydroxocobalamin. * **Light Sensitivity:** Nitroprusside is unstable in light; hence, the infusion bottle must be covered with opaque foil. * **Drug of Choice:** It was traditionally the drug of choice for **Hypertensive Emergencies**, though it is now often replaced by Labetalol or Nicardipine due to its toxicity profile.

Q: Which of the following drugs can cause glucose intolerance?

All of the above. **Explanation:** The correct answer is **D. All of the above**. Several classes of cardiovascular drugs can interfere with glucose metabolism, leading to hyperglycemia or "new-onset diabetes." 1. **Thiazides (e.g., Chlorthalidone, Hydrochlorothiazide):** These are the most common culprits. They cause glucose intolerance primarily through **hypokalemia**. Low extracellular potassium inhibits the release of insulin from pancreatic beta cells (as insulin secretion is a potassium-dependent process). They also decrease peripheral insulin sensitivity. 2. **Propranolol (Non-selective Beta-blockers):** Beta-blockers interfere with carbohydrate metabolism by inhibiting $\beta_2$-mediated insulin release and reducing peripheral glucose uptake. Furthermore, they mask the autonomic warning symptoms of hypoglycemia (like tachycardia and tremors), making them risky for diabetic patients. 3. **Furosemide (Loop Diuretics):** Similar to thiazides, loop diuretics can cause hyperglycemia, though generally to a lesser extent. The mechanism is again linked to hypokalemia-induced inhibition of insulin secretion. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of choice for HTN in Diabetics:** ACE inhibitors or ARBs (they are Reno-protective and metabolic-neutral). * **Metabolic Side Effects of Thiazides:** Remember the mnemonic **"Hyper-GLUC"** (Hyper**G**lycemia, Hyper**L**ipidemia, Hyper**U**ricemia, Hyper**C**alcemia). * **Beta-blocker exception:** Vasodilatory beta-blockers like **Carvedilol** and **Nebivolol** have a neutral or even beneficial effect on glycemic control compared to Propranolol. * **Potassium Link:** Maintaining normal serum potassium levels can often reverse or mitigate diuretic-induced glucose intolerance.

Question 1

Which receptor does dobutamine primarily act upon?

Accepted Answer

Beta 1

Answer

Beta 2

Answer

Alpha 1

Answer

Alpha 2

Question 2

What is the agent of first choice in an acute attack of Prinzmetal's angina?

Accepted Answer

Nitrates

Answer

Diltiazem

Answer

Propranolol

Answer

Verapamil

Question 3

In which of the following patients would enalapril be the best first-line agent for high blood pressure control?

Accepted Answer

A 56-year-old diabetic woman

Answer

A 62-year-old man with renal artery stenosis

Answer

A 32-year-old pregnant female

Answer

A 41-year-old woman with hyperkalemia

Question 4

A drug is a classical example of pharmacological success but therapeutic failure due to the coronary steal phenomenon. Which drug is it?

Accepted Answer

Dipyridamole

Answer

Glyceryl trinitrate

Answer

Propranolol

Answer

Diltiazem

Question 5

A patient with cardiac disease should be advised to stop which of the following medications if experiencing a persistent cough?

Accepted Answer

Enalapril

Answer

Diltiazem

Answer

Aspirin

Answer

Clopidogrel

Question 6

Which of the following antiarrhythmic drugs does not cause Torsades de Pointes?

Accepted Answer

Lidocaine

Answer

Quinidine

Answer

Disopyramide

Answer

Procainamide

Question 7

Which one of the following is NOT true in relation to angiotensin converting enzyme (ACE) inhibitors?

Accepted Answer

Contraindicated in diabetic nephropathy

Answer

May cause hyperkalemia in diabetic patients

Answer

Contraindicated in pregnancy

Answer

NSAIDs may impair its hypotensive effect

Question 8

A sixteen-year-old girl is found to have paroxysmal attacks of rapid heart rate. What is the antiarrhythmic of choice in most cases of acute AV nodal tachycardia?

Accepted Answer

Adenosine

Answer

Amiodarone

Answer

Propranolol

Answer

Quinidine

Question 9

Which of the following is a venodilator?

Accepted Answer

Nitroprusside

Answer

Hydralazine

Answer

Minoxidil

Answer

Nifedipine

Question 10

Which of the following drugs can cause glucose intolerance?

Accepted Answer

All of the above

Answer

Thiazides

Answer

Propranolol

Answer

Furosemide

Cardiovascular Drugs — MCQs

Cardiovascular Drugs — MCQs

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