Cardiovascular Drugs Practice Questions

Q: When treating hypertension chronically, orthostatic hypotension is maximum with which of the following medications?

Guanethidine. Guanethidine is the correct answer because it is a potent adrenergic neuron blocker. It works by inhibiting the release of norepinephrine from postganglionic sympathetic nerve endings and depleting catecholamine stores [1]. By profoundly blocking sympathetic outflow, it prevents the compensatory vasoconstriction that normally occurs upon standing. This leads to a severe drop in blood pressure, making orthostatic (postural) hypotension its most characteristic and dose-limiting side effect [1], [3]. **Analysis of Incorrect Options:** * **Clonidine (A):** An alpha-2 agonist that acts centrally to reduce sympathetic outflow. While it causes sedation and dry mouth, it rarely causes significant orthostatic hypotension because it does not completely paralyze peripheral sympathetic reflexes [2]. * **Prazosin (C):** A selective alpha-1 blocker. It is notorious for the **"first-dose phenomenon"** (severe syncope after the initial dose), but with chronic use, the risk of orthostatic hypotension is significantly less than that of Guanethidine. * **Propranolol (D):** A non-selective beta-blocker. It reduces blood pressure primarily by decreasing cardiac output and renin release. It does not interfere with alpha-mediated vasoconstriction; therefore, orthostatic hypotension is not a typical side effect. **High-Yield Clinical Pearls for NEET-PG:** * **Guanethidine** is rarely used today due to its side effect profile, which includes **explosive diarrhea** and **retrograde ejaculation**. * **Tricyclic Antidepressants (TCAs)** can block the uptake of Guanethidine into the neuron, thereby reversing its antihypertensive effect [1]. * **Rule of Thumb:** Drugs that interfere with peripheral sympathetic transmission (Guanethidine, Alpha-blockers) cause more orthostatic hypotension than those acting centrally (Clonidine) or on the heart (Beta-blockers).

Q: A 55-year-old man presents with erectile dysfunction and is prescribed sildenafil. He reports a marked improvement in his ability to sustain an erection with this treatment. The action of which of the following vasoactive mediators would primarily be prolonged in this patient?

Nitric Oxide. ### Explanation **Correct Option: D. Nitric Oxide** The physiological process of penile erection is mediated by the release of **Nitric Oxide (NO)** from parasympathetic nerve endings (nervi erigentes) and vascular endothelial cells [1]. NO activates the enzyme **guanylate cyclase**, which converts GTP into **cyclic Guanosine Monophosphate (cGMP)** [1]. cGMP acts as a second messenger that causes smooth muscle relaxation in the corpus cavernosum, leading to increased blood inflow. **Sildenafil** is a selective inhibitor of **Phosphodiesterase type 5 (PDE-5)**, the enzyme responsible for degrading cGMP. By inhibiting PDE-5, sildenafil prevents the breakdown of cGMP, thereby prolonging the vasodilatory action initiated by Nitric Oxide [1]. **Analysis of Incorrect Options:** * **A. Histamine:** While histamine can cause vasodilation, it is not the primary mediator of the erectile response and is not targeted by PDE-5 inhibitors. * **B. Endothelin-1:** This is a potent **vasoconstrictor**. Increased levels would oppose an erection rather than facilitate it. * **C. Prostacyclin (PGI2):** Although prostacyclin causes vasodilation via the cAMP pathway, sildenafil specifically targets the cGMP pathway associated with Nitric Oxide. **High-Yield Clinical Pearls for NEET-PG:** * **Innervation:** Parasympathetic fibers (S2–S4) via the **pelvic splanchnic nerves** are responsible for erection ("Point"), while Sympathetic fibers (T11–L2) are responsible for ejaculation ("Shoot"). * **Drug Interaction:** Sildenafil is strictly contraindicated in patients taking **Nitrates** (e.g., Nitroglycerin) because both increase cGMP, leading to life-threatening hypotension [2]. * **Site of Action:** PDE-5 is found predominantly in the **corpus cavernosum** and **pulmonary vasculature** (hence sildenafil's use in Pulmonary Arterial Hypertension).

Q: Alirocumab and Evolocumab are classified as which of the following?

PCSK-9 inhibitors. ### Explanation **Correct Option: C. PCSK-9 inhibitors** Alirocumab and Evolocumab are monoclonal antibodies that inhibit **Proprotein Convertase Subtilisin/Kexin type 9 (PCSK-9)**. * **Mechanism:** Normally, PCSK-9 binds to LDL receptors (LDLR) on the surface of hepatocytes and promotes their degradation. By inhibiting PCSK-9, these drugs increase the recycling and density of LDL receptors on the liver cell surface. * **Result:** Increased LDLRs lead to enhanced clearance of LDL-cholesterol from the plasma, resulting in a significant reduction (up to 60%) in LDL levels. **Why other options are incorrect:** * **A. NPGL1 inhibitors:** This likely refers to **Ezetimibe**, which inhibits the Niemann-Pick C1-Like 1 (NPC1L1) protein. It acts by blocking the intestinal absorption of dietary and biliary cholesterol. * **B. Microsomal transport protein (MTP) inhibitors:** The prototype drug is **Lomitapide**. It prevents the assembly of apoB-containing lipoproteins (VLDL and chylomicrons) in the liver and intestine. * **D. Lipoprotein lipase (LPL) inhibitors:** This is physiologically counterproductive for treating lipid disorders. Drugs like **Fibrates** actually *stimulate* LPL activity to enhance the clearance of triglyceride-rich lipoproteins. **High-Yield Clinical Pearls for NEET-PG:** * **Route of Administration:** These are administered as **subcutaneous injections** once every 2–4 weeks. * **Indications:** Used in patients with **Familial Hypercholesterolemia** or clinical atherosclerotic cardiovascular disease (ASCVD) who require additional LDL lowering despite maximally tolerated statin therapy. * **Side Effects:** Generally well-tolerated; most common side effects are injection site reactions and nasopharyngitis. * **Bempedoic Acid (Newer Drug):** Often tested alongside these; it inhibits **ATP citrate lyase**, acting upstream of HMG-CoA reductase.

Q: In which condition is Digoxin indicated for Congestive Heart Failure (CHF)?

Atrial fibrillation with a high ventricular rate. **Explanation:** Digoxin is a cardiac glycoside that exerts two primary effects: **positive inotropy** (by inhibiting Na+/K+ ATPase) and **negative chronotropy/dromotropy** (via vagomimetic action on the AV node). **Why Option C is Correct:** In patients with Congestive Heart Failure (CHF) and concomitant **Atrial Fibrillation (AF)**, Digoxin is highly effective. Its vagomimetic action slows conduction through the Atrioventricular (AV) node, thereby reducing the ventricular rate. This allows for better diastolic filling and improved cardiac output, making it a preferred choice for rate control in heart failure patients. **Why Other Options are Incorrect:** * **A. Hypertrophic Obstructive Cardiomyopathy (HOCM):** Digoxin is **contraindicated**. Increasing contractility (positive inotropy) in HOCM worsens the outflow tract obstruction, potentially leading to sudden cardiac collapse. * **B. High Output Failure:** Conditions like anemia, thyrotoxicosis, or thiamine deficiency cause heart failure due to excessive demand rather than primary pump failure. Digoxin is generally ineffective here as the underlying cause is metabolic or systemic, not a lack of contractility. **High-Yield NEET-PG Pearls:** * **Mechanism:** Inhibits Na+/K+ ATPase → increased intracellular Na+ → decreased Na+/Ca2+ exchange → increased intracellular Ca2+ → increased contractility. * **ECG Changes:** Characterized by the "reverse tick" or "Salvador Dali mustache" sign (ST-segment depression). * **Toxicity:** Hypokalemia predisposes to Digoxin toxicity. The most common arrhythmia in toxicity is **Ventricular Bigeminy**, while the most characteristic is **Non-paroxysmal Atrial Tachycardia with AV block**. * **Antidote:** Digibind (Digoxin-specific Fab fragments).

Q: Amyl nitrate is used by which route?

Inhalation. **Explanation:** **Amyl Nitrite** is a highly volatile liquid vasodilator belonging to the organic nitrate class. The correct route of administration is **Inhalation** because the drug is supplied in thin glass ampoules (crushable "pearls") wrapped in protective fabric. When crushed, the liquid vaporizes instantly and is inhaled through the nostrils, leading to rapid absorption across the pulmonary alveolar-capillary membrane. **Why the other options are incorrect:** * **Oral:** Amyl nitrite undergoes extensive **first-pass metabolism** in the liver, making oral administration ineffective. Furthermore, its rapid onset of action (within 30 seconds) is required for its clinical uses, which oral ingestion cannot provide. * **Intravenous:** While other nitrates like Nitroglycerin can be given IV, Amyl nitrite is specifically formulated for inhalation. IV administration is not standard due to the difficulty in titrating its extremely rapid and short-lived effect. * **Intramedullary:** This route (into the bone marrow) is reserved for emergency fluid resuscitation when IV access is impossible; it has no role in nitrate therapy. **Clinical Pearls for NEET-PG:** 1. **Mechanism in Cyanide Poisoning:** Amyl nitrite is a rapid-acting inducer of **Methemoglobinemia**. Methemoglobin has a high affinity for cyanide, forming **Cyanmethemoglobin**, which prevents cyanide from binding to Cytochrome Oxidase. 2. **Diagnostic Use:** In cardiology, it is used to differentiate heart murmurs. It **increases** the intensity of the murmur in **HOCM** and Mitral Regurgitation (due to decreased afterload) but decreases the murmur of Aortic Stenosis. 3. **Side Effects:** The most common side effect is a "throbbing" headache and orthostatic hypotension.

Q: In congestive cardiac failure, all of the following are used EXCEPT:

Trimetazidine. ### Explanation **Correct Answer: D. Trimetazidine** **1. Why Trimetazidine is the correct answer:** Trimetazidine is a **metabolic modulator** that inhibits the enzyme **3-ketoacyl-CoA thiolase (3-KAT)**. This shifts myocardial metabolism from fatty acid oxidation to glucose oxidation, which is more oxygen-efficient. While it is an effective **anti-anginal drug** used for chronic stable angina, it has no established role in the standard management of Congestive Cardiac Failure (CCF). It does not improve hemodynamics or mortality in heart failure patients. **2. Why the other options are used in CCF:** * **A. Spironolactone:** An aldosterone antagonist (MRA) that is a cornerstone of heart failure therapy. It prevents myocardial fibrosis and remodeling, significantly reducing mortality in patients with HFrEF (NYHA Class II-IV). * **B. Nitrates:** These are vasodilators. In acute heart failure, they reduce **preload** (venous dilation), relieving pulmonary congestion. In chronic cases, they are often combined with Hydralazine to reduce mortality, especially in specific populations. * **C. Nesiritide:** A recombinant form of **B-type Natriuretic Peptide (BNP)**. It causes vasodilation and natriuresis, used primarily in acute decompensated heart failure to reduce dyspnea and wedge pressure. **3. High-Yield Clinical Pearls for NEET-PG:** * **Drugs reducing mortality in CCF:** Beta-blockers (Carvedilol, Metoprolol, Bisoprolol), ACE inhibitors/ARBs, ARNIs (Sacubitril/Valsartan), Spironolactone, and SGLT2 inhibitors (Dapagliflozin). * **Trimetazidine Side Effect:** Can cause **Parkinsonian symptoms** (tremors, rigidity) and should be avoided in patients with Parkinson’s disease. * **Nesiritide** is contraindicated in patients with cardiogenic shock or systolic BP < 90 mmHg.

Q: Prolonged administration of sodium nitroprusside can cause poisoning of which substance?

Cyanide. Explanation: Sodium Nitroprusside (SNP) is a potent, rapid-acting vasodilator used in hypertensive emergencies [1]. Its chemical structure consists of a ferrous iron center surrounded by five cyanide (CN⁻) groups and one nitrosyl group. Why Cyanide is the correct answer: When SNP is administered intravenously, it reacts with hemoglobin and sulfhydryl groups in erythrocytes to release nitric oxide (the active vasodilator) and five cyanide ions. Normally, the liver enzyme rhodanese detoxifies cyanide by converting it into thiocyanate using sulfur donors (thiosulfate) [2]. However, with prolonged infusion (typically >24–48 hours) or high doses, the body’s thiosulfate stores are exhausted. This leads to cyanide accumulation, which inhibits mitochondrial cytochrome oxidase, causing cellular hypoxia and lactic acidosis. Why other options are incorrect: Methanol: Poisoning typically occurs via ingestion of adulterated alcohol, leading to formic acid accumulation. It is not a byproduct of SNP metabolism. Arsenic: A heavy metal toxin that inhibits pyruvate dehydrogenase; it is unrelated to vasodilator therapy. Phenol: Used as a disinfectant or chemical intermediate; it is not chemically related to the structure or metabolism of nitroprusside. High-Yield Clinical Pearls for NEET-PG: Early sign of toxicity: Metabolic acidosis (due to lactate) and an unexplained decrease in oxygen saturation (venous hyperoxemia). Management of SNP-induced Cyanide Poisoning: 1. Sodium Thiosulfate: Provides sulfur donors for rhodanese [2]. 2. Hydroxocobalamin (Vitamin B12a): Binds cyanide to form non-toxic cyanocobalamin (preferred first-line) [2]. 3. Amyl/Sodium Nitrite: Induces methemoglobinemia, which has a high affinity for cyanide [2]. Thiocyanate Toxicity: In patients with renal failure, the metabolite thiocyanate can accumulate, causing psychosis and seizures.

Q: What is the therapeutic plasma level of digoxin?

0.8-1.5 ng/ml. **Explanation:** Digoxin is a cardiac glycoside with a **narrow therapeutic index**, meaning the margin between a therapeutic dose and a toxic dose is very small [1]. Monitoring serum drug concentrations is critical for safety and efficacy. 1. **Why Option B is Correct:** The established therapeutic range for digoxin is generally **0.8–1.5 ng/ml** (some texts suggest 0.5–2.0 ng/ml). Within this range, the drug effectively increases vagal tone and inhibits the Na+/K+-ATPase pump to improve cardiac contractility and control ventricular rate in atrial fibrillation without causing significant toxicity [1], [2]. 2. **Why Other Options are Incorrect:** * **Option A (0.1–0.3 ng/ml):** This level is sub-therapeutic and will not provide the desired clinical effect. * **Option C (1.2–2 ng/ml):** While some patients may tolerate up to 2.0 ng/ml, levels above 1.5 ng/ml significantly increase the risk of toxicity, especially in patients with electrolyte imbalances [1], [2]. * **Option D (>2.4 ng/ml):** This is well into the **toxic range**. Digoxin toxicity typically manifests at levels >2.0 ng/ml [2]. **High-Yield Clinical Pearls for NEET-PG:** * **Toxicity Trigger:** Hypokalemia (low potassium) predisposes a patient to digoxin toxicity even if serum levels are within the "normal" range because potassium competes with digoxin for the Na+/K+-ATPase binding site. * **Antidote:** Digoxin-specific antibody fragments (**DigiFab/Digibind**) are used for life-threatening toxicity. * **ECG Changes:** The most common sign of toxicity is **PVCs** (Premature Ventricular Contractions); the most characteristic sign is **Paroxysmal Atrial Tachycardia with AV block** [3]. * **Visual Disturbance:** Xanthopsia (yellow-green vision) is a classic sign of digitalis toxicity.

Question 1

When treating hypertension chronically, orthostatic hypotension is maximum with which of the following medications?

Accepted Answer

Guanethidine

Answer

Clonidine

Answer

Prazosin

Answer

Propranolol

Question 2

A 55-year-old man presents with erectile dysfunction and is prescribed sildenafil. He reports a marked improvement in his ability to sustain an erection with this treatment. The action of which of the following vasoactive mediators would primarily be prolonged in this patient?

Accepted Answer

Nitric Oxide

Answer

Histamine

Answer

Endothelin-1

Answer

Prostacyclin

Question 3

Alirocumab and Evolocumab are classified as which of the following?

Accepted Answer

PCSK-9 inhibitors

Answer

NPGL1 inhibitors

Answer

Microsomal transport protein inhibitors

Answer

Lipoprotein lipase inhibitors

Question 4

In which condition is Digoxin indicated for Congestive Heart Failure (CHF)?

Accepted Answer

Atrial fibrillation with a high ventricular rate

Answer

Hypertrophic obstructive cardiomyopathy (HOCM)

Answer

High output failure

Answer

All of the above

Question 5

Amyl nitrate is used by which route?

Accepted Answer

Inhalation

Answer

Oral

Answer

Intravenous

Answer

Intramedullary

Question 6

In congestive cardiac failure, all of the following are used EXCEPT:

Accepted Answer

Trimetazidine

Answer

Spironolactone

Answer

Nitrates

Answer

Nesiritide

Question 7

Which of the following drugs reduces blood pressure primarily by directly decreasing heart rate?

Accepted Answer

Propranolol

Answer

Prazosin

Answer

Alpha methyl dopa

Answer

Nitroprusside sodium

Question 8

Tachycardia due to nitrates in a patient with angina pectoris is blocked by which of the following drug classes?

Accepted Answer

Beta blocker

Answer

Digoxin

Answer

Dobutamine

Answer

Calcium channel blocker

Question 9

Prolonged administration of sodium nitroprusside can cause poisoning of which substance?

Accepted Answer

Cyanide

Answer

Methanol

Answer

Arsenic

Answer

Phenol

Question 10

What is the therapeutic plasma level of digoxin?

Accepted Answer

0.8-1.5 ng/ml

Answer

0.1-0.3 ng/ml

Answer

1.2-2 ng/ml

Answer

More than 2.4 ng/ml

Cardiovascular Drugs — MCQs

Cardiovascular Drugs — MCQs

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