Cardiovascular Drugs Practice Questions

Q: All of the following are true about digoxin except:

It is 95% plasma protein bound. **Explanation:** The correct answer is **C** because Digoxin has **low plasma protein binding (approximately 20–25%)**. This is a high-yield pharmacokinetic fact; most of the drug is sequestered in skeletal muscle (its primary reservoir) rather than bound to albumin. **Analysis of Options:** * **Option A (True):** Digoxin exerts a **vagomimetic effect** on the SA and AV nodes. By increasing vagal tone, it slows the heart rate (negative chronotropy) and decreases conduction velocity through the AV node, making it useful in controlling ventricular rate in atrial fibrillation. * **Option B (True):** The primary mechanism of action is the inhibition of the **Na+/K+ ATPase pump** on the sarcolemma. This leads to an increase in intracellular Na+, which subsequently slows the Na+/Ca2+ exchanger, increasing intracellular Ca2+ levels and resulting in increased contractility (**positive inotropy**). * **Option D (True):** Digoxin is primarily eliminated **unchanged by the kidneys** via glomerular filtration. Its clearance is directly proportional to the Creatinine Clearance (CrCl), necessitating dose adjustments in renal failure. **High-Yield NEET-PG Pearls:** * **Volume of Distribution (Vd):** Digoxin has a very large Vd (~6–7 L/kg) because it binds extensively to skeletal muscle. * **Therapeutic Window:** It has a narrow therapeutic index (0.5–2.0 ng/mL). * **Toxicity:** Hypokalemia predisposes to digoxin toxicity because K+ and digoxin compete for the same binding site on the Na+/K+ ATPase pump. * **Antidote:** Digoxin-specific antibody fragments (**DigiFab**). * **ECG Changes:** Characterized by the "reverse tick" or "sagging" ST-segment depression (Salvador Dali mustache sign).

Q: Which antiarrhythmic drug is known to cause hypothyroidism?

Amiodarone. **Explanation:** **Amiodarone** is the correct answer because it is a Class III antiarrhythmic drug with a unique chemical structure containing approximately **37% iodine by weight**. Each 200 mg tablet provides about 75 mg of iodine, which is significantly higher than the daily requirement. The high iodine content can lead to thyroid dysfunction via two mechanisms: 1. **Hypothyroidism:** Occurs due to the **Wolff-Chaikoff effect**, where an iodine overload inhibits the synthesis of thyroid hormones. This is more common in iodine-sufficient areas. 2. **Hyperthyroidism:** Occurs via the **Jod-Basedow phenomenon** (excess iodine acting as a substrate for hormone synthesis) or through destructive thyroiditis. **Analysis of Incorrect Options:** * **B. Amrinone:** A phosphodiesterase-3 (PDE3) inhibitor used in heart failure. Its primary side effect is **thrombocytopenia**, not thyroid dysfunction. * **C. Digoxin:** A cardiac glycoside used for rate control in atrial fibrillation. Common toxicities include gastrointestinal upset, visual disturbances (xanthopsia), and various arrhythmias. * **D. Procainamide:** A Class IA antiarrhythmic. Its most characteristic high-yield side effect is **Drug-Induced Lupus Erythematosus (DILE)**, especially in slow acetylators. **High-Yield Clinical Pearls for NEET-PG:** * **Amiodarone Side Effects:** Remember the mnemonic **"6 P's"**: **P**ulmonary fibrosis (most serious), **P**hotosensitivity, **P**igmentation (Blue-gray skin), **P**eripheral neuropathy, **P**rolonged QT interval, and **P**arent (Thyroid) dysfunction. * **Monitoring:** Baseline and periodic Thyroid Function Tests (TFTs) and Liver Function Tests (LFTs) are mandatory for patients on long-term Amiodarone. * **Half-life:** Amiodarone has an exceptionally long half-life (approx. 3–8 weeks) due to its high lipid solubility.

Q: Which antiarrhythmic drug decreases both the rate of depolarization (phase 0) and the rate of repolarization of myocardial fibres?

Quinidine. **Explanation** The question describes the characteristic electrophysiological profile of **Class IA antiarrhythmics**. **1. Why Quinidine is Correct:** Quinidine belongs to **Class IA** of the Vaughan-Williams classification. Its mechanism involves: * **Sodium Channel Blockade (Phase 0):** It binds to open sodium channels, decreasing the slope of phase 0 (depolarization), which slows conduction velocity. * **Potassium Channel Blockade (Phase 3):** It blocks outward K+ channels, thereby prolonging the action potential duration (APD) and the effective refractory period (ERP). This manifests as a **decrease in the rate of repolarization**. * On an ECG, this corresponds to a widened QRS complex and a prolonged QT interval. **2. Why the other options are incorrect:** * **Verapamil (Class IV):** A calcium channel blocker. It primarily affects the SA and AV nodes by slowing Phase 0 of the nodal action potential (calcium-dependent), not the myocardial fiber depolarization. * **Propranolol (Class II):** A beta-blocker. It acts by decreasing sympathetic activity and slowing the heart rate; it does not significantly block sodium or potassium channels in myocardial fibers at standard doses. * **Lignocaine (Class IB):** While it blocks sodium channels (Phase 0), it actually **shortens** repolarization (Phase 3) or leaves it unchanged, unlike Class IA drugs which prolong it. **High-Yield NEET-PG Pearls:** * **Class IA Mnemonic:** "**P**olice **D**epartment **Q**uarters" (**P**rocainamide, **D**isopyramide, **Q**uinidine). * **Quinidine Side Effects:** Cinchonism (tinnitus, headache), thrombocytopenia, and *Torsades de Pointes* (due to QT prolongation). * **Drug Interaction:** Quinidine increases plasma levels of **Digoxin** by displacing it from tissue binding sites and reducing renal clearance.

Q: Supraventricular tachycardia can be managed best by:

Adenosine. **Explanation:** **Adenosine** is the drug of choice for the acute termination of Paroxysmal Supraventricular Tachycardia (PSVT), including those involving accessory pathways (WPW syndrome). It works by activating A1 receptors in the AV node, leading to increased potassium efflux and inhibition of calcium current. This results in profound hyperpolarization and a transient "chemical cardioversion" by blocking AV nodal conduction. Its ultra-short half-life (<10 seconds) makes it ideal for emergency use with minimal prolonged side effects. **Analysis of Incorrect Options:** * **Digitalis (Digoxin):** While it can be used for rate control in atrial fibrillation by increasing vagal tone, its onset of action is too slow (hours) for the acute management of SVT. * **Disopyramide & Quinidine:** These are Class IA antiarrhythmics. They are rarely used for SVT today due to their potential for pro-arrhythmia and significant side effects (e.g., anticholinergic effects of disopyramide, cinchonism with quinidine). Furthermore, they can paradoxically increase ventricular rate in atrial flutter/fibrillation by improving AV conduction. **High-Yield Clinical Pearls for NEET-PG:** * **Administration:** Adenosine must be given as a **rapid IV bolus** (usually 6mg, followed by 12mg) through a large-bore peripheral vein, followed by a saline flush, due to its rapid metabolism by erythrocytes and endothelial cells. * **Contraindications:** Avoid in **Asthmatics** (can cause bronchospasm via A2B receptors) and patients with **high-grade heart block**. * **Interactions:** Its effects are antagonized by **Theophylline/Caffeine** (adenosine receptor antagonists) and potentiated by **Dipyridamole**. * **Side Effects:** Patients often experience a transient, distressing sense of "impending doom," chest pain, or flushing.

Q: Which of the following drugs has been used in the treatment of angina by the inhalation route with a very rapid onset and short duration of action?

Amyl nitrite. **Explanation:** **Amyl nitrite** is the correct answer because it is a highly volatile liquid administered via **inhalation**. It is supplied in glass ampoules that are crushed and inhaled, leading to a very rapid onset of action (within 30 seconds) but a very short duration of effect (3–5 minutes). While it was historically used for acute angina, its primary clinical relevance today is in the emergency management of **cyanide poisoning** due to its ability to induce methemoglobinemia. **Why the other options are incorrect:** * **Isosorbide dinitrate (ISDN):** Primarily administered sublingually or orally. While sublingual ISDN has a rapid onset (2–5 minutes), it is not administered by inhalation and has a longer duration of action (1–2 hours) compared to Amyl nitrite. * **Isosorbide mononitrate (ISMN):** This is the active metabolite of ISDN. It has high oral bioavailability and a long half-life, making it suitable for the **prophylaxis** of angina, not for acute termination via inhalation. * **Nitroglycerin (Glyceryl Trinitrate):** The drug of choice for acute angina. It is typically administered sublingually (tablet or spray) or intravenously. While a lingual spray exists, it is not an "inhalational" drug that reaches the alveoli like Amyl nitrite. **High-Yield NEET-PG Pearls:** * **Cyanide Poisoning:** Amyl nitrite is used because it converts hemoglobin to **methemoglobin**, which has a high affinity for cyanide, forming non-toxic cyanmethemoglobin. * **Diagnostic Use:** In cardiology, Amyl nitrite inhalation is used to differentiate heart murmurs; it **increases** the intensity of the murmur in Hypertrophic Obstructive Cardiomyopathy (HOCM) and Mitral Regurgitation by decreasing systemic vascular resistance. * **Storage:** Organic nitrates (especially Nitroglycerin) must be stored in dark, tightly sealed glass containers because they are sensitive to light and can adsorb to plastic.

Q: A patient with hypertension also suffers from essential tremor. What is the optimal treatment for this patient?

Propranolol. **Explanation:** The correct answer is **Propranolol**. This is a classic "two birds, one stone" clinical scenario frequently tested in NEET-PG, where a single drug manages two comorbid conditions. **1. Why Propranolol is Correct:** Propranolol is a **non-selective beta-blocker** (blocking both $\beta_1$ and $\beta_2$ receptors). While $\beta_1$ blockade helps manage hypertension by reducing cardiac output and renin release [1], the **$\beta_2$ blockade** is crucial for treating essential tremors [2]. Essential tremors are mediated by peripheral $\beta_2$ receptors in the skeletal muscles; blocking these receptors reduces the amplitude of the tremors [2]. Its high lipid solubility also allows it to cross the blood-brain barrier, potentially contributing to its efficacy. **2. Why Other Options are Incorrect:** * **Clonidine:** An $\alpha_2$ agonist used for hypertension, but it has no effect on skeletal muscle tremors. * **Metoprolol:** A **cardioselective ($\beta_1$) blocker**. While effective for hypertension, it is significantly less effective than propranolol for essential tremors because it lacks potent $\beta_2$ receptor antagonism [2]. * **Lidocaine:** A Class Ib antiarrhythmic and local anesthetic. It has no role in the chronic management of hypertension or essential tremors. **3. Clinical Pearls for NEET-PG:** * **Drug of Choice (DOC):** Propranolol is the DOC for Essential Tremor and Prophylaxis of Migraine [1], [2]. * **Contraindications:** Avoid propranolol in patients with **Asthma or COPD** (due to $\beta_2$ blockade causing bronchoconstriction) and **Diabetes Mellitus** (masks hypoglycemia symptoms). * **Other uses:** It is also used in Performance Anxiety (Stage fright), Hyperthyroidism (to control symptoms and inhibit peripheral T4 to T3 conversion) [2], and Portal Hypertension [1].

Q: What is the treatment of choice for hypertension in patients with diabetes mellitus?

ACE Inhibitors. **Explanation:** **ACE Inhibitors (ACEIs)** are the treatment of choice for hypertension in patients with Diabetes Mellitus (DM) primarily due to their **renoprotective effects**. In diabetic patients, ACEIs (and ARBs) dilate the efferent arteriole more than the afferent arteriole. This reduces intraglomerular capillary pressure, thereby decreasing proteinuria and slowing the progression of diabetic nephropathy. **Why other options are incorrect:** * **Beta-blockers:** Generally avoided as first-line therapy in DM because they can mask the autonomic warning signs of hypoglycemia (like tachycardia and tremors) and may impair glucose tolerance by inhibiting insulin secretion. * **Thiazides:** While effective antihypertensives, they can cause hyperglycemia and worsen insulin resistance by inducing hypokalemia (which inhibits insulin release from the pancreas). * **Calcium Channel Blockers (CCBs):** These are metabolically neutral and effective, but they do not offer the same level of superior renal protection as ACEIs/ARBs in the presence of albuminuria. **High-Yield Clinical Pearls for NEET-PG:** * **First-line choice:** If a patient has DM with albuminuria or chronic kidney disease (CKD), ACEIs or ARBs are mandatory. * **Combination Therapy:** If blood pressure is not controlled with ACEIs alone, CCBs or Thiazides are typically added. * **Contraindication:** ACEIs are strictly contraindicated in pregnancy (teratogenic) and bilateral renal artery stenosis. * **Side Effect:** The most common side effect of ACEIs is a dry cough (due to bradykinin accumulation); in such cases, switch the patient to an **ARB (e.g., Losartan)**.

Q: Which of the following drugs is NOT used in the management of Congestive Cardiac Failure (CCF)?

Amiodarone. **Explanation:** The management of Congestive Cardiac Failure (CCF) focuses on reducing preload and afterload, improving contractility, and inhibiting maladaptive neurohumoral changes. **Amiodarone (Option D)** is primarily a **Class III Anti-arrhythmic agent**. While it is used to treat arrhythmias (like Atrial Fibrillation) that may occur *concurrently* with heart failure, it is not a standard drug for the management of CCF itself. In fact, most anti-arrhythmics are avoided in CCF due to their negative inotropic effects, though Amiodarone is considered the "safest" if an anti-arrhythmic is absolutely necessary. **Why other options are used in CCF:** * **Diuretics (Option A):** These are the mainstay for symptomatic relief. They reduce fluid overload and pulmonary congestion, thereby decreasing **preload**. * **Vasodilators (Option B):** Drugs like ACE inhibitors, ARBs, and Hydralazine/Nitrates reduce **afterload** and/or preload, decreasing the workload on the failing heart and improving survival. * **Dopamine/Dobutamine (Option C):** These are **Inotropic agents** used in acute or decompensated heart failure to increase cardiac contractility via $\beta_1$ receptor stimulation. **High-Yield Clinical Pearls for NEET-PG:** * **Drugs that improve survival in CCF:** ACE inhibitors, Beta-blockers (Carvedilol, Metoprolol, Bisoprolol), Spironolactone (MRAs), and ARNIs (Sacubitril/Valsartan). * **Digoxin:** Improves symptoms and reduces hospitalization but **does not** improve survival. * **Amiodarone side effects:** Pulmonary fibrosis, thyroid dysfunction (hypo/hyper), and corneal microdeposits are frequently tested.

Question 1

All of the following are true about digoxin except:

Accepted Answer

It is 95% plasma protein bound

Answer

Causes bradycardia due to increased vagal tone

Answer

Acts by inhibiting Na+K+ ATPase in myocardial fibres

Answer

Primarily excreted unchanged by glomerular filtration

Question 2

Which antiarrhythmic drug is known to cause hypothyroidism?

Accepted Answer

Amiodarone

Answer

Amrinone

Answer

Digoxin

Answer

Procainamide

Question 3

A 45-year-old female patient with essential hypertension was started on ramipril, furosemide, and aspirin. Two weeks later, she presented with well-controlled blood pressure but developed a persistent dry cough. Which alteration should be made to manage her cough without affecting her controlled blood pressure?

Accepted Answer

Replace ramipril with other angiotensin receptor blockers like valsartan.

Answer

Replace aspirin with clopidogrel.

Answer

Replace all drugs with beta blockers.

Answer

Replace furosemide with other diuretics.

Question 4

What is the drug of choice for ventricular tachycardia in a patient with myocardial ischemia?

Accepted Answer

Lignocaine

Answer

Propranolol

Answer

Diltiazem

Answer

Digoxin

Question 5

Which antiarrhythmic drug decreases both the rate of depolarization (phase 0) and the rate of repolarization of myocardial fibres?

Accepted Answer

Quinidine

Answer

Verapamil

Answer

Propranolol

Answer

Lignocaine

Question 6

Supraventricular tachycardia can be managed best by:

Accepted Answer

Adenosine

Answer

Digitalis

Answer

Disopyramide

Answer

Quinidine

Question 7

Which of the following drugs has been used in the treatment of angina by the inhalation route with a very rapid onset and short duration of action?

Accepted Answer

Amyl nitrite

Answer

Isosorbide dinitrate

Answer

Isosorbide mononitrate

Answer

Nitroglycerin

Question 8

A patient with hypertension also suffers from essential tremor. What is the optimal treatment for this patient?

Accepted Answer

Propranolol

Answer

Clonidine

Answer

Metoprolol

Answer

Lidocaine

Question 9

What is the treatment of choice for hypertension in patients with diabetes mellitus?

Accepted Answer

ACE Inhibitors

Answer

Beta blockers

Answer

Thiazides

Answer

Calcium channel blockers

Question 10

Which of the following drugs is NOT used in the management of Congestive Cardiac Failure (CCF)?

Accepted Answer

Amiodarone

Answer

Diuretics

Answer

Vasodilators

Answer

Dopamine/Dobutamine

Cardiovascular Drugs — MCQs

Cardiovascular Drugs — MCQs

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