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PHARMACOLOGY QUESTION BANK

Antihypertensives | Antianginals | CHF Drugs | Antiarrhythmics | Hypolipidemic Drugs

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PART A: CLINICAL CASE-BASED QUESTIONS

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CASE 1: Diabetic Hypertensive Patient

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Q1. What is the diagnosis?

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Q2. Which class of antihypertensive drugs is preferred? Give examples.

• Captopril (first ACE inhibitor developed; short-acting, not preferred for chronic therapy)
• Enalapril
• Lisinopril
• Ramipril (most commonly used)
• Perindopril
• Fosinopril, Quinapril, Benazepril, Trandolapril, Moexipril

• Losartan, Valsartan, Irbesartan, Candesartan, Telmisartan, Olmesartan

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Q3. Mechanism of Action

1. Inhibiting Angiotensin-Converting Enzyme (ACE/Kininase II): This enzyme normally converts angiotensin I (inactive) → angiotensin II (active vasoconstrictor). ACE inhibitors block this step, thereby reducing angiotensin II levels.
2. Reduced Angiotensin II effects:
   • Less vasoconstriction → decreased total peripheral resistance → BP falls
   • Less aldosterone secretion → reduced sodium and water retention → decreased plasma volume
   • Less sympathetic stimulation → reduced heart rate and cardiac output
3. Accumulation of Bradykinin: ACE also degrades bradykinin (a vasodilatory peptide). Inhibiting ACE raises bradykinin levels, contributing to vasodilation and also causing the class-specific adverse effect of dry cough.
4. Hemodynamic effects (long-term): ACE inhibitors decrease total peripheral resistance without increasing heart rate (no reflex tachycardia), maintain cardiac output, and slightly increase plasma renin activity.

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Q4. Adverse Effects and Contraindications

• Absolute: Pregnancy (Category D in 2nd/3rd trimester), history of angioedema, bilateral renal artery stenosis
• Relative: Severe renal impairment (creatinine >3 mg/dL), hyperkalemia (K+ >5.5 mEq/L)
• Do NOT combine ACE inhibitor + ARB + direct renin inhibitor (triple blockade - increased adverse events per VA NEPHRON-D trial)

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Q5. Why are ACE Inhibitors preferred in diabetic patients?

1. Renoprotective effect beyond BP lowering: ACE inhibitors reduce efferent arteriolar resistance in the glomerulus, decreasing intraglomerular pressure. This reduces proteinuria (microalbuminuria → macroalbuminuria progression is slowed).
2. Slow progression of diabetic nephropathy: Multiple trials (UKPDS, MICRO-HOPE) have shown ACE inhibitors slow the progression from microalbuminuria to overt nephropathy, even independently of blood pressure reduction.
3. Reduce cardiovascular events: Post-MI patients with reduced LV function benefit from ACE inhibitors with improved mortality. Diabetics are at higher cardiovascular risk.
4. Metabolically neutral: Unlike beta-blockers (which mask hypoglycemic symptoms and worsen insulin resistance) and thiazides (which cause hyperglycemia), ACE inhibitors do not adversely affect glucose or lipid metabolism.
5. Guidelines: National and international guidelines recommend ACE inhibitor or ARB for all forms of diabetic and non-diabetic CKD, especially in the presence of proteinuria ≥30 mg/day.

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CASE 2: Stable Angina - Nitroglycerin

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Q1. What is the diagnosis?

• Precipitated by exertion (increased O2 demand)
• Relieved by rest or nitroglycerin within 1-5 minutes
• Substernal chest pain/pressure, may radiate to arm, jaw
• Reproducible with similar levels of effort

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Q2. Mechanism of Action of Nitroglycerin

1. Nitroglycerin undergoes bioactivation (enzymatic denitration) in vascular smooth muscle, releasing nitric oxide (NO) - or a closely related NO-containing species.
2. NO activates soluble guanylyl cyclase (sGC), increasing intracellular cyclic GMP (cGMP).
3. cGMP activates protein kinase G (PKG), which:
   • Phosphorylates and inactivates myosin light chain kinase (MLCK)
   • Reduces intracellular Ca2+ availability
   • Opens K+ channels → membrane hyperpolarization
4. Result: vascular smooth muscle relaxation and vasodilation

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Q3. Why is Sublingual Administration Preferred?

1. Avoids first-pass hepatic metabolism: Oral nitroglycerin undergoes extensive first-pass metabolism in the liver (>90% destroyed before reaching systemic circulation), making oral bioavailability very low. Sublingual absorption bypasses the portal circulation.
2. Rapid onset of action: Rich submucosal capillary network under the tongue allows direct absorption into systemic venous circulation. Onset: 1-3 minutes - critical for acute anginal relief.
3. Short duration: Effects last 15-30 minutes, which is appropriate for acute attacks (not meant for sustained action).
4. Ease of use: Patient can self-administer immediately at the onset of an attack.

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Q4. Adverse Effects of Nitroglycerin

1. Headache - most common; due to meningeal vessel dilation (pulsating, throbbing)
2. Hypotension / syncope - postural hypotension from venodilation; especially with standing
3. Reflex tachycardia - from BP fall activating baroreceptors
4. Flushing - cutaneous vasodilation
5. Methemoglobinemia - at very high doses (rare clinically)
6. Tolerance (tachyphylaxis) - develops rapidly with continuous use; requires nitrate-free interval of 8-12 hours/day to prevent
7. Drug interactions: Absolute contraindication with PDE5 inhibitors (sildenafil, tadalafil) - additive hypotension, potentially fatal

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Q5. Drugs for Long-Term Prophylaxis of Angina

• Isosorbide dinitrate (ISDN) - 2-3 times daily (asymmetric dosing to avoid tolerance)
• Isosorbide mononitrate (ISMN) - once daily sustained-release
• Transdermal nitroglycerin patches (with nitrate-free interval)

• Atenolol, Metoprolol succinate, Bisoprolol, Carvedilol
• Mechanism: Reduce heart rate and myocardial contractility → reduce O2 demand
• Particularly beneficial in post-MI patients

• Dihydropyridines: Amlodipine, Nifedipine SR (for effort angina)
• Non-dihydropyridines: Verapamil, Diltiazem (for vasospastic angina also)
• Mechanism: Block L-type calcium channels → reduce smooth muscle contraction, reduce heart rate/contractility

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CASE 3: Heart Failure with Reduced Ejection Fraction (HFrEF)

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Q1. What is the diagnosis?

• EF <40% defines HFrEF (normal EF ≥55%)
• EF 35% confirms significant systolic dysfunction
• Classic symptoms: dyspnea on exertion, orthopnea, pedal edema, fatigue

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Q2. Drugs Used in CHF (Classification)

• Loop diuretics: Furosemide, Torsemide, Bumetanide
• Aldosterone antagonists: Spironolactone, Eplerenone
• Organic nitrates: Isosorbide dinitrate (in combination)

• ACE Inhibitors: Enalapril, Ramipril, Lisinopril
• ARBs: Valsartan, Losartan, Candesartan
• ARNI (Angiotensin Receptor-Neprilysin Inhibitor): Sacubitril/Valsartan (Entresto)
• Hydralazine (combined with nitrates in ACE inhibitor-intolerant patients)

• Cardiac glycosides: Digoxin
• Beta-adrenergic agonists: Dobutamine (acute/short-term)
• PDE-III inhibitors: Milrinone (acute)

• Beta-blockers: Carvedilol, Metoprolol succinate, Bisoprolol
• ACE inhibitors / ARBs
• Mineralocorticoid Receptor Antagonists (MRA): Spironolactone, Eplerenone

• SGLT2 Inhibitors: Dapagliflozin, Empagliflozin
• Ivabradine (If channel blocker - for elevated resting HR on beta-blockers)
• Vericiguat (sGC stimulator - for worsening HFrEF)

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Q3. Pharmacological Treatment of HFrEF

• First-line; reduce afterload and preload; inhibit cardiac remodeling
• Enalapril (CONSENSUS trial), Lisinopril, Ramipril
• Start low, titrate to target dose

• Counterintuitive use - initially worsen symptoms but long-term reduce mortality by ~34%
• Carvedilol (non-selective + alpha-1 blocker), Metoprolol succinate CR/XL, Bisoprolol
• Start only when patient is euvolemic (not in acute decompensation)
• Reduce sympathetic overactivation, prevent arrhythmias, reduce remodeling

• Spironolactone (RALES trial - 30% mortality reduction) or Eplerenone (post-MI HF)
• Block aldosterone-mediated myocardial fibrosis, sodium retention, K+ loss
• Monitor: Hyperkalemia, renal function

• Sacubitril inhibits neprilysin (enzyme that breaks down natriuretic peptides, bradykinin, angiotensin I)
• Valsartan blocks AT1 receptor
• PARADIGM-HF trial: Superior to enalapril - 20% relative risk reduction in CV death/HF hospitalization
• Replace ACE inhibitor/ARB with ARNI in patients who remain symptomatic
• Note: 36-hour washout required before switching from ACE inhibitor to ARNI to prevent angioedema

• For symptomatic relief of fluid overload - not proven to reduce mortality
• Essential for congestion management

• Dapagliflozin, Empagliflozin
• Proven mortality benefit regardless of diabetes status

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Q4. Role of SGLT2 Inhibitors in Heart Failure

1. Osmotic diuresis and natriuresis: Inhibiting SGLT2 in the proximal tubule increases urinary glucose and sodium excretion → reduces preload and plasma volume → relieves congestion
2. Reduction in afterload: Mild blood pressure reduction through natriuresis
3. Inhibition of Na+/H+ exchanger (NHE-1): In cardiomyocytes, reduces intracellular Na+ and Ca2+ overload - direct cardioprotective effect
4. Metabolic switch: Promotes ketone body utilization (ketones are a more efficient myocardial fuel than glucose or fatty acids - "thrifty substrate" hypothesis)
5. Anti-fibrotic and anti-inflammatory effects: Reduced cardiac fibrosis and oxidative stress
6. Reduction in epicardial fat: Reduces inflammation around coronary vessels

• DAPA-HF trial (dapagliflozin): 26% relative risk reduction in CV death + worsening HF, independent of diabetes status
• EMPEROR-Reduced (empagliflozin): 25% RR reduction in CV death + HF hospitalization

• HFrEF (EF <40%) - proven benefit
• HFmrEF and HFpEF (EF ≥40-50%) - emerging evidence (DELIVER trial with dapagliflozin showed benefit in HFmrEF/HFpEF)

• Genital mycotic infections
• UTI
• DKA (rare, mainly T1DM)
• Volume depletion (generally beneficial in HF, monitor in elderly)

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CASE 4: Hyperlipidemia in a Diabetic Patient

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Q1. What is the diagnosis?

• LDL 190 mg/dL is significantly elevated (normal <100 mg/dL for diabetics; <70 mg/dL for very high-risk patients)
• In a diabetic patient, this represents very high cardiovascular risk requiring aggressive lipid lowering
• Dietary modification alone insufficient → pharmacotherapy indicated

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Q2. Drug of First Choice

• Atorvastatin 40-80 mg/day (most commonly used)
• Rosuvastatin 20-40 mg/day

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Q3. Mechanism of Action

1. Competitive inhibition of HMG-CoA reductase: The rate-limiting enzyme in cholesterol biosynthesis is 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, which converts HMG-CoA → mevalonate. Statins competitively inhibit this step, reducing intracellular cholesterol synthesis.
2. Upregulation of LDL receptors: Reduced intracellular cholesterol causes the hepatocyte to upregulate LDLR (LDL receptor) gene expression via activation of SREBP-2 (sterol regulatory element-binding protein). More LDL receptors are expressed on hepatocyte surfaces.
3. Enhanced LDL clearance: Increased LDL receptors bind and internalize more LDL particles from the blood → LDL-C falls by 30-55% (dose-dependent).
4. Reduction in VLDL production: Less hepatic cholesterol reduces VLDL synthesis and secretion.
5. Pleiotropic effects (beyond lipid lowering):
   • Anti-inflammatory (reduce hsCRP, stabilize plaques)
   • Improve endothelial function (increase NO production)
   • Antithrombotic effects
   • Plaque stabilization (reduce macrophage infiltration, reduce lipid core)

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Q4. Adverse Effects of Statins

• CK (Creatine Kinase): Baseline; repeat if muscle symptoms develop
• LFTs (ALT/AST): Baseline; repeat at 8-12 weeks, then annually
• HbA1c: Monitor for new-onset diabetes

• Drugs that inhibit CYP3A4 (erythromycin, clarithromycin, cyclosporine, gemfibrozil, azole antifungals, HIV protease inhibitors) increase statin plasma levels → myopathy risk
• Fibrates (especially gemfibrozil) + statins = significantly increased rhabdomyolysis risk

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PART B: LONG ESSAY QUESTIONS

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LONG ESSAY 1: Antihypertensive Drugs

I. Classification

• Thiazides: Hydrochlorothiazide (HCTZ), Chlorthalidone, Indapamide
• Loop diuretics: Furosemide, Torsemide
• K+-sparing: Spironolactone, Eplerenone, Amiloride, Triamterene

• ACE Inhibitors: Captopril, Enalapril, Lisinopril, Ramipril, Perindopril
• ARBs: Losartan, Valsartan, Candesartan, Irbesartan, Telmisartan, Olmesartan
• Direct Renin Inhibitor: Aliskiren

• Dihydropyridines (vascular selective): Amlodipine, Nifedipine SR, Felodipine, Lercanidipine, Nicardipine
• Non-dihydropyridines: Verapamil (phenylalkylamine), Diltiazem (benzothiazepine)

• Beta-blockers: Atenolol, Metoprolol, Bisoprolol, Nebivolol, Propranolol, Carvedilol (mixed alpha+beta), Labetalol
• Alpha-1 blockers: Prazosin, Terazosin, Doxazosin
• Central alpha-2 agonists: Clonidine, Methyldopa, Moxonidine, Guanfacine

• Arterial: Hydralazine, Minoxidil, Diazoxide
• Arterial + venous: Sodium nitroprusside (IV emergency)

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II. Mechanism of Action

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III. Therapeutic Uses

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IV. Adverse Effects (Summary Table)

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V. Recent Recommendations in Hypertension

1. Target BP: <130/80 mmHg for most adults (ACC/AHA 2017); <140/90 mmHg (ESC/ESH 2018); diabetics <130/80 mmHg
2. Initial therapy: Single-pill combinations recommended for Stage 2 HTN (BP >160/100 mmHg) to improve adherence and early control
3. Preferred combination: ACE-I or ARB + CCB (amlodipine) + thiazide (chlorthalidone preferred over HCTZ for longer half-life)
4. RAAS inhibitors preferred in diabetes, CKD, proteinuria, post-MI, HFrEF
5. Beta-blockers no longer first-line for uncomplicated hypertension (moved to second-line unless compelling indication)
6. Resistant hypertension: Add spironolactone as 4th drug (PATHWAY-2 trial)
7. White coat hypertension: Ambulatory BP monitoring before diagnosis
8. Lifestyle modification always combined: DASH diet, weight loss, exercise, reduced sodium (<2.4 g/day), limit alcohol

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LONG ESSAY 2: Drugs Used in Congestive Heart Failure

Classification (by mechanism)

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Pharmacological Management of Acute Heart Failure (Decompensated)

1. IV Loop diuretics (furosemide bolus or continuous infusion): First-line for acute pulmonary congestion; rapidly reduce preload
2. IV Vasodilators (nitroglycerin, nitroprusside): Reduce preload and afterload; avoid if SBP <100 mmHg
3. IV Inotropes (dobutamine, milrinone): For cardiogenic shock or low cardiac output; bridge to recovery/transplant
   • Dobutamine: Beta-1 agonist → positive inotropy + chronotropy
   • Milrinone: PDE-III inhibitor → cAMP ↑ → inotropy + vasodilation ("inodilator")
   • Levosimendan: Ca2+ sensitizer → inotropy without increasing O2 demand
4. Morphine (controversial): Reduces anxiety, venodilation; current guidelines advise caution
5. Oxygen/NIV (BiPAP/CPAP) for respiratory failure

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Pharmacological Management of Chronic HFrEF

• Mechanism: Reduce AngII-mediated vasoconstriction, aldosterone, and cardiac remodeling
• ARNI (Sacubitril/Valsartan): Dual mechanism - neprilysin inhibition (increases natriuretic peptides BNP/ANP) + AT1 blockade
• Evidence: PARADIGM-HF (ARNI superior to enalapril; 20% RRR in primary endpoint)

• Mechanism: Counteract chronic sympathetic activation; reduce HR, prevent arrhythmias, reverse remodeling
• Start low, titrate slow; only initiate in stable, euvolemic patients
• Evidence: MERIT-HF (metoprolol), COPERNICUS (carvedilol), CIBIS-II (bisoprolol) - all ~30-35% mortality reduction

• Spironolactone: RALES trial - 30% mortality reduction in severe HF (EF <35%)
• Eplerenone: More selective, fewer gynecomastia side effects; used in post-MI HF
• Mechanism: Block aldosterone-mediated myocardial fibrosis, sodium retention, potassium depletion

• Dapagliflozin (DAPA-HF), Empagliflozin (EMPEROR-Reduced)
• Cardiorenal protective effects; reduce mortality and HF hospitalization

• Digoxin: Reduces HF hospitalizations, no mortality benefit; use for rate control in AF + HF
• Hydralazine + ISDN: For Black patients intolerant of RAAS inhibitors (A-HeFT trial)
• Ivabradine: Add-on if sinus rhythm, HR >70/min on maximum tolerated beta-blocker

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Role of Each Drug Class

• Reduce preload (less aldosterone → less sodium/water retention)
• Reduce afterload (vasodilation)
• Prevent and reverse cardiac remodeling
• First-line; titrate to highest tolerated dose

• Counter chronic sympathetic activation (NE is directly cardiotoxic)
• Slow heart rate → longer diastolic filling, better myocardial perfusion
• Prevent ventricular arrhythmias
• Evidence: All three proven agents provide ~30-35% mortality reduction

• Symptomatic relief only (no mortality benefit)
• Loop diuretics: First-line for fluid overload
• MRA: Disease-modifying (spironolactone, eplerenone)
• Use combination diuretics for diuretic resistance

• Superior to ACE inhibitor alone (PARADIGM-HF)
• First-line in HFrEF who can tolerate RAAS blockade
• Also lowers NTproBNP, reduces hospitalizations

• New class with strong evidence
• Independent of diabetes status
• Mechanism: Osmotic diuresis, natriuresis, cardioprotection, metabolic benefits

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LONG ESSAY 3: Antianginal Drugs

Classification

• Short-acting: Nitroglycerin (sublingual tablet/spray), Isosorbide dinitrate (sublingual)
• Long-acting: Isosorbide mononitrate (oral), Isosorbide dinitrate (oral), Transdermal nitroglycerin

• Non-selective: Propranolol, Nadolol
• Cardioselective (beta-1): Metoprolol, Atenolol, Bisoprolol
• Mixed alpha+beta: Carvedilol, Labetalol

• Dihydropyridines: Amlodipine, Nifedipine SR, Felodipine (vascular selective)
• Non-DHPs: Verapamil (phenylalkylamine), Diltiazem (benzothiazepine) - also cardiac effects

• Ranolazine: Inhibits late Na+ current
• Ivabradine: If-channel blocker (pure HR reduction)
• Trimetazidine: Metabolic agent (inhibits fatty acid oxidation, promotes glucose utilization)
• Nicorandil: K+ channel opener + nitrate effect

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Mechanisms

• Decrease heart rate (negative chronotropy)
• Decrease contractility (negative inotropy)
• Reduce blood pressure
• Net: Markedly reduce myocardial O2 demand
• Also shift O2 supply-demand by prolonging diastole (more time for coronary perfusion)

• In vascular smooth muscle: Vasodilation (reduce afterload)
• In heart (non-DHP): Reduce HR and contractility
• In coronary vessels: Prevent and relieve coronary vasospasm (mechanism of choice in Prinzmetal angina)
• DHP (amlodipine): Pure vasodilation; reflex tachycardia can occur (combine with beta-blocker)

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Management by Angina Type

• Acute relief: SL nitroglycerin
• Long-term prophylaxis: Beta-blocker (first-line) OR CCB (amlodipine)
• Add nitrate or ranolazine if monotherapy inadequate
• Combination: Beta-blocker + DHP-CCB is very effective
• Revascularization (PCI/CABG) for refractory cases

• Antiplatelet: Aspirin + P2Y12 inhibitor (clopidogrel/ticagrelor)
• Anticoagulant: LMWH (enoxaparin) or UFH
• IV nitroglycerin for persistent pain
• Beta-blocker (oral)
• High-intensity statin
• ACE inhibitor
• Early invasive strategy in high-risk patients

• CCBs are drug of choice: Amlodipine, Verapamil, Diltiazem - relieve and prevent coronary vasospasm
• Long-acting nitrates: Second-line or add-on
• Beta-blockers are CONTRAINDICATED (can worsen vasospasm by leaving alpha-adrenergic vasoconstriction unopposed)

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LONG ESSAY 4: Hypolipidemic Drugs

Classification

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Mechanisms

• ↓ LDL by 30-55%
• Modest ↑ HDL (5-10%)
• Modest ↓ TG (10-20%)
• Pleiotropic effects: Anti-inflammatory, antithrombotic, plaque stabilization

• ↓ TG by 30-50%
• ↑ HDL by 10-20%
• Modest ↓ LDL
• Primary use: Hypertriglyceridemia

• ↓ LDL by 15-30%
• May increase TG (contraindicated if TG >400 mg/dL)

• ↓ LDL by 15-20% additional on top of statin (complementary mechanism per Goodman & Gilman's)
• Used in combination with statins (IMPROVE-IT trial: modest additional CV benefit)

• Monoclonal antibodies; given SC every 2-4 weeks
• Used for: Familial hypercholesterolemia, statin-intolerant patients, very high-risk patients not at goal

• Best agent for raising HDL (+25-35%)
• ↓ TG (25-35%), ↓ LDL (10-20%)
• Adverse effects: Flushing (prostaglandin-mediated; prevented by aspirin 325 mg before dose), hepatotoxicity, hyperglycemia, hyperuricemia, acanthosis nigricans

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Adverse Effects and Therapeutic Uses Summary

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PART C: SHORT ESSAY QUESTIONS

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Short Essay 1: ACE Inhibitors - Mechanism, Uses, Adverse Effects

1. Hypertension (first-line for diabetes, CKD, post-MI, HFrEF)
2. Heart failure with reduced EF (reduces mortality - CONSENSUS, SOLVD trials)
3. Post-MI (reduces LV remodeling, mortality)
4. Diabetic nephropathy (renoprotection beyond BP control)
5. Secondary prevention in high cardiovascular risk (HOPE trial - ramipril)
6. Scleroderma renal crisis

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Short Essay 2: Calcium Channel Blockers in Hypertension and Angina

• DHP (vascular selective): Amlodipine, Nifedipine SR, Felodipine, Nicardipine
• Non-DHP: Verapamil (phenylalkylamine), Diltiazem (benzothiazepine)

• In vascular smooth muscle: Vasodilation (all CCBs)
• In heart: ↓ contractility, ↓ SA node rate, ↓ AV nodal conduction (mainly non-DHPs)

• Amlodipine: First-line; long half-life (t½ = 30-50 hours), once daily, no reflex tachycardia; preferred in elderly, isolated systolic HTN, coexisting angina
• Verapamil/Diltiazem: Alternative; also useful with coexisting AF for rate control

• All CCBs reduce O2 demand via vasodilation (↓ afterload) and (non-DHP) ↓ HR/contractility
• DHP CCBs: Preferred for stable angina (combine with beta-blocker to offset reflex tachycardia)
• Non-DHP CCBs: Preferred for vasospastic (Prinzmetal) angina (prevent coronary vasospasm)
• Amlodipine: Safe in HF with reduced EF (PRAISE trial); unlike non-DHPs

• DHP: Peripheral edema (dose-dependent, ankle edema), flushing, headache, reflex tachycardia
• Non-DHP: Bradycardia, AV block, constipation (verapamil prominently), worsening HFrEF

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Short Essay 3: Beta-Blockers in Cardiovascular Diseases

• Non-selective (beta-1 + beta-2): Propranolol, Nadolol, Timolol, Sotalol
• Cardioselective (beta-1 preferential): Atenolol, Metoprolol, Bisoprolol, Esmolol, Acebutolol
• Mixed alpha + beta: Labetalol, Carvedilol
• With ISA: Acebutolol, Pindolol

• Bradycardia, AV block
• Bronchospasm (non-selective; avoid in asthma/COPD)
• Cold extremities (beta-2 blockade reduces peripheral vasodilation)
• Fatigue, exercise intolerance
• Masking of hypoglycemic symptoms (avoid non-selective in brittle diabetes)
• Sexual dysfunction
• Dyslipidemia (increase TG, reduce HDL - mainly non-selective)
• Rebound hypertension on abrupt withdrawal

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Short Essay 4: Digoxin - Mechanism, Uses, Adverse Effects, Toxicity

1. Inhibits Na+/K+-ATPase (sodium pump): Digoxin binds to the extracellular face of the Na+/K+-ATPase. This inhibits the pump → intracellular Na+ rises.
2. Secondary Ca2+ rise via Na+/Ca2+ exchanger: The Na+/Ca2+ exchanger (NCX) normally uses the Na+ gradient to extrude Ca2+. When intracellular Na+ rises, NCX works less effectively → intracellular Ca2+ accumulates.
3. Positive inotropy: Increased intracellular Ca2+ stored in SR → more Ca2+ released per action potential → stronger contraction (increased contractility).
4. Cardiac slowing (negative chronotropy/dromotropy):
   • Vagomimetic effect: Enhances vagal tone → slows SA node, prolongs AV node conduction time
   • Useful for rate control in AF

1. Heart failure with reduced EF (reduces hospitalizations, no mortality benefit - DIG trial)
2. Rate control in atrial fibrillation and atrial flutter
3. Paroxysmal SVT (now second-line; adenosine preferred)

• Cardiac toxicity:
  • Premature ventricular contractions (PVCs) - most common
  • Bigeminy, trigeminy
  • Paroxysmal atrial tachycardia with AV block ("PAT with block") - PATHOGNOMONIC of digoxin toxicity
  • VT/VF - can be fatal
  • SA block, AV block (bradyarrhythmias)
• Non-cardiac toxicity:
  • GI: Nausea, vomiting, anorexia (often first signs)
  • CNS: Visual disturbances (yellow/green halos - xanthopsia), blurred vision, confusion, delirium
  • Gynecomastia (men) - from estrogen-like activity

• Hypokalemia (most important): K+ and digoxin compete for the same binding site on Na+/K+-ATPase. Low K+ → more digoxin binds → toxicity at "normal" serum levels
• Hypomagnesemia, hypercalcemia
• Renal failure (digoxin is renally cleared)
• Thyroid disease (hypothyroidism increases sensitivity)
• Drug interactions: Amiodarone, verapamil, quinidine (all increase serum digoxin levels)

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Short Essay 5: Statins - Mechanism, Adverse Effects, and Monitoring

• Myopathy (5-10% myalgia; rare rhabdomyolysis - CK >10× ULN)
• Elevated AST/ALT (monitor LFTs)
• New-onset diabetes (dose-dependent, ~10% increase in risk)
• Teratogenicity (contraindicated in pregnancy)

• Baseline: Fasting lipids, LFTs (ALT), CK, HbA1c/fasting glucose
• Follow-up: Fasting lipid panel at 4-12 weeks after initiation and dose change, then annually
• CK: Only if symptomatic (muscle pain, weakness); discontinue if CK >10× ULN
• LFTs: At baseline and if symptoms of hepatotoxicity develop (not routine periodic)
• LDL goal: Reduction ≥50% from baseline OR absolute goal (<70 mg/dL for very high-risk, <55 mg/dL for extreme-risk patients per 2019 ESC)

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Short Essay 6: Vaughan Williams Classification of Antiarrhythmics

• Amiodarone (Class III) also has Class I, II, and IV properties - the "all-class" drug
• Sotalol = Class II + III properties (beta-blocker + K+ channel blockade)
• CAST trial: Class IC drugs (flecainide, encainide) increased mortality in post-MI patients despite suppressing PVCs - arrhythmia suppression ≠ improved outcomes

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PART D: GIVE REASON (SHORT ANSWERS)

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1. Why are ACE inhibitors preferred in diabetic hypertensive patients?

1. Reduce intraglomerular hypertension: Ang II constricts the efferent glomerular arteriole preferentially. ACE inhibitor removes this efferent constriction → reduces glomerular capillary pressure → less mechanical injury to glomerular filtration barrier → reduces proteinuria.
2. Reduce protein filtration: Lower intraglomerular pressure decreases protein leak → slows progression from microalbuminuria to macroalbuminuria to ESRD.
3. Anti-inflammatory and anti-fibrotic effects: Less Ang II → reduced TGF-beta activity → less glomerular and interstitial fibrosis.
4. Metabolic neutrality: No adverse effects on glucose or lipids (unlike beta-blockers and thiazides).
5. Cardiovascular protection: Reduce mortality, MI, stroke in high-risk diabetics (HOPE trial - ramipril 10 mg reduced major CV events by 22% in diabetics).
6. Guidelines recommendation: All major guidelines (ADA, ESC, ACC/AHA) recommend ACE inhibitor or ARB as first-line antihypertensive in diabetes with microalbuminuria or CKD.

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2. Why is nitroglycerin administered by the sublingual route during an acute anginal attack?

1. Avoids hepatic first-pass metabolism: Oral nitroglycerin is nearly completely inactivated by the liver before reaching systemic circulation (>90% first-pass extraction). Sublingual administration bypasses the portal system.
2. Rapid onset: The sublingual mucosa is highly vascular; absorption into systemic venous circulation begins within 1-2 minutes. Onset of action: 1-3 minutes - essential for aborting an acute anginal episode.
3. Adequate bioavailability: Only 1-3% of the liver dose is required sublingually to achieve therapeutic blood levels.
4. Short duration: Action lasts 15-30 minutes - appropriate for the acute attack without prolonged hemodynamic effects.
5. Patient control: Can be self-administered at the first onset of symptoms.

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3. Why are beta-blockers contraindicated in Prinzmetal (vasospastic) angina?

• Vasodilation: via beta-2 adrenergic receptor stimulation
• Vasoconstriction: via alpha-1 adrenergic receptor stimulation

1. When beta-blockers are given, they block beta-2 receptors on coronary vessels. Beta-2 receptor activation normally causes coronary vasodilation.
2. With beta-2 receptors blocked, alpha-1 adrenergic vasoconstriction goes unopposed (alpha-mediated effects dominate).
3. This worsens coronary vasospasm and can precipitate severe or prolonged anginal attacks.
4. Additionally, the unopposed alpha effects of circulating catecholamines (especially during stress) cause greater coronary constriction.

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4. Why should liver function tests and creatine kinase be monitored during statin therapy?

• Statins reduce hepatic cholesterol synthesis; this can cause hepatocellular stress with dose-dependent elevation of liver enzymes
• Clinically significant hepatotoxicity is rare (<0.1%) but severe cases can progress to hepatic failure
• LFT monitoring: Baseline before starting; repeat if patient develops symptoms of hepatitis (jaundice, abdominal pain, dark urine); routine periodic monitoring no longer universally recommended by FDA (2012) but many centers still check
• Statins are contraindicated in active liver disease

• Statins inhibit HMG-CoA reductase which also reduces synthesis of coenzyme Q10 (ubiquinone) and other mevalonate pathway products → mitochondrial dysfunction in muscle → myocyte injury
• Myopathy spectrum: Myalgia (pain, no CK elevation) → myositis (pain + CK >3× ULN) → rhabdomyolysis (CK >10× ULN + myoglobinuria → acute tubular necrosis)
• CK should be checked at baseline and whenever patient reports muscle pain, weakness, or dark urine
• Risk factors for myopathy: High statin dose, drug interactions (CYP3A4 inhibitors - erythromycin, azole antifungals, cyclosporine), combination with fibrates (especially gemfibrozil), hypothyroidism, renal failure, elderly

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5. Why should digoxin be used cautiously in patients with hypokalemia?

1. Competition for binding site: Digoxin inhibits Na+/K+-ATPase by binding to its extracellular face, where K+ is the natural ligand (the pump normally binds extracellular K+ and pumps it inside while pumping Na+ out). Digoxin competes with K+ at this same site.
2. Hypokalemia = more digoxin binding: When serum K+ is low, there is less competition → digoxin occupies more binding sites → greater pump inhibition at the same serum digoxin level.
3. Toxicity at therapeutic levels: A patient who was previously well-controlled on a given digoxin dose can develop toxicity simply because serum K+ fell (e.g., due to furosemide or diarrhea) - without any change in the digoxin dose.
4. Worsened arrhythmias: Hypokalemia itself increases myocardial automaticity and excitability; combined with digoxin's effects (which also increase automaticity), the arrhythmia threshold is dramatically lowered.
5. Clinical relevance: In CHF, loop diuretics (furosemide) are commonly used alongside digoxin and can cause hypokalemia → always ensure adequate K+ supplementation, monitor electrolytes regularly, and consider MRA (spironolactone) to maintain K+ balance.

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6. Why are non-dihydropyridine calcium channel blockers avoided in HFrEF?

1. Negative inotropy (reduce contractility): Non-DHPs significantly decrease myocardial contractility by reducing Ca2+ influx during excitation-contraction coupling. In HFrEF (where the heart already has severely reduced contractility, EF <40%), this further depression of function can precipitate acute decompensation.
2. Negative chronotropy/dromotropy: They slow SA node firing and AV nodal conduction. In HFrEF patients who are often on beta-blockers, adding non-DHP CCBs can cause excessive bradycardia and heart block.
3. Clinical evidence: Studies have shown non-DHP CCBs increase hospitalizations and worsen outcomes in HFrEF (MDPIT study with diltiazem showed increased mortality in patients with LV dysfunction post-MI).
4. Reflex fluid retention: Vasodilation → baroreceptor activation → neurohormonal activation → sodium and water retention → worsening congestion.

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