Jawaharlal Nehru Technological University Hyderabad B. Pharmacy III Year PHARMACOLOGY - II Previous Question Paper (February-2022 - R17)

Congestive Heart Failure (CHF) is a clinical syndrome resulting from any structural or functional cardiac disorder that impairs the ability of the ventricle to fill with or eject blood, leading to inadequate tissue perfusion. Hypertension is defined as a persistent elevation of systemic arterial blood pressure, typically exceeding 140/90 mmHg, which increases the workload on the heart and damages vascular endothelium.

Drugs used in the management of these conditions include:

• Diuretics: Drugs like furosemide and thiazides reduce blood volume and venous return, alleviating pulmonary congestion in CHF and lowering peripheral resistance in hypertension.
• RAAS Inhibitors: ACE inhibitors (e.g., enalapril) and Angiotensin Receptor Blockers (e.g., losartan) inhibit the renin-angiotensin-aldosterone system, reducing both preload and afterload, and preventing cardiac remodeling.
• Beta-Blockers: Agents such as metoprolol or carvedilol reduce sympathetic drive, decrease heart rate, and improve long-term survival in chronic heart failure while effectively lowering blood pressure.
• Vasodilators: Hydralazine and nitrates reduce systemic vascular resistance and venous return, respectively, decreasing the cardiac workload.
• Inotropic Agents: Digoxin increases myocardial contractility by inhibiting the Na+/K+-ATPase pump, which is specifically beneficial in systolic heart failure.
• Calcium Channel Blockers: Primarily used in hypertension, these agents (e.g., amlodipine) induce vasodilation by preventing calcium influx into vascular smooth muscle cells.
• Aldosterone Antagonists: Spironolactone prevents the deleterious effects of aldosterone on the myocardium, reducing fibrosis and mortality in heart failure patients.

Anti-arrhythmic drugs are classified based on the Vaughan Williams classification system, which categorizes them according to their primary electrophysiological effects on the cardiac action potential.

Class I: Sodium Channel Blockers

1. Class IA (e.g., Quinidine, Procainamide): Moderate blockade of Na+ channels, slows conduction, and prolongs repolarization. Used for atrial and ventricular arrhythmias. Adverse effects include cinchonism (quinidine), lupus-like syndrome (procainamide), and QT prolongation.
2. Class IB (e.g., Lidocaine, Mexiletine): Weak blockade of Na+ channels, shortens repolarization. Primarily used for ventricular arrhythmias, especially post-myocardial infarction. Adverse effects include CNS disturbances like dizziness and paresthesia.
3. Class IC (e.g., Flecainide, Propafenone): Potent blockade of Na+ channels, significantly slows conduction with little effect on repolarization. Used for refractory supraventricular arrhythmias. Adverse effects include pro-arrhythmic effects and blurred vision.

Class II: Beta-Adrenergic Blockers (e.g., Propranolol, Metoprolol)

These drugs reduce sympathetic activity on the heart, decreasing SA node automaticity and AV node conduction velocity. They are used for supraventricular tachycardias and to prevent sudden cardiac death post-MI. Adverse effects include bradycardia, bronchospasm, and fatigue.

Class III: Potassium Channel Blockers (e.g., Amiodarone, Sotalol)

These agents block K+ channels, thereby prolonging the action potential duration and effective refractory period. Amiodarone is a broad-spectrum agent used for both atrial and ventricular arrhythmias. Adverse effects include pulmonary fibrosis, thyroid dysfunction (hypo/hyperthyroidism), corneal deposits, and photosensitivity.

Class IV: Calcium Channel Blockers (e.g., Verapamil, Diltiazem)

These drugs block L-type Ca2+ channels in the SA and AV nodes, slowing AV nodal conduction. They are indicated for supraventricular tachycardias. Adverse effects include constipation, peripheral edema, and hypotension.

Miscellaneous Agents: Digoxin (increases vagal tone), Adenosine (transiently blocks AV node conduction for paroxysmal supraventricular tachycardia), and Magnesium sulfate (used for Torsades de pointes).