Comprehensive Pharmacology of Drugs Used in Congestive Heart Failure Management

Comprehensive Pharmacology of Drugs Used in Congestive Heart Failure Management

• 1.
  Pharmacology of DrugsUsed in Congestive Heart Failure (CHF) 1. Introduction Heart failure (HF), commonly known as congestive heart failure (CHF), is a complex clinical syndrome in which the heart is unable to pump sufficient blood to meet the metabolic demands of the body's tissues or can do so only at elevated filling pressures. Normally, the heart pumps oxygenated blood efficiently to maintain adequate tissue perfusion. In heart failure, cardiac output decreases due to impaired ventricular contraction, impaired ventricular relaxation, or both. As a compensatory response, several neurohormonal mechanisms become activated, including the sympathetic nervous system (SNS) and the renin- angiotensin-aldosterone system (RAAS). Although these mechanisms initially help maintain blood pressure and organ perfusion, chronic activation ultimately worsens heart failure by increasing preload, afterload, myocardial remodeling, and fluid retention. Heart failure is one of the leading causes of worldwide, particularly among elderly patients.
• 3.
  Heart failure isa clinical syndrome characterized by typical symptoms (breathlessness, fatigue, ankle swelling) caused by structural or functional abnormalities of the heart, resulting in reduced cardiac output and/or elevated intracardiac pressures.
• 4.
  3. Causes ofHeart Failure Coronary artery disease (CAD) Hypertension Myocardial infarction Diabetes mellitus Chronic kidney disease Congenital heart diseases Arrhythmias 4. Signs and Symptoms Dyspnea on exertion Fatigue Exercise intolerance Peripheral edema Weight gain due to fluid retention Tachycardia
• 5.
  When myocardial contractilitydecreases, ↓ Cardiac output decreases ↓ Renal perfusion decreases ↓ Activation of RAAS ↓ Sodium and water retention ↓ Increase in blood volume ↓ Increase in preload ↓ Pulmonary congestion and edema Simultaneously, ↓ Sympathetic nervous system activation ↓ Increase in heart rate ↓ Peripheral vasoconstriction ↓ Increase in afterload ↓ 5. Pathophysiology of Heart Failure
• 6.
  Class Examples Positive inotropicagents Digoxin, Dobutamine, Dopamine Diuretics Furosemide, Torsemide, Hydrochlorothiazide, Spironolactone ACE inhibitors Enalapril, Lisinopril, Ramipril Angiotensin Receptor Blockers (ARBs) Losartan, Valsartan Angiotensin Receptor- Neprilysin Inhibitor (ARNI) Sacubitril + Valsartan β-Blockers Carvedilol, Metoprolol succinate, Bisoprolol Aldosterone antagonists Spironolactone, Eplerenone Vasodilators Hydralazine + Isosorbide dinitrate SGLT2 inhibitors Dapagliflozin, Empagliflozin 6. Classification of Drugs Used in Congestive Heart Failure
• 7.
  1. Positive InotropicDrugs Definition Positive inotropic drugs increase the force of myocardial contraction, thereby improving cardiac output. A. Cardiac Glycosides (Digoxin)
• 8.
  Mechanism of Action Digoxininhibits the Na /K -ATPase pump present on cardiac ⁺ ⁺ myocytes. This inhibition causes: Increase in intracellular sodium Reduced activity of Na /Ca² exchanger ⁺ ⁺ Increase in intracellular calcium Enhanced interaction between actin and myosin Increased force of myocardial contraction Additionally, Decreases sympathetic activity Increases vagal tone Slows AV nodal conduction Reduces heart rate
• 9.
  Pharmacological Effects Cardiac: Increasedcardiac output, Reduced heart rate Improved myocardial efficiency Renal: Increased renal blood flow, Improved urine output Neurohormonal: Reduced sympathetic activation, Reduced renin secretion Therapeutic Uses: Heart failure with reduced ejection fraction (selected patients), Atrial fibrillation, Atrial flutter Adverse Effect: Nausea, Vomiting, Loss of appetite, Bradycardia, AV block, Ventricular arrhythmias, Blurred vision , Yellow-green vision (xanthopsia), Confusion Contraindications: Ventricular fibrillation, Digitalis toxicity Severe AV block without pacemaker
• 10.
  B. Dobutamine Mechanism Selective βagonist ₁ ↓ ↑ cAMP ↓ ↑ Calcium influx ↓ ↑ Myocardial contractility ↓ ↑ Cardiac output Uses: Acute heart failure, Cardiogenic shock, Stress echocardiography Side Effects: Tachycardia, Arrhythmias, Hypertension, Angina
• 11.
  2. Diuretics Mechanism Reducesodium and water retention ↓ Decrease blood volume ↓ Decrease preload ↓ Reduce pulmonary congestion Classification Loop: Furosemide Thiazide: Hydrochlorothiazide Potassium sparing: Spironolactone Therapeutic Uses: Pulmonary edema, Peripheral edema, Fluid overload Side Effects Loop: Hypokalemia, Dehydration Spironolactone: Hyperkalemia, Gynecomastia
• 12.
  3. ACE Inhibitors Examples:Enalapril, Ramipril, Lisinopril
• 13.
  Mechanism ACE inhibition ↓ ↓Angiotensin II ↓ ↓ Vasoconstriction ↓ ↓ Aldosterone secretion ↓ ↓ Sodium retention ↓ ↓ Preload ↓ ↓ Afterload ↓ Improved cardiac output ↓ Reduced ventricular remodeling Benefits:- Increase survival, Delay disease progression, Improve exercise tolerance, Reduce hospitalization Side Effects: Dry cough, Hyperkalemia, Hypotension Contraindications: Pregnancy, History of angioedema
• 14.
  4. Angiotensin ReceptorBlockers (ARBs) Examples: Losartan, Valsartan Mechanism Block AT receptors ₁ ↓ Prevent actions of angiotensin II ↓ Decrease preload and afterload Advantages No dry cough Better tolerated than ACE inhibitors
• 15.
  5. β-Blockers Examples: Carvedilol,Metoprolol succinate, Bisoprolol Mechanism Block β-adrenergic receptors Reduce heart rate Decrease myocardial oxygen demand Suppress chronic sympathetic activation Prevent ventricular remodeling Side Effects: Bradycardia, Fatigue, Hypotension, Bronchospasm Contraindications: Severe bradycardia, Cardiogenic shock, High-grade AV block without pacemaker, Severe uncontrolled asthma (for non-selective β-blockers)
• 16.
  6. Aldosterone Antagonists Examples:Spironolactone, Eplerenone Mechanism Block aldosterone receptors ↓ Increase sodium excretion ↓ Retain potassium ↓ Reduce cardiac fibrosis and remodeling Uses: HFrEF with persistent symptoms, Post-myocardial infarction with reduced ejection fraction (selected patients) Adverse Effects: Hyperkalemia, Gynecomastia (spironolactone), Menstrual irregularities (spironolactone) Contraindications: Severe renal impairment , Hyperkalemia
• 17.
  7. Vasodilators Examples: Hydralazine,Isosorbide dinitrate Mechanism Hydralazine predominantly dilates arterioles, reducing afterload. Isosorbide dinitrate predominantly dilates veins, reducing preload. Uses Alternative when ACE inhibitors/ARBs are not tolerated. Additional benefit in selected patient populations. Side Effects: Headache. Dizziness, Reflex tachycardia, Drug-induced lupus (hydralazine)
• 18.
  8. SGLT2 Inhibitors Examples:Dapagliflozin, Empagliflozin Mechanism Inhibit sodium-glucose cotransporter-2 in the proximal renal tubule, increasing urinary glucose and sodium excretion. They also reduce preload and afterload and provide cardiorenal protection. Clinical Uses Heart failure with reduced ejection fraction (with or without diabetes) Some patients with preserved ejection fraction Adverse Effects Genital fungal infections Volume depletion Rare euglycemic ketoacidosis Contraindications Severe renal impairment (agent-specific) Active diabetic ketoacidosis