Anti-Hypertensive Drugs

• Anti-Hypertensive Drugs is a chronic condition characterized by elevated blood pressure, increasing the risk of heart disease, stroke, and kidney disease.
• Anti-hypertensive drugs aim to lower blood pressure through various mechanisms.

Major Classes of Anti-Hypertensive Drugs:

1.Diuretics

1. Thiazide Diuretics

   • Examples: Hydrochlorothiazide, Chlorthalidone
   • MOA: Inhibit Na⁺/Cl⁻ reabsorption in the distal convoluted tubule.
   • Benefits: Reduce blood volume and peripheral resistance.
   • Side Effects: Hypokalemia, hyponatremia, hypercalcemia.

2. Loop Diuretics

   • Examples: Furosemide
   • MOA: Inhibit Na⁺/K⁺/2Cl⁻ cotransporter in the ascending loop of Henle.
   • Benefits: Potent diuresis, useful in edema.
   • Side Effects: Hypokalemia, ototoxicity.

3. Potassium-Sparing Diuretics

   • Examples: Spironolactone, Triamterene
   • MOA: Inhibit sodium channels or aldosterone receptors in the collecting ducts.
   • Benefits: Prevent hypokalemia.
   • Side Effects: Hyperkalemia, gynecomastia (spironolactone).

2. ACE Inhibitors

• Examples: Lisinopril, Ramipril
• MOA: Block conversion of angiotensin I to angiotensin II, reducing vasoconstriction and aldosterone-mediated volume retention.
• Benefits: Lower blood pressure, protect renal function in diabetes.
• Side Effects: Persistent cough, hyperkalemia, angioedema.

3. Angiotensin II Receptor Blockers (ARBs)

• Examples: Losartan, Valsartan
• MOA: Block angiotensin II type 1 receptors, preventing vasoconstriction.
• Benefits: Similar to ACE inhibitors without causing cough.
• Side Effects: Hyperkalemia, dizziness.

4. Calcium Channel Blockers

1. Dihydropyridines

   • Examples: Amlodipine
   • MOA: Predominantly vasodilatory effects by blocking L-type calcium channels in vascular smooth muscle.
   • Benefits: Lower blood pressure, treat angina.
   • Side Effects: Peripheral edema, flushing.

2. Non-Dihydropyridines

   • Examples: Diltiazem, Verapamil
   • MOA: Block calcium channels in the heart, reducing heart rate and contractility.
   • Benefits: Lower blood pressure, control arrhythmias.
   • Side Effects: Bradycardia, constipation (verapamil).

5. Beta-Blockers

• Examples: Metoprolol, Atenolol, Propranolol
• MOA: Block β-adrenergic receptors, reducing heart rate and cardiac output.
• Benefits: Lower blood pressure, reduce myocardial oxygen demand.
• Side Effects: Bradycardia, fatigue, bronchoconstriction (non-selective).
• Considerations: Caution in asthma, diabetes.

6. Alpha-Blockers

• Examples: Prazosin, Doxazosin
• MOA: Block α-adrenergic receptors, causing vasodilation.
• Benefits: Lower blood pressure.
• Side Effects: Orthostatic hypotension, dizziness.

7. Central Agonists

• Examples: Clonidine, Methyldopa
• MOA: Activate central α₂-adrenergic receptors, reducing sympathetic outflow.
• Benefits: Lower blood pressure effectively.
• Side Effects: Sedation, dry mouth, rebound hypertension upon abrupt withdrawal.

8. Renin Inhibitors

• Examples: Aliskiren
• MOA: Directly inhibit renin, decreasing angiotensin I and II production.
• Benefits: Lower blood pressure, alternative for ACE inhibitor/ARB intolerant patients.
• Side Effects: Diarrhea, hyperkalemia, renal impairment.

Clinical Considerations:

• First-Line Therapy: Often includes ACE inhibitors, ARBs, thiazide diuretics, or calcium channel blockers.
• Comorbid Conditions: Drug choice may depend on conditions like diabetes, heart failure, or chronic kidney disease.
• Lifestyle Modifications: Essential alongside pharmacotherapy (e.g., diet, exercise, smoking cessation).

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