Overview of Anti-Hypertensive Medications

Sep 2, 2024

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Anti-Hypertensive Medications Lecture Notes

Overview

  • Purpose of Lecture: Discuss anti-hypertensive medications, their categories, mechanisms of action, drugs involved, and adverse effects.
  • Support for the Lecture: Like, comment, subscribe, and check for additional resources in the description.

Categories of Anti-Hypertensive Medications

  1. Sympatholytics
  2. Diuretics
  3. Renin-Angiotensin Aldosterone Inhibitors
  4. Vasodilators

1. Sympatholytics

  • Mechanism of Action: Inhibit the sympathetic nervous system.
  • Subcategories:
    • Centrally Acting Drugs:
      • Clonidine and Alpha-Methyl Dopa
        • Clonidine: Alpha-2 agonist that reduces norepinephrine release, leading to decreased heart rate, contractility, and blood pressure. Used in withdrawal symptoms (e.g., alcohol, benzodiazepines).
        • Alpha-Methyl Dopa: Alters norepinephrine synthesis; used during pregnancy. May cause positive Coombs test.
    • Beta Blockers:
      • Cardio-selective Beta-1 Blockers:
        • Atenolol, Bisoprolol, Metoprolol, Esmolol.
        • Effects: Decrease heart rate, contractility, and blood pressure.
        • Adverse Effects: Bradycardia, hypotension, risk for cardiogenic shock, hypoglycemia awareness.
    • Alpha Blockers:
      • Examples: Prazosin, Doxazosin, Terazosin.
      • Effects: Vasodilation, decreased systemic vascular resistance, decreased preload, and blood pressure.
      • Adverse Effects: Reflex tachycardia, orthostatic hypotension.

2. Diuretics

  • Purpose: Reduce blood volume by inhibiting sodium and water retention.
  • Categories:
    • Thiazide Diuretics:
      • Examples: Hydrochlorothiazide, Chlorthalidone.
      • Mechanism: Inhibit sodium reabsorption at the distal convoluted tubule.
      • Adverse Effects: Hyponatremia, hypokalemia, metabolic alkalosis.
    • Loop Diuretics:
      • Examples: Furosemide, Bumetanide.
      • Mechanism: Inhibit sodium-potassium-chloride transporter in the ascending loop of Henle.
      • Adverse Effects: Ototoxicity, hypokalemia, hyperuricemia.
    • Aldosterone Antagonists:
      • Examples: Spironolactone, Eplerenone.
      • Mechanism: Inhibit sodium and water reabsorption by blocking aldosterone receptors.
      • Adverse Effects: Hyperkalemia, gynecomastia (Spironolactone).

3. Renin-Angiotensin Aldosterone Inhibitors

  • Mechanism: Block the renin-angiotensin-aldosterone (RAAS) system to lower blood pressure.
    • ACE Inhibitors:
      • Examples: Lisinopril, Captopril.
      • Effects: Decrease angiotensin II, leading to vasodilation and decreased blood pressure.
      • Adverse Effects: Cough (due to bradykinin), angioedema.
    • Angiotensin II Receptor Blockers (ARBs):
      • Examples: Losartan, Valsartan.
      • Effects: Block angiotensin II receptors, causing vasodilation and decreased blood pressure.
      • Adverse Effects: Generally fewer than ACE inhibitors.

4. Vasodilators

  • Mechanism: Relax blood vessels to reduce systemic vascular resistance.
  • Categories:
    • Calcium Channel Blockers:
      • Dihydropyridine: Amlodipine, Nifedipine (act mainly on arteries).
      • Non-Dihydropyridine: Diltiazem, Verapamil (affect heart rate and contractility).
    • Direct Acting Vasodilators:
      • Examples: Hydralazine, Minoxidil.
  • Nitroglycerin:
    • Effects: Mainly venodilator, but at high doses can also cause arterial dilation.

Key Points on Adverse Effects

  • Sympatholytics: Sedation (Clonidine), bradycardia (Beta blockers), hypotension, hypoglycemia unawareness.
  • Diuretics: Electrolyte imbalances (e.g., hypokalemia, hyperuricemia).
  • RAAS Inhibitors: Cough (ACE inhibitors), hyperkalemia.
  • Vasodilators: Reflex tachycardia, orthostatic hypotension (especially with Alpha blockers).

Treatment Considerations

  • Common Indications:
    • Post-MI: Beta blockers, ACE inhibitors.
    • Diabetes or CKD: ACE inhibitors, ARBs.
    • Heart Failure: Beta blockers, ACE inhibitors, diuretics.
    • Hypertensive Emergency: Nicardipine (neurological emergencies), Beta blockers (unstable angina, NSTEMI), Nitroprusside (aortic dissection).

Conclusion

The lecture covered anti-hypertensive medications, their mechanisms, and clinical indications. Understanding these concepts is crucial for effective management of hypertension and related complications.