Antihypertensive Drug Mechanisms and Uses

Compare and contrast the mechanisms of action of different classes of antihypertensive drugs including, ACE inhibitors beta-blockers calcium channel blockers and diuretics., What are the indications and contraindications for each class?

Mechanisms and Use of Antihypertensive Drugs

ACE Inhibitors

• Mechanism: Block the conversion of angiotensin I to angiotensin II, reducing vasoconstriction and aldosterone secretion.
• Indications: Hypertension, heart failure, post-myocardial infarction, diabetic nephropathy.
• Contraindications: Pregnancy, history of angioedema, bilateral renal artery stenosis.
• Side Effects: Dry cough, hyperkalemia, hypotension, angioedema.

Beta-Blockers

• Mechanism: Inhibit beta-adrenergic receptors, reducing heart rate and myocardial contractility, lowering blood pressure.
• Indications: Hypertension, angina, heart failure, arrhythmias, post-myocardial infarction.
• Contraindications: Asthma, bradycardia, heart block, severe peripheral vascular disease.
• Side Effects: Fatigue, bradycardia, bronchospasm, depression, erectile dysfunction.

Calcium Channel Blockers

• Mechanism: Block calcium entry into vascular smooth muscle and the heart, reducing vascular resistance and myocardial contractility.
• Indications: Hypertension, angina, arrhythmias (non-dihydropyridines).
• Contraindications: Severe heart failure, bradycardia (for non-dihydropyridines).
• Side Effects: Peripheral edema, constipation, dizziness, hypotension.

Diuretics

• Mechanism: Increase sodium and water excretion, reducing blood volume and vascular resistance.
• Indications: Hypertension, heart failure, edema.
• Contraindications: Severe renal dysfunction, electrolyte imbalances.
• Side Effects: Hypokalemia (thiazides, loop diuretics), hyperkalemia (potassium-sparing diuretics), dehydration.

Summary

• ACE inhibitors and beta-blockers improve cardiac function and reduce mortality in heart failure.
• Calcium channel blockers are effective for isolated systolic hypertension and angina.
• Diuretics are first-line agents, especially in volume-dependent hypertension.
• Choice of drug depends on comorbidities, risk factors, and contraindications. APA