Antihypertensive Drugs Overview

Types of Antihypertensive Drugs

The primary classes of antihypertensive medications include:

1. Diuretics (such as thiazide diuretics like hydrochlorothiazide).
2. Beta-blockers (e.g., metoprolol, atenolol).
3. ACE inhibitors (e.g., lisinopril, captopril).
4. Angiotensin II receptor blockers (ARBs) (e.g., losartan, valsartan).
5. Calcium channel blockers (e.g., amlodipine, diltiazem).
6. Alpha blockers (e.g., doxazosin, prazosin).
7. Alpha-2 receptor agonists (e.g., clonidine, methyldopa).
8. Combined alpha and beta-blockers (e.g., carvedilol, labetalol).
9. Central-acting agents (e.g., clonidine).
10. Methyldopa (used during pregnancy).
11. Renin inhibitors (e.g., aliskiren).

Mechanism of Action

1. Diuretics remove excess fluid and sodium from the body, helping lower blood pressure.
2. Beta-blockers slow down the heart rate, decrease the heart's workload, and reduce its output of blood.
3. ACE inhibitors prevent the formation of angiotensin II, a substance that constricts blood vessels, leading to increased blood pressure.
4. ARBs block the action of angiotensin II, causing blood vessels to relax and widen.
5. Calcium channel blockers prevent calcium from entering the muscle cells in blood vessels, causing them to relax and widen.
6. Alpha blockers relax blood vessels by blocking the action of norepinephrine (noradrenaline), a chemical that makes blood vessels narrow.
7. Alpha-2 receptor agonists decrease the activity of the sympathetic nervous system, which constricts blood vessels.
8. Combined alpha and beta-blockers are used for severe high blood pressure or heart failure.
9. Central-acting agents reduce the activity of the sympathetic nervous system, lowering blood pressure.
10. Renin inhibitors decrease the production of angiotensin II, causing blood vessels to relax and widen.

Common Side Effects

Each class of antihypertensive medication has potential side effects, which may include:

1. Diuretics: Frequent urination, dehydration, increased potassium loss (hypokalemia).
2. Beta-blockers: Bradycardia (slow heart rate), dizziness, fatigue, cold extremities, sleep disturbances.
3. ACE inhibitors: Hyperkalemia (increased potassium), persistent dry cough, kidney dysfunction, angioedema (severe allergic reaction).
4. ARBs: Hyperkalemia, kidney dysfunction, cough, angioedema.
5. Calcium channel blockers: Edema (swelling), headache, dizziness, palpitations.
6. Alpha blockers: Low blood pressure, dizziness, headache, fatigue, erectile dysfunction.
7. Alpha-2 receptor agonists: Dry mouth, drowsiness, dizziness, fatigue, sexual dysfunction, headache.
8. Combined alpha and beta-blockers: Low blood pressure, bradycardia, dizziness, fatigue.
9. Central-acting agents: Dry mouth, drowsiness, dizziness, sexual dysfunction.
10. Methyldopa: Drowsiness, dizziness, low blood pressure, depression.

The side effects may vary between individual medications within each class. It is essential to discuss any concerns with a healthcare professional and report side effects promptly. Dosing, frequency, and the combinations of medications prescribed should be carefully managed under medical supervision.