Antihypertensive

Antihypertensive medications are a class of drugs that are used to treat hypertension (high blood pressure). The goal of antihypertensive therapy is to reduce the risk of complications such as stroke, myocardial infarction, and heart failure.

Classification

Antihypertensive drugs can be classified into several categories based on their mechanism of action:

• Diuretics: These drugs help the kidneys remove excess sodium and water from the body, which helps to lower blood pressure. Examples include thiazide diuretics, loop diuretics, and potassium-sparing diuretics.
• Beta blockers: These medications reduce the heart rate and the heart's output of blood, which lowers blood pressure. Examples include propranolol, atenolol, and metoprolol.
• ACE inhibitors: Angiotensin-converting enzyme inhibitors prevent the formation of a hormone called angiotensin II, which normally causes blood vessels to narrow. Examples include enalapril, lisinopril, and ramipril.
• Angiotensin II receptor blockers (ARBs): These drugs block the action of angiotensin II, preventing blood vessel constriction. Examples include losartan, valsartan, and candesartan.
• Calcium channel blockers: These medications prevent calcium from entering the cells of the heart and blood vessel walls, leading to lower blood pressure. Examples include amlodipine, diltiazem, and verapamil.
• Alpha blockers: These drugs reduce nerve impulses that tighten blood vessels, allowing blood to flow more freely. Examples include doxazosin, prazosin, and terazosin.
• Centrally acting agents: These medications act on the central nervous system to lower blood pressure. Examples include clonidine and methyldopa.
• Vasodilators: These drugs directly relax the muscles in the blood vessel walls. Examples include hydralazine and minoxidil.

Mechanism of Action

Each class of antihypertensive drugs works through a different mechanism to lower blood pressure:

• Diuretics increase urine output, reducing blood volume.
• Beta blockers decrease heart rate and cardiac output.
• ACE inhibitors and ARBs interfere with the renin-angiotensin-aldosterone system.
• Calcium channel blockers prevent calcium from entering cells, reducing muscle contraction.
• Alpha blockers inhibit sympathetic nerve activity.
• Centrally acting agents reduce sympathetic outflow from the central nervous system.
• Vasodilators directly relax vascular smooth muscle.

Indications

Antihypertensive medications are primarily indicated for the treatment of hypertension. They may also be used in the management of other conditions such as heart failure, chronic kidney disease, and diabetes mellitus with hypertension.

Side Effects

Common side effects of antihypertensive drugs can include:

• Diuretics: Electrolyte imbalances, dehydration.
• Beta blockers: Fatigue, cold extremities, bradycardia.
• ACE inhibitors: Cough, hyperkalemia, angioedema.
• ARBs: Dizziness, hyperkalemia.
• Calcium channel blockers: Edema, constipation.
• Alpha blockers: Orthostatic hypotension, dizziness.
• Centrally acting agents: Sedation, dry mouth.
• Vasodilators: Headache, reflex tachycardia.

Monitoring and Management

Patients on antihypertensive therapy require regular monitoring to ensure effective blood pressure control and to manage any side effects. This may include:

• Regular blood pressure measurements.
• Blood tests to monitor kidney function and electrolyte levels.
• Assessment of adherence to medication.

See Also

• Hypertension
• Cardiovascular disease
• Renin-angiotensin system
• Blood pressure