Antihypertensive drugs: Classification, Mechanism of action

Antihypertensive drugs are drugs that are used to treat hypertension( high blood pressure)

There are different types of antihypertensive drugs that work differently in order to lower elevated blood pressure.

What is blood pressure?

It is generally a force that moves blood through our circulatory system.

Oxygen and nutrients would not be able to push around our circulatory system to nourish organs and tissues without blood pressure.

What is normal Blood pressure?

The normal blood pressure is 120/80 mmHg. Which is that the normal systolic blood pressure is 120 and the normal diastolic blood pressure is 80

when the systolic blood pressure is more than 140 and the diastolic blood pressure is more than 90. Then it is said to be a high blood pressure

Classification of Hypertensive drugs

1. Diuretics	Thiazides: Hydrochlorothiazide, Chlorthalidone High ceiling diuretics: Furosemide, Torsemide k+ sparing: Spironolactone, Amiloride
2. ACE inhibitors	Captopril, Enalapril, Ramipril, Lisinopril
3. Angiotensin (AT1 receptor blockers)	Losartan, Telmisartan, Valsartan
4. β adrenergic blockers	Atenolol, Propanolol, Metoprolol
5. α+β adrenergic blockers	Labetalol, Carvedilol
6. α adrenergic blockers	Terazosin, Prazosin, Phentolamine, Phenoxybenzamine
7. Calcium channel blockers	Verapamil, Nifedipine, Amlodipine
8. Central Sympatholytics	Clonidine, Methyldopa
9. Vasodilators	-Arteriolar= Minoxidil, Diazoxide, Hydralazine -Arteriolar+Venus= Sodium nitroprusside
10. Direct renin inhibitors	Aliskiren

1. Diuretics:

Diuretics such as chlorthalidone or Hydrochlorothiazide lowers the blood pressure by increasing sodium excretion

Diuretics help your body to get rid of sodium and water. Most of the diuretics work by making your kidneys release more sodium into the urine.

The sodium then takes water with it from your blood and decreasing the amount of fluid that is flowing through the blood vessels and hence lowering the blood pressure.

2. ACE (angiotensin convertase enzyme) inhibitors

ACE inhibitors are used as a first-line treatment of hypertension in patients with a variety of indications, like high coronary disease, risk of a history of diabetes, heart failure, myocardial infarction, stroke, or chronic kidney disease.

ACE inhibitors usually work by decreases Angiotensin II and increase the level of Bradykinin. This in result causes vasodilation and hence lowering the elevated blood pressure.

Ace inhibitors reduce both cardiac preload and afterload, thereby decreasing cardiac work.

3. Angiotensin (AT1 receptor blocker)

The pharmacological effect of angiotensin(AT1 receptor blocker) is similar to those of ACE inhibitors.

The angiotensin blockers produce arteriolar and venous dilation and block aldosterone secretion, thus lowering blood pressure and decreasing salt and water retention.

4. β adrenergic blockers

Beta-blockers, which are also known as beta-adrenergic blocking agents, are the medicines that reduce blood pressure. Beta-blockers do their work of lowering the blood pressure by blocking the effects of the hormone epinephrine, which is also known as adrenaline. Beta-blockers makes your heart to beat more slowly and with less force, that helps to lowers the blood pressure

5. α+β adrenergic blockers

Alpha and beta dual receptor blockers are a subclass of beta-blockers that are commonly used to treat high blood pressure (BP). Drugs in this class include carvedilol, labetalol.

6. α adrenergic blockers

Alpha-blockers helps to lower the blood pressure by keeping the hormone norepinephrine from tightening the muscles in the walls of smaller arteries and veins.

Alpha-blockers are mainly used in combination with other antihypertensive drugs in order to treat high blood pressure.

7. Calcium channel blockers

Calcium channel blockers such as arteriesAmlodipine, Nifedipine lower your blood pressure by preventing calcium ions from entering the cells of your arteries and heart.

Calcium causes your arteries and heart to contract more strongly.

8. Central sympatholytics

Central Sympatholytics is the type of antihypertensive drugs that lower blood pressure by blocking signals from your brain to your nervous system that speed up your heart and narrow your arteries and veins.

9. Vasodilators

Vasodilators such as Minoxidil/Hydralazine are not used primarily to treat hypertension.

These vasodilators act by producing vascular smooth muscle relaxation, primarily in arteries and arterioles.

This results in a decrease in peripheral resistance.

Hydralazine and Minoxidil are the drugs used topically to treat the male pattern baldness.

10. Direct renin inhibitors

A selective renin inhibitor, Aliskiren directly inhibits renin, and thus act in the renin-angiotensin-aldosterone system, Then ACE inhibitors and then Angiotensin blockers.