Antihypertensive Drugs – Classification

An Antihypertensive is a drug used to treat high Blood Pressure.

Introduction :-

How does Antihypertensive drugs work in the body?

Ans– Many Antihypertensive drugs have their primary action on systemic vascular resistance. Some of these drugs produce vasodilation by interfering with sympathetic adrenergic vascular tone (sympatholytics) or by blocking the formation of angiotensin II or its vascular receptors.

What is the first drug of choice for hypertension?

Ans– First-line therapy in patients over 55 should be a calcium channel blocker or a thiazide type diuretic.

For patients who are younger than 55, ACE inhibitors are the first-line drug of choice.

NOTE–

Angiotensin-converting enzyme (ACE) inhibitors are heart medications that widen, or dilate, your blood vessels. That increases the amount of blood your heart pumps and lowers blood pressure. They also raise blood flow, which helps to lower your heart’s workload.

Classification of Drugs :-

1. Diuretics=

• Thiazide: Hydrochlorothiazide, Chlorthalidone, Indapamide .
• High ceiling: Furosemide, etc.
• K+ Sparing: Spironolactone, Amiloride

2. ACE inhibitors=

• Captopril, Enalapril, Lisinopril, Perindopril, Ramipril, Fosinopril, etc.

3. Angiotensin (II receptor) blockers=

• Losartan, Candesartan, Irbesartan, Valsartan, Telmisartan

4. Direct renin inhibitor=

• Aliskiren

5. Calcium channel blockers=

• Verapamil, Diltiazem, Nifedipine, Felodipine, Amlodipine, Nitrendipine, Lacidipine, etc.

6. Beta Adrenergic blockers=

• Propranolol, Metoprolol, Atenolol, etc

7. Beta+ Alpha Adrenergic blockers=

• Labetalol, Carvedilol

8. Alpha Adrenergic blockers=

• Prazosin, Terazosin, Doxazosin Phentolamine, Phenoxybenzamine

9. Central sympatholytics=

• Clonidine, Methyldopa

10. Vasodilators=

• Arteriolar: Hydralazine, Minoxidil, Diazoxide
• Arteriolar + venous: Sodium nitroprusside

DIURETICS

Diuretics are sometimes called “water pills” because they make you pee more.

• Thiazide diuretics help treat hypertension by causing the blood vessels to widen and the body to remove any extra fluid.

Examples of thiazides include: metolazone (Zaroxolyn), indapamide (Lozol), and hydrochlorothiazide (Microzide).

Hydrochlorothiazide Lowering high blood pressure helps prevent strokes, heart attacks, and kidney problems.

chlorthalidone provides greater blood pressure lowering effects over a 24-hour period than hydrochlorothiazide.

Indapamide is used to treat high blood pressure and also heart failure.

• High ceiling Diuretics

This is the diuretic used to treat Hypertension and edema associated with heart failure, renal failure, or liver disease.

Furosemide, is a strong diuretic, but the antihypertensive efficacy does not parallel diuretic potency. Furosemide is a weaker antihypertensive than thiazides: fall in BP is entirely dependent on reduction in plasma volume.

• K+ sparing

Potassium sparing diuretics; Spironolactone, eplerenone and amiloride but not triamterene themselves lower BP slightly.

Spironolactone is not favoured because of its hormonal side effects (Impotence, Menstrual irregularities).

ANGIOTENSIN CONVERTING ENZYME (ACE) INHIBITORS

This help relax your veins and arteries to lower your blood pressure.

ACE inhibitors prevent an enzyme in your body from producing angiotensin II, a substance that narrows your blood vessels. This narrowing can cause high blood pressure and force your heart to work harder.

Captopril is used to treat high blood pressure helps prevent strokes, heart attack, and kidney problems.

It is also used to treat heart failure, protect the kidneys from harm due to diabetes, and to improve survival after a heart attack.

Fosinapril – Lowering high blood pressure helps prevent stroke, heart attack, and kidney problems. It is also used to treat heart failure.

DIRECT RENIN INHIBITOR

Aliskiren is the first in a class of drugs called direct renin inhibitors.

It is used for essential (primary) hypertension and typically recommended due to concerns of higher side effects and less evidence of benefit.

ANGIOTENSIN (II RECEPTOR) BLOCKERS

Losartan is a medication mainly used to treat high blood pressure also used for diabetic kidney disease, heart failure, and left ventricular enlargement. It is taken by mouth.

Candesartan is an angiotensin receptor blocker used mainly for the treatment of high blood pressure and congestive heart failure.

CALCIUM CHANNEL BLOCKERS

Verapamil is a medication used for the treatment of high blood pressure, angina (chest pain from not enough blood flow to the heart), and supraventricular tachycardia. It may also be used for the prevention of migraines and cluster headaches.It is given by mouth or by injection into a vein.

Diltiazem used to treat high blood pressure, angina, and certain heart arrhythmias. It may also be used in hyperthyroidism if beta blockers cannot be used. It is taken by mouth or injection into a vein.

Nifedipine is a medication used to manage angina, high blood pressure and premature labor. It is one of the treatment of choice for Prinzmetal angina. It may be used to treat severe high blood pressure in pregnancy. Its use in preterm labor may allow more time for steroids to improve the baby’s lung function . Taken by mouth.

Felodipine cure bp and angina . The only very common side effect occurring is pain and swelling in the arms and legs.

CENTRAL SYMPATHOLYTICS

Clonidine is a medication used to treat high blood pressure, attention deficit hyperactivity disorder, drug withdrawal (alcohol, opioids, or smoking), menopausal flushing, diarrhea, and certain pain conditions. It is used by mouth, by injection, or as a skin patch.

Methyldopa It is one of the preferred treatments for high blood pressure in pregnancy. Onset of effect is around 5 hours and they last about a day.

BETA ADRENERGIC BLOCKERS

Propranolol It is used to treat high blood pressure, a number of types of irregular heart rate, thyrotoxicosis, capillary hemangiomas, performance anxiety, and essential tremors. It is used to prevent migraine headaches, and to prevent further heart problems in those with angina or previous heart attacks. It can be taken by mouth or by injection into a vein.

Atenolol (Tenormin) is a beta-blocker that affects the heart and circulation (blood flow through arteries and veins). Atenolol is used to treat angina (chest pain) and hypertension (high blood pressure). Atenolol is also used to lower the risk of death after a heart attack.

Metoprolol, It is used to treat high blood pressure, chest pain due to poor blood flow to the heart, and a number of conditions involving an abnormally fast heart rate. It is also used to prevent further heart problems after myocardial infarction and to prevent headaches in those with migraines.

BETA+ ALPHA ADRENERGIC BLOCKERS

Labetalol is a medication used to treat high blood pressure and in long term management of angina.This includes essential hypertension, hypertensive emergencies, and hypertension of pregnancy. It can be given by mouth or by injection into a vein.

Carvedilol is a medication used to treat high blood pressure, congestive heart failure (CHF), and left ventricular dysfunction in people who are otherwise stable. For high blood pressure, it is generally a second-line treatment.

ALPHA ADRENERGIC BLOCKERS

Prazosin is a medication primarily used to treat high blood pressure, symptoms of an enlarged prostate, and posttraumatic stress disorder (PTSD). It is a less preferred treatment of high blood pressure.

VASODILATORs

Minoxidil It is capable of reducing blood pressure in most persons with resistant hypertension where therapy has failed with multidrug regimen. Minoxidil effect can be limited because of an increase in pulse rate or sodium (and water) retention. Thus, minoxidil is generally administered with both a diuretic and an agent that can keep pulse rate in check, such as a beta blocker or a combined alpha-beta blockers.

Diazoxide is a medication used to treat low blood sugar due to a number of specific causes.

Hydralazine is a medication use to treat high blood pressure and heart failure. This includes high blood pressure in pregnancy. It is given by mouth or by injection into a vein.Effects usually begin around 15 minutes and last up to six hours.

Sodium nitroprusside (SNP) This may be done if the blood pressure is very high and resulting in symptoms, in certain types of heart failure, and during surgery to decrease bleeding. It is used by continuous injection into a vein. effects last for up to ten minutes.