Antihypertensive drugs Classification

What is Hypertension

• Hypertension is the most common health disorder in the middle age group.
• Hypertension is the most important risk factor for cardiovascular mortality and morbidity.
• Hypertension means ‘ elevated blood pressure of more than 140/90 mm of Hg in the body.
• Normal blood pressure – 120/80 mm of Hg.
• Antihypertensive drugs are used to treat hypertension.

 

Hypertension classification

• Prehypertension

= systolic BP = 120 – 139 mmHg.

= Diastolic BP= 80 – 89 mmHg.

• Stage 1 hypertension

= Systolic = 140 – 159 mmHg.

= Diastolic = 90 – 99 mmHg.

• Stage 2 hypertension

= Systolic = above 160 mmHg.

= Diastolic = above 100 mmHg.

• Emergency hypertension

= Systolic = above 180 mmHg.

= Diastolic = above 120 mmHg.

• Isolated systolic hypertension

= systolic = 140 and above

= Diastolic = below 90 mmHg.

 

1. Primary hypertension-

It is idiopathic hypertension and the most common hypertension.

2. Secondary hypertension – 

Occur due to disease condition.

Antihypertensive drugs Classification:-

• Classification of antihypertensive drugs
• Blood pressure is controlled by the anatomic nervous system renin-angiotensin – Aldosterone system.
• The hypertensive drugs act on the heart, kidney, and blood vessels by influencing these systems.
• Hypertensive drugs are

1.  Beta-blockers.
2. Alpha-blockers.
3. Alpha and beta blockers
4. Calcium channel blockers
5. Central sympatholytic
6. Vasodilators
7.  Diuretics
8. ACE inhibitors
9. Angiotensin receptor blockers (ARB – inhibitors).

 

1. Beta blockers –

• It is a beta-adrenergic blocking agent that causes vasoconstriction in the blood vessels.
• Beta-blocker drugs prevent the stimulation of beta-adrenergic receptors of the sympathetic nervous system and decrease cardiac output and lead to low blood pressure.
• Drugs – Atenolol, timolol, metoprolol, propranolol, betaxolol, etc.
• Dose – 25 – 100 mg.

Uses of Beta Blocker

• To treat mild hypertension.
• Arrhythmia.
• Angina pectoris.
• Chest pain and heart attack.
• Glaucoma.
• Myocardial infarction.

Contradiction of Beta Blocker

• Asthma, COPD
• Bradycardia and cardiogenic shock
• Peripheral vascular disease
• Prinzmetal angina, heart block.

Adverse effects of Beta Blocker

• Orthostatic hypotension,
• fatigue, nausea and vomiting,
• bradycardia etc.

 

2. Alpha-blockers 

It is an adrenoceptor antagonist which prevents the stimulation of the adrenergic receptors and leads to decreased blood pressure.

Alpha bocker Drugs

• Doxazosin
• Prazosin
• Terazosin
• Alpha blocker drugs cause the blood vessels dilation there by lowering blood pressure.

Uses of alpha blocker

• Hypertension
• Benign prostatic hyperplasia
• Congestive heart failure
• Pheochromocytoma.

Contraindication of alpha blocker

• Hypersensitivity, hypotension
• Pregnancy, lactation.

 

3. Alpha beta blockers

• The combined drugs are used to treat high blood pressure.
• The drug causes vasodilation and decreases cardiac output.
• Drug – Labetalol 50 mg BD.

 

4. Calcium channel blockers –

It is a calcium channel antagonist that interferes in the movement of calcium through calcium channels.

• The drug is used to treat hypertension.

Calcium channel blocker Mechanism of action-

Calcium channel blocker drugs

↓

Block the entry of calcium ions into calcium channels

↓

Reduce intracellular calcium ions

↓

Relax vascular smooth muscles

↓

Vasodilation

↓

Decrease blood pressure.

 

• Calcium channel blocker Drugs

  • Amlodipine – 5 -10 mg OD
  • Nifedipine – 5 – 20 mg orally OD
  • Verapamil – 40 – 160 mg
  • Diltiazem – 30 – 60 mg.

 

• Amlodipine and nifedipine drugs decrease the main arterial pressure and increase the heart rate.
• Diltiazem and verapamil drugs depress the SA node and decrease the heart rate.

 

Calcium channel blocker drug uses 

• Hypertension
• Angina
• Arrhythmia

Calcium channel blocker Adverse effects

• Ankle edema, nausea, constipation.
• Hypotension, drowsiness, headache.
• Palpitation

 

5. Vasodilators drugs-

Vasodilators drugs Mechanism of action

Vasodilators drugs

↓

Relax the vascular smooth muscles

↓

Vasodilation

↓

Decrease blood pressure.

 

• Vasodilators drug name-

• Hydralazine – 25 – 50 mg TDS.
• Minoxidil.
• These drugs are directly worked on the vessel walls.
• Adverse effect – Rapid heartbeat, nausea or vomiting, edema, headache, hirsutism etc.

 

6. Central sympatholytic drugs

Central sympatholytics drugs

↓

Stimulate the A2 adrenergic receptor in the brain stem center

↓

Decrease the sympathetic nerve activity and outflow

↓

Decrease blood pressure.

 

• Drugs–
• Clonidine (Catapres) – 100 ug OD.
• Methyldopa (Aldomet) – 250 – 500 mg TDS.
• Methyldopa is a drug of choice of hypertension during pregnancy.

7. Diuretics drugs – 

The drugs are responsible for increasing urine output.

• Drugs are
• High efficacy drug = furosemide – 20 – 80 mg.
• Medium efficacy drug = hydrochlorothiazide drug

= Thiazide-like drugs.

• Low efficacy drug = spironolactone – 25 – 50 mg.

 

diuretics drug Mechanism of action –

Diuretics drugs

↓

Increase the urine output

↓

Decrease the extracellular fluid and plasma volume

↓

Decrease cardiac output

↓

Decrease blood pressure.

 

Uses Diuretics drugs

• Hypertension
• Edema and congestive heart failure.
• Acute pulmonary edema.
• Renal disease and liver cirrhosis.
• Glaucoma.

 

Contraindication of Diuretics drugs

• Gout disorder
• Diabetes patient
• Pregnant mother
• Dehydrated patient.

 

Side effects of Diuretics drugs 

• hypokalaemia
• hyperglycemia
• vertigo etc.

 

8. ACE inhibitors –

9. It is an angiotensin-converting enzyme inhibitor, which is used to treat high blood pressure and heart failure.

ACE inhibitor Mechanism of action

ACE inhibitor drugs

↓

Angiotensin – 1st is not converting into angiotensin – 2nd

↓

Decreased production of angiotensin – 2nd

↓

Decrease the sodium and water retention

↓

Cause the vasodilation

↵

• Decrease blood volume
• Decrease blood pressure
• Decrease sympathetic activity
• Decrease ventricular preload and afterload
• Inhibit vascular and cardiac hypertrophy.

 

ACE inhibitor Drugs

1. Captopril – 25 – 150 mg
2. Lisinopril – 5 – 40 mg
3. Enalapril – 2.5 – 40 mg
4. Ramipril- 1.25 – 10 mg.

Uses of ACE inhibitor-

• Hypertension
• Congestive heart failure (CHF)
• Myocardial infarction (MI)
• Diabetic nephropathy
• Treat high cardiovascular risk patients.

 

Contraindication of ACE inhibitor-

• Pregnancy
• Renal artery stenosis
• Azotaemia
• Hypotension
• Hyperkalaemia patient
• Severe stenosis of aortic and mitral valve
• History of allergy.

 

ACE inhibitor Adverse effects

• Hypotension, urticaria, cough
• Rashes, angioedema, hyperkalemia
• Proteinuria, taste change, leukopenia etc.

 

9. ARB inhibitors –

• Angiotensin receptor blocker drug.
• It has a similar effect as ACE inhibitors.
• The drug blocks the effect of angiotensin 2nd.
• The ARB inhibitor drug is prescribed if the patient cannot tolerate the ACE inhibitor drugs.

ARB inhibitors Mechanism of action-

ARB inhibitors drugs

↓

To inhibit the action of angiotensin 2

↓

Decrease sodium and water retention

↓

Vasodilation

↓

Decrease blood pressure.

ARB inhibitors Drugs 

Atacand (Candesartan) – 8mg.

Cozaar (losartan) – 25 – 50 mg.

Micardis (Telmisartan) – 20 – 80 mg.

Diovan (Valsartan) – 80 – 160 mg.

Benicar (olmesartan) – 20 – 40 mg.

 

ARB inhibitors Use- 

• Hypertension, congestive heart failure (CHF)
• Myocardial infarction (MI)
• Diabetic nephropathy.

 

ARB inhibitors Adverse effects

• Hyperkalaemia, hypotension, fainting
• Dizziness, fatigue, vomiting, diarrhoea
• Angioedema, back pain, etc.

 

Key points

• what is The most common hypertension is a – Primary hypertension
• Secondary hypertension occurs due to – Disease conditions
• Which system controls the blood pressure? – Autonomic nervous system
• Alpha and beta blockers combined drug is – Labetalol
• Drug of choice for pregnancy-induced hypertension – Methyldopa
• ACE inhibitor drug full form? – Angiotensin-converting enzymes
• ACE inhibitor drugs cause the – Decreased production of angiotensin 2nd
• Which hypertensive drugs are contraindicated in pregnancy? – ACE inhibitors
• ARB inhibitor drug full form – Angiotensin receptor blocker drug