Antihypertensive Drugs
Antihypertensive drugs are agents used to reduce the elevated blood pressure. They can be classified based on the mechanism of action as under:
Agents interfering with sympathetic activity
- Alpha adrenergic receptor blockers: Phentolamine, tolazoline, prazosin,
- Beta adrenergic blockers: Propranolol, Atenolol, Metoprolol
- Alpha and Beta adrenergic blocker: Labetalol
- Agents interfering with central sympathetic activity: Clonidine
Vasodilators as hypertensive drugs
- Nitrates: Amyl nitrate, isosorbide dinitrate, glyceryl trinitrate ( nitroglycerine) are used as vasodilators.
- Calcium channel blockers: Drugs under this category include verapamil, diltiazem, nifedipine, nimodipine and amlodipine.
- Potassium channel activators: Drugs under this category include cromokalin, pinacidil, minoridil and diazoxide.
- Agents that act by increasing cyclic nucleotide concentration: Nitroprusside
- Vasodilators with unknown mechanism of action: Hydralazine
- Agents acting through inhibition of Angiotensin
- Angiotensin Converting enzyme inhibtors: Enalapril, Captopril
- Angiotensin Receptor blocker: Losartan
Clinical use of Antihypertensive drugs
These drugs category used in clinics, use also described below-
- Diuretics
- ACE inhibitors / AT1 antagonists
- β -adrenergic blockers
- Calcium channel blockers
Clinical use of Diuretics as Antihypertensive drugs
- Thiazides and related drugs are drugs of choice in uncomplicated hypertension
- Thiazides are mild antihypertensives
- Effective in elderly patients
- They are effective in Isolated systolic hypertension,
- low renin hypertension
- Obese with volume overload
- They are indicated in hypertension complicated by
- Heart failure
- Risk of Coronary artery disease
- Diabetes
- Diuretics should be avoided in
- Patients with abnormal lipid profile
- Pregnancy induced hypertension
Clinical use of ACE Inhibitors/AT1 blockers as Antihypertensive drugs
- First choice drug in all grades of essential as well as renovascular hypertension
- ACE inhibitors should be avoided in
- Bilateral renal artery stenosis
- Pregnancy
- Hyperkalaemia
- Most appropriate antihypertensives in patients with
- Diabetes
- Nephropathy/chronic kidney disease
- Left ventricular hypertrophy
- Congestive heart failure
- Post Myocardial Infarction
- Gout
- Dyslipidemia
- They appear to be more effective in relatively young patients
- ACE inhibitors produce persistent cough (during the first two weeks) and dysguesia (loss of taste sensation).
Clinical use of β -blockers as Antihypertensive drugs
- Mild antihypertensive
- They are indicated as antihypertensive in patients with
- Stable heart failure
- Post myocardial infarction
- High coronary artery disease risk
- Highly suitable for
- Patients with coexisting anxiety or tachycardia
- Relatively young non-obese patients
- High renin hypertensive patients
- Migraine patients
- Pregnant individuals
- Contraindicated in
- Peripheral vascular disease
- Pulmonary disease-asthma, COPD
- Cardiac disease-Conduction defects, decompensated heart failure
- Abnormal lipid profile
Clinical use of Calcium Channel blockers as Antihypertensive drugs
- Preferred in
- Elderly hypertensive patients who have poor arterial wall compliance
- Isolated systolic hypertension
- Asthma/COPD patients
- Pregnant hypertensive
- Diabetes
- Prevents recurrent stroke
- Verapamil and diltiazem should be avoided in
- Congestive heart failure , cardiac conduction defects
- Dihydropyridines should be avoided in
- Ischaemic heart disease
- Post myocardial infarction
- Gastroesophageal reflux
- Males with prostate enlargement