Antihypertensive Drugs

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
  1. Alpha adrenergic receptor blockers: Phentolamine, tolazoline, prazosin,
  2. Beta adrenergic blockers: Propranolol, Atenolol, Metoprolol
  3. Alpha and Beta adrenergic blocker: Labetalol
  4. Agents interfering with central sympathetic activity: Clonidine
Vasodilators as hypertensive drugs
  1. Nitrates: Amyl nitrate, isosorbide dinitrate, glyceryl trinitrate ( nitroglycerine) are used as vasodilators.  
  2. Calcium channel blockers: Drugs under this category include verapamil, diltiazem, nifedipine, nimodipine and amlodipine.
  3. Potassium channel activators: Drugs under this category include cromokalin, pinacidil, minoridil and diazoxide.
  4. Agents that act by increasing cyclic nucleotide concentration:  Nitroprusside
  5. Vasodilators with unknown mechanism of action: Hydralazine
  6. 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-

  1. Diuretics
  2. ACE inhibitors / AT1 antagonists
  3. β -adrenergic blockers
  4. 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
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