Antihypertensive Drugs

ANTIHYPERTENSIVE DRUGS Dr Deepti Patil

INTRODUCTION Anti-Hypertensive Drugs are used to control blood pressure in people whose blood pressure is too high. Blood pressure is a measurement of the force with which blood moves through the body's system of blood vessels. Treatments for high blood pressure depend on the type of hypertension.

HISTORY Antihypertensive drug therapy has been remarkably improved in the last 50 yrs. Before 1950 hardly effective and tolerated antihypertensive were available. Ganglion blockers developed in the 1950’s were effective but inconvenient. Guanethidine introduced in 1961 was an improvement on ganglion blockers.

Cont….. Antihypertensives of 1960-70 were methyldopa, β blockers, thiazide and high ceiling diuretics. In 1980-90, ACE inhibitors and calcium channel blockers are the latest Antihypertensives.

DEFINITION  Anti-Hypertensive Drugs are medicines that help lower blood pressure in people whose blood pressure is too high.  WHO-ISH guidelines have defined it to be 140mmHg systolic and 90mmHg diastolic, Though the chance of risk appears even above 120/80mmHg  For practical purpose Hypertension means, the level of BP at or above which long term hypertensive treatment reduce cardiovascular mortality.

CLASSIFICATION Diuretics

Thiazides: Hydrochlorothiazide, Chlorothalidone, Indapamide. High ceiling: Furosemide, etc K+ Sparing: Spironolactone, Amiloride.

ACE inhibitors

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

Angiotensin (AT1 Losartan, Candesartan, irbesartan, Valsartan, Telmisartan. receptor) blockers

Cont…... Calcium channel Verapamil, Diltiazem, Nifedipine, blockers Felodipine, Amlodipine, Nitrendipine, Lacidipine, etc. β Adrenergic blockers

Propranolol, Metaprolol, Atenolol, etc.

β+α Adrenergic blockers

Labetalol, Carvedilol

α Adrenergic blockers

Prazosin, Terazosin, Doxazosin, Phentolamine, Phenoxybenzamine.

Cont…. Central sympatholytics

Clonidine, Methyldopa

Vasodilators

Arteriolar: Hydralazine, Minoxidill, Diazoxide. Arteriolar+venous: Sodium nitroprusside

Reclassified BP readings BP Classification

BP(mmHg) Systolic & Diastolic

Normal

<120 and <80

Prehypertensive

120-139 and 80-89

Hypertensive stage I

140-159 and 90-99

Hypertensive stage II

≥160 and ≥ 100

Compelling Indications For Use Of Antihypertensive Drugs 1. Heart failure 2. High coronary artery disease (CAD) risk. 3. H/o MI in the past. 4. H/o stroke in the past 5. Diabetes 6. Chronic renal disease

Selection Of First Line Antihypertensive Drugs

Diuretics Standard Antihypertensive drugs Do not lower B.P in normotensives These drugs which causes a net loss of Na+ and water in urine.

Suitable for : 1. Elderly patients 2. Low renin hypertension 3. Isolated systolic hypertension 4. Obese with volume overload 5. Renal disease with Na+ retention 6. Low cost therapy

To be avoided: 1. Gout or family history of gout 2. Abnormal lipid profile 3. Pregnancy induced hypertension.

Drawbacks Hyperkelemia Carbohydrate intolerance Dyslipidemia Hyperuricaemia GIT and CNS disturbances Hearing loss (rarely)

Calcium Channel Blockers They lower the B.P by decreasing the peripheral resistance without compromising cardiac output Vasodilatation Fluid retention is insignificant. Their action is independent of patients renin status.

Suitable for : 1. Who have low renin and more arterial wall stiffness. 2. Isolated systolic hypertension 3. Physically or mentally active patients. 4. Asthma/COPD patients 5. Pregnant hypertensive

To be avoided: 1. Myocardial inadequacy, CHF 2. Conduction defect, sick sinus 3. Receiving β blockers 4. Ischemic heart disease; post MI cases 5. Left ventricular hypertrophy 6. Males with prostate enlargement 7. Gastroesophageal reflux

ACE inhibitor First choice drug in all grades of essential as well as renovascular hypertension Most patients require relatively lower doses which are well tolerated If used alone controls hypertension in about 50% of patients. If used in addition of diuretics/βblockers extends efficacy to ~90%

Suitable for : 1. 2. 3. 4. 5.

High renin cases or those on low salt diet Sexually active (relatively young) Diabetics, specially with nephropathy. Coexisting angina, post MI cases Coexisting left ventricular systolic. dysfunction or CHF & left ventricular hypertrophy. 6. Gout, PVD, dyslipidemic patients.

To be avoided: 1. Bilateral or unilateral renal artery stenosis. 2. Pregnancy 3. Hyperkelemia 4. Patient on high dose diuretic therapy 5. Preexisting dry cough (ACE inhibitor)

β Adrenergic blockers Mild anti hypertensives Used in mild to moderate cases. Their hypotensive response develops over 1-3weeks and is well sustained. Do not significantly lower BP in normotensives.

Suitable for: 1. Angina or post MI patient 2. Anxiety or tachycardia 3. Tense young patient 4. Non-obese, high renin hypertensive 5. Low cost therapy 6. Pregnancy

To be avoided: 1. 2. 3. 4. 5. 6.

Left ventricular failure, CHF Bradycardia, conduction defects Asthma, PVD Diabetic patient Abnormal lipid profile Requirement of optimum physical and mental activity.

Antihypertensives during pregnancy Hydralazine (vasodilator) Methyldopa CCB’s (discontinued before labor) Prazosin and clonidine

Antihypertensives avoided during pregnancy Diuretics ACE inhibitors Reserpine Nonselective β blockers Sod.nitroprusside

Thank you