Sunday, December 12, 2010

Anti Hypertensive

1) Beta Blocker
MOA : Sympatholytic at Beta 1 & Beta 2 adrenoreceptor, inhibit NE at the synapse
Drugs : Propanolol, cardioselective Beta 1 antagonist :Metonolol, atenolol
SE : Bradycardia, bronchospasm, hallucinations, muscle weakness

2) Alpha blocker (seldom use in hypertension, use for BPH)
MOA : Alpha adrenoreceptor blocker cause vasodilatation
Drugs : Prazosin, Terazosin

3) Alpha & beta blocker (use in pre eclampsia / emergency treatment of hypertension)
MOA: Block alpha & beta adrenoreceptor & cause decrease in peripheral vascular resistance leads to reduction in BP
Drugs: Labetolol
SE : Drowsiness, bradycardia, complete heartblock, bronchoconstriction, pulmonary edema
Relative Contraindication : asthma, heart failure, any degree of heart block

MOA : vasodilator as angiotensin is potent vasoconstrictor. ACEI inhibit conversion of angiotensin 1 to angiotensin II by ACE
Drugs : Captopril, enalapril
SE : hyperkalemia, dry cough, hypotension, postural hypotension, angioedema
Contraindication : Renal artery stenosis, pregnancy, impaired renal function

5) Angiotensin receptor blocker (ARB)
MOA: AT1-receptor antagonists. Block the activation of angiotensin II AT1 receptor on vessels which directly causes vasodilatation, reduces secretion of vasopressin, reduces production and secretion of aldosterone
Drugs : losartan, valsartan, telmisartan
SE : Dizziness, headache, hyperkalemia, postural hypotension on first dose

6) Calcium channel blocker (CCB)
MOA: Block entry of calcium through calcium channel in the smooth muscle of endothelium cause it to relax & vasodilatation
Dihydropyridine (Nifedipine, amlodipine)
Nondihydropyridine (verapamil, diltiazem) --> reduce myocardial oxygen demand & reverse coronary spasm
SE: Dihydropyridine - reflex tachycardia, leg edemadizziness,headache
Non-dihydropyridine - arrythmias
CI ; can worse proteinuria in pt with nephropathy

7) Direct Vasodilator
MOA : at local level. Nitric oxide - potent vasodilator, enhance action of NO direct at vessels
Drugs : Hydralazine, Minoxidil, Na nitroprusside
SE : Hypotension, headache, Tachycardia, tachyphylaxis

8) Centrally acting drugs
MOA : affect on CNS & sympathetic NS
Drugs : clonidine - use or migraine
Methyldopa - safest to use in pregnancy
SE: dizzinessm postural hypotension

9) Diuretics
a) Thiazide (chlorothiazide, indapamide)
MOA: inh reabsorption of Na & K at distal tubule
SE : hypokalemia, metabolic alkalosis, hyperurecemia, hyperglycemia
CI : gout

b) Carbonic anhydrase Inhibitor (CAI) - acetazolamide - use for acute glaucoma
MOA : Inh reabsorption of NaHCO3- at proximal tubule
SE : hypokalemia, metabolic acidosis, hypersensitivity

c) Loop Diuretics - Furusemide, Bumetanide, Ethacrynic acid
MOA : Inh reabsorption of Na, Cl, K at THICK ASCENDING Loop of HenLe & increase renal blood flow by cortical vasodilatation
SE : hypokalemia, metabolic alkalosis, postural hypotension

d) Pottassium sparing - spironolactone
MOA : Aldosterone antagonist - inhibit action of aldosterone at distal tubule & collecting duct
SE : hyperkalemia, metabolic acidosis, gynecomastia

10) Renin inhibitor - Aliskiren
MOA : act on the Juxtaglomerular cells of kidney, which produce renin in response to decreased blood flow
SE : hyperkalemia, hypotension, angioedema

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