Anti hypertensives

Anti hypertensives
ANTI-HYPERTENSIVES Dr. AMANULLA ABUL HASSAN CHENNAI
BLOOD PRESSURE • Measure of pressure exerted on the lateral wall of the blood vessels by a flowing column of blood • Has two components – Systolic – Diastolic • Normal- 120/80 mm of Hg
FACTORS INFLUENCING BP • Blood pressure = Cardiac output (CO)* Total peripheral resistance(TPR) • Cardiac output = Heart rate * Stroke volume • Stroke volume in turn depends upon the venous return and blood volume • TPR depends upon the size of the blood vessels mainly under the control of ANS • RAAS System
JNC – 8 Classification Category Systolic Diastolic Normal <120 <80 Prehypertensive 120-139 80-89 Stage 1 Hypertensive 140-159 90-99 Stage 2 Hypertensive >160 >100 Isolated Systolic Hypertension >/=140 <80
How Anti Hypertensives work? • By reducing blood volume and sodium concentration • By abolition of the sympathetic activity • By dilating the blood vessels • By inhibiting the RAAS system
ANTIHYPERTENSIVES DIURETICS SYMPATHOPLEGICS VASODILATORS RAAS INHIBITOR
DIURETICS • THIAZIDE-1st line drug in Management. – Hydrochlorthiazide- 12.5 to 50 mg – Chlorthaidone- 12.5 to 25mg – Indapamide- 1.25 to 5 mg . Longer acting • LOOP DIURETICS – Furosemide: 20 to 80 mg twice daily – Torsemide: 10 to 40 mg • POTASSIUM SPARING – Amiloride: 5 to 10 mg – Spiranolactone: 25 to 50 mg – Triamterene : 100 mg
• Initial and prolonged effect? – Initailly: Both CO and TPR reduces – Later: CO comes to normal and TPR remains low • ADR: – Hypokalemia* – Hyperglycemia* (What to do in diabetics?) – Hyperuricemia *(What to do in GOUT?)
SYMPATHOPLEGICS DRUGS DECREASING CENTRAL SYMPATHETIC OUTFLOW GANGLION BLOCKER NEURON BLOCKERS ALPHA BLOCKERS BETA BLOCKERS
CENTRAL SYMPATHETIC OUTFLOW INHIBITORS • CLONIDINE (0.1 to 0.2 mg twice daily) and ALPHA METHYL DOPA (250 to 500 mg twice daily) • Alpha 2 receptor agonists in brain • ADR: – Clonidine- Rebound Hypertension – Alpha Methyl Dopa- Hemolytic anemia • Moxonidine and Rilmenidine- Imidazoline receptors that modulate the activity of alpha 2 recpetors in brain • Better to add diuretics in prolonged use due to their sodium and water retention activity on prolonged use.
Ganglion Blockers • Nn type receptor blockers in Ganglion • Both sympathetic and parasympathetic system is blocked • Hence the side effects like Urinary retention and dry mouth • Hexamethonium and Trimethopan • Not used nowadays except in Aortic dissection
ADRENERGIC NEURON BLOCKERS • Reserpine, Guanethidine and Bretylium • Reserpine – Inhibits vesicular uptake of Adrenaline, Serotonin and Dopamine. – Serotonin- Depression and Suicidal tendencies • Guanethidine and Bretylium – Enters vesicles and displaces the Noradrenaline which in turn is metabolised – Active orally – Orthostatic hypotension – Not a first dose phenomenon.
Alpha Blockers • NON SELECTIVE: – Phenoxybenzamine: Pheochromocytoma – Phentolamine: Clonidine withdrawal – Tolazoline: Clonidine Withdrawal – Greater Tachycardia than selective • SELECTIVE: – DOC in Hypertension with BPH – First dose hypotension – Do not impair metabolism: Can be used in Diabetics, CAD and Gout – Prazosin : 0.5 to 20 mg – Terazosin: 1 to 5 mg – Doxazosin: 1 to 4 mg – Usually bed time doses
BETA BLOCKERS • Inhibition of Beta-1 receptors – Heart – JG apparatus – Brain • Usually Cardioselective drugs are used • Celiprolol, Oxeprenalol, Pindolol, Alprenolol and acebutalol • Esmolol, Atenolol, Nevibolol, Betaxolol and bisoprolol.
• Metoprolol succinate 50-100mg and tartrate 50- 100mg twice daily • Nebivolol 5-10mg • Propranolol 40-120mg twice daily • Carvedilol 6.25-25mg twice daily • Bisoprolol 5-10mg • Labetalol 100-300mg twice daily • Carvedilol and Labetalol is both alpha and beta blockers
• Not first line agents – reserve for post-MI/CHF • Cause fatigue and decreased heart rate • Adversely affect glucose metabolism • Mask hypoglycemic awareness • Non selective Beta blocker is contra-indiated in Asthmatics
Vasodilators • May be – Arteriolar: Potassium Channel openers, CCB, Dopamine agonist – Venodilator: Nitrates – Both arteriolar and Venous: Sodium nitroprussides, ARB, ACE-i, Alpha blockers.
Vasodilators Calcium Channel Blockers Potassium Channel Openers NO Releasers Dopamine Agonist
Calcium Channel Blockers Calcium Channel Blockers Phenylalkylamines Verapamil 80 to 120 mg thrice. ER- 240 to 480 mg stat Norverapamil Benzothiazipines Diltiazem180 to 360 mg Dihydropyridines Nifedipine, 30 to 90mg,Nicardipine, Amlodipine 5- 10mg etc
• Blocks L- type calcium Channels • Reducing the frequency of opening of the calcium channels and that results in Smooth muscle relaxation and depression of heart. • Dihydropyridines are also called as peripheral CCBs- Reflex tachycardia more common – Nifedipine – Amlodipine- Maximum Half life – Nicardipine- Longest acting • Parentral • DOC of hypertensive emergency – Nimodipine: Cerebroselective – Clevidipine: Ultrashort acting recently approved for Emergencies • Verapamil> Diltiazem
VERAPAMIL-WHERE AND WHERE NOT? WHERE? WHERE NOT? ANGINA SICK SINUS SYNDROME PSVT CHF HYPERTENSION ALONG WITH BETA BLOCKERS HOCM
POTASSIUM CHANNEL OPENERS • Releases potassium from smooth muscle leading to hyperpolarisation and relaxation • Mainly Arteriolar • Hydralazine 25-100mg twice daily – Drug induced lupus erythamatosis – Metabolised by acetylation* – Also a nitrate releaser- Needs intact endothelium • Minoxidil 5-10mg – Prodrug activated to minoxidil sulphate by Phase 2 reaction – Safe in CKD – Hirsuitism
NO releasers Releases NO Stimulate Guanalyl Cyclase Increases cGMP
• Sodium nitroprusside – Short acting – Continous i.v infusion in hypertensive emergency – Accumulation of cyanide and produce toxicity – Lead to hypothyroidism due to accumulation of Thiocyanate.
DOPAMINE AGONIST • FENOLDOPAM • D1 receptor agonist • Peripheral vasodilation • Suited for Patients with Renal diseases due to improved renal perfusion • ADR: – Hypokalemia – Increased intraocular pressure
RENIN INHIBITOR • Aliskiren • Remikiren • Enalkiren • Can be used orally for Chronic hypertension • Not in protocol provided by JNC
ACE INHIBITORS • Captopril • Lisinopril • Benazapril • Enalapril- 5 to 20mg • Fosinopril and quinapril 10-40mg • Ramipril 5-10mg • Trandolapril 2-8mg
Side effects • Dry cough • Angioedema • Taste Disturbance • Orthostatic Hypotension • Renal Failure* • Contraindicated: – Pregnancy – Hyperkalemia – Renal artery Stenosis
Angiotensin Receptor Blockers. • Candesartan 8-32mg • Valsartan 80-320mg • Losartan 50-100mg – Competetive antagonist of TXA2 • Olmesartan 20-40mg • Telmisartan 20-80mg • Side effects are all same as ACE-i Other than Cough and Angioedema.
Initial Drugs of Choice for Hypertension • ACE inhibitor (ACEI) • Angiotensin receptor blocker (ARB) • Thiazide diuretic • Calcium channel blocker (CCB)
• CKD irrespective of age and Race – ACEi and ARB • Black people without CKD- Thiazide and CCB
JNC 8 Strategies
Goal BP
Lifestyle changes • Smoking Cessation • Control blood glucose and lipids • Diet Eat healthy (i.e., DASH diet) Moderate alcohol consumption Reduce sodium intake to no more than 2,400 mg/day • Physical activity Moderate-to-vigorous activity 3-4 days a week averaging 40 min per session

Anti hypertensives

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