Antihypertensive Drugs Year 4 Internal Medicine Notes

Antihypertensive Drugs Year 4 · Internal Medicine Collection: 4TH YEAR ALL NOTES / IMED / I MED BEAUTIFUL NOTES / CVS -- Editing File\n\nObjectives: ● Identify the factors that control blood pressure. ● Outline the pharmacologic classes of drugs used in treatment of\nhypertension. ● Describe the mechanism of action, therapeutic uses & common adverse\neffects and contraindications of each class of drugs. ● Select the suitable antihypertensive drug to treat a specific patient\naccording to efficacy, safety, suitability & cost. \n\n❖ is a common\ncondition in which the long-term force of the blood against\nartery walls is high enough that it may eventually cause\nhealth problems. ❖ Prevalence: 25-30% of adult population,\nOnly 6% of diagnosed hypertensive patients have goal BP\neven after correct treatment. In majority of cases,\nhypertension persists for years without any symptoms, thus\ncalled “silent killer”. Eventually, it may lead to many\ncomplications including end-organ failure and death\n(Leading cause). ❖ 1. Primary (essential) Hypertension: mostly no identifiable\ncause; tends to develop gradually over years. 2. Secondary Hypertension: ● secondary to another disease (e.g., Kidney problems,\nAdrenal gland tumors, Cushing syndrome) it occurs\nsuddenly and causes higher BP than the primary. ● Drug-induced hypertension, caused by a response to\nmedication, as: A. Alcohol, cocaine, Antidepressants, Caffeine,\nCorticosteroids, Cyclosporine, Erythropoietin, Estrogens,\nNasal decongestants, NSAIDs. B. Rebound hypertension occurs when blood pressure rises\nafter you stop taking or lower the dose of a drug (typically a\nhypertension medication, e.g. clonidine). \n\n1. Lifestyle modification: Thus patients with hypertension\nshould follow some lifestyle modification, as weight loss,\nphysical activity, sodium reduction and smoking cessation. 2. Drug Therapy: Drug therapy is indicated to achieve target\nBP = 140/ 90 mm Hg (target BP for diabetics = 130/80\nmm Hg) ❖ 1. To achieve synergism (improve effects), and thus decrease\nside effects by decreasing the pharmacological individual\ndose. 2. Oppose side effects for one another. Note: drugs from the\nsame class or drugs with the same mechanism of action\nshould NOT be combined together, as they may cause\nresistance and increase side effects. \n\n …\nDrug Management of Hypertension:\nClassification of Drug Examples \nHydrochlorothiazide, Chlorthliazide\nDiuretics\nand chlorthalidone, Furosemide \nAngiotensin Losartan, valosartan, Candesatran,\nDrugs acting on receptor\nBlockers Telmisartan & irbesartan\nthe reninangiotensin\naldosterone\nsystem (RAAS)\nACE Inhibitor captopril, lisonopril, enalapril, ramipril\n\nCalcium channel blockers Verapamil, Diltiazem & Nifedipine \nHydralazine, Minoxidil, Diazoxide, &\nVasodilators\nNa-nitropruside \nβ Nadolol, Bisoprolol, Atenolol, metoprolol,\nAdrenoceptor\nBlockers propranolol, Labetalol, & carvidalol\n\n αDrugs acting on Adrenoceptor Prazosin, doxazosin & Terazosin\nsympathetic Blockers nervous system\n\n Centrally\nacting Clonidine & α methyl dopa\nsympatholytic \n\n Potassium-sparing\nGroup: Thiazides Loop diuretics\ndiuretics \nFurosemide\n•Hydro-chlorothiazide (more potent •Amiloride\n•Chlorthliazide diuresis but a •Aldosterone\nExample •chlorthalidone smaller decrease antagonists (mainly\nbest for hypertensive patients\nwith no other complications in (Pulse volume spironolactone)\nRecording) \n•hypertension minimal effect on\nwith renal lowering BP, but used\nThiazide diuretics can\nimpairment NOT in combination with\nbe used as initial drug\nthiazides loop diuretics and\nUses therapy for Mild to\n•manage thiazides to reduce\nModerate\nsymptoms of potassium loss\nhypertension\nheart failure and induced by these\nedema. diuretics \nThe initial diuresis lasts 4-6 weeks and then replaced by a\ndecrease in PVR.\nE.g. thiazide diuretics lower BP initially by increasing sodium and\nwater excretion. This causes a decrease in blood volume, Mechanism resulting in a decrease in cardiac output and renal blood flow.\nWith long-term treatment, plasma volume approaches a normal\nvalue, but a hypotensive effect persists that is related to a\ndecrease in peripheral resistance by Na+ in vessel wall then\nNa+ - Ca++ exchange which Ca++ in smooth muscle wall. \nDiuretics may be adequate in mild to moderate hypertension,\naccording to ALLHAT, chlorthalidone is superior to an ACE\nNote inhibitor, a calcium channel blocker and an alpha1- adrenergic\nantagonist in preventing one or more cardiovascular events\n(CVD). -Contra-indicated in gout & hypokalemia/hyponatremia. \n\n Captopril Lisonopril Enalapril Ramipril \n● ACE inhibitors decrease angiotensin II (vasoconstrictor) and increase bradykinin levels Mechanism\n\n (vasodilator) by preventing its degradation by ACE.\n● The antihypertensive effect of ACE inhibitors results primarily from vasodilatation\n(reduction of peripheral resistance) without reflexively increasing cardiac output