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Antihypertensive Agents

Antihypertensive Agents. Unit six. Lecture objectives. At the end of this lecture the student well be able to: Describe how blood pressure control normally. List causes of hypertension. Give an example of drug that drugs which lower Bp through different mechanism.

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Antihypertensive Agents

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  1. Antihypertensive Agents Unit six

  2. Lecture objectives At the end of this lecture the student well be able to: • Describe how blood pressure control normally. • List causes of hypertension. • Give an example of drug that drugs which lower Bp through different mechanism. • Discuss nursing implication.

  3. Antihypertensive Agents • Medications used to treat hypertension

  4. Classification of Blood Pressure 1. Primary Hypertension Specific cause unknown, 90% of the cases, Also known as essential or idiopathic hypertension 2. Secondary Hypertension Cause is known (such as eclampsia of pregnancy, renal artery disease, pheochromocytoma) 10% of the cases

  5. Blood Pressure = CO x SVR • CO = Cardiac output • SVR = Systemic vascular resistance

  6. The blood pressure depend on • Systemic vascular resistance (sympathetic) • The output of blood from the heart (sympathetic pulse rate increase) • The volume and viscosity of the blood.( ACE, diuretics

  7. How drug can lowered blood pressure • Lower the systematic vesicular resistance • Lower COP. • Reduce blood volume • Act centrally (CNS)

  8. Antihypertensive Agents: Categories • Adrenergic agents (Sympathetic blocking agent) • Angiotensin-converting enzyme inhibitors • Calcium channel blockers • Diuretics • Vasodilators

  9. Sympathetic blocking agent • Drugs Lower the systematic vesicular resistance: Adrenergic Agents Alpha1 Blockers • doxazosin (Cardura) • prazosin (Minipress) • terazosin (Hytrin)

  10. Antihypertensive Agents: Mechanism of Action • Adrenergic Agents • Alpha1 Blockers (peripherally acting) • Block the alpha1-adrenergic receptors • Result: vasodilation , improve the flow of urine. • Stimulation of alpha1-adrenergic receptors causes hypertension

  11. Antihypertensive Agents: Adrenergic Agents • Therapeutic Uses • Alpha1 blockers (peripherally acting) • Treatment of hypertension • Relief of symptoms of BPH • Management of of severe CHF when used with cardiac glycosides and diuretics

  12. Side Effects • Most common: dry mouth drowsiness sedation constipation • Other: headaches sleep disturbances nausea rash cardiac disturbances (palpitations) • HIGH INCIDENCE OF postural HYPOTENSION

  13. Angiotensin-Converting Enzyme Inhibitors (ACE Inhibitors) • Large group of safe and effective drugs • Often used as first-line agents for CHF and hypertension • May be combined with a thiazide diuretic or calcium channel blocker

  14. Antihypertensive Agents: Mechanism of Action • ACE Inhibitors • RAAS: Renin Angiotensin-Aldosterone System When the enzyme angiotensin I is converted to angiotensin II, the result is potent vasoconstriction and stimulation of aldosterone • Result of vasoconstriction: increased systemic vascular resistance and increased afterload • Therefore, increased BP

  15. Antihypertensive Agents: Mechanism of Action • ACE Inhibitors • ACE Inhibitors block the angiotensin-converting enzyme, thus preventing the formation of angiotensin II. • Also prevent the breakdown of the vasodilating substance, bradykinin • Result: decreased systemic vascular resistance (afterload), vasodilation, and therefore, decreased blood pressure

  16. Examples ACE Inhibitors • captopril (Capoten) Short half-life, must be dosed more frequently than others • enalapril (Vasotec) The only ACE inhibitor available in oral and parenteral forms • lisinopril (Prinivil and Zestril) and quinapril (Accupril) Newer agents, long half-lives, once-a-day dosing

  17. Therapeutic Uses: ACE Inhibitors • Hypertension • CHF • Slows progression of left ventricular hypertrophy after an MI • Renal protective effects in patients with diabetes • Drugs of choice in hypertensive patients with CHF

  18. Side Effects: ACE Inhibitors • Fatigue • Dizziness • Headache • Mood changes • Impaired taste • Dry, nonproductive cough, reverses when therapy is stopped • NOTE: first-dose hypotensive effect may occur!!

  19. Calcium Channel Blockers Calcium Channel Blockers • Cause smooth muscle relaxation by blocking the binding of calcium to its receptors, preventing muscle contraction • This causes decreased peripheral smooth muscle tone, decreased systemic vascular resistance • Result: decreased blood pressure

  20. Calcium Channel Blockers • Benzothiazepines: • diltiazem (Cardizem, Dilacor) • Phenylalkamines: • verapamil (Calan, Isoptin) • Dihydropyridines: • amlodipine (Norvasc), bepridil (Vascor), nicardipine (Cardene) • nifedipine (Procardia), nimodipine (Nimotop)

  21. Therapeutic Uses Calcium Channel Blockers • Angina • Hypertension • Dysrhythmias

  22. Side Effects Calcium Channel Blockers Cardiovascular hypotension, palpitations, tachycardia Gastrointestinal constipation, nausea Other rash, flushing, peripheral edema, dermatitis

  23. Diuretics • Decrease the plasma and extracellular fluid volumes • Results: decreased preload decreased cardiac output decreased total peripheral resistance • Overall effect: decreased workload of the heart, and decreased blood pressure

  24. B blockers • By interfering SNS they certainly prevent the rise in COP, the ultimate goal of fall in blood pressure. • Decrease renin relase kidney. • Uses: • Lowering BP.

  25. Examples B blockers • Selective B blockers: • Atenolol • Esmolol • Non selective: • Propranolol • Oxprenolol • Combind alpha, B blockers • Labetalol

  26. Side effect • Asthma • Heart failure • Diabetes • Hallucination

  27. Antihypertensive Agents: Mechanism of Action Vasodilators • Directly relaxes arteriolar smooth muscle • Result: decreased systemic vascular response, decreased afterload, and PERIPHERAL VASODILATION

  28. Antihypertensive Agents Vasodilators • diazoxide (Hyperstat) • hydralazine HCl (Apresoline) • minoxidil (Loniten, Rogaine) • sodium nitroprusside (Nipride, Nitropress)

  29. Antihypertensive Agents: Therapeutic Uses Vasodilators • Treatment of hypertension • May be used in combination with other agents • Sodium nitroprusside and diazoxide IV are reserved for the management of hypertensive emergencies

  30. Antihypertensive Agents: Side Effects Vasodilators • Hydralazine: • dizziness, headache, anxiety, tachycardia, nausea and vomiting, diarrhea, anemia, dyspnea, edema, nasal congestion • Sodium nitroprusside: • bradycardia, hypotension, possible cyanide toxicity

  31. Antihypertensive Agents: Nursing Implications • Before beginning therapy, obtain a thorough health history and head-to-toe physical examination. • Assess for contraindications to specific antihypertensive agents. • Assess for conditions that require cautious use of these agents.

  32. Antihypertensive Agents: Nursing Implications • Educate patients about the importance of not missing a dose and taking the medications exactly as prescribed. • Patients should never double up on doses if a dose is missed; check with physician for instructions on what to do if a dose is missed. • Monitor BP during therapy. Instruct patients to keep a journal of regular BP checks.

  33. Antihypertensive Agents: Nursing Implications • Instruct patients that these drugs should not be stopped abruptly, as this may cause a rebound hypertensive crisis, and perhaps lead to CVA. • Oral forms should be given with meals so that absorption is more gradual and effective. • Administer IV forms with extreme caution and use an IV pump.

  34. Antihypertensive Agents: Nursing Implications • Remind patients that medications is only part of therapy. Encourage patients to watch their diet, stress level, weight, and alcohol intake. • Patients should avoid smoking and eating foods high in sodium. • Encourage supervised exercise.

  35. Antihypertensive Agents: Nursing Implications • Instruct patients to change positions slowly to avoid syncope from postural hypotension. • Patients should report unusual shortness of breath; difficulty breathing; swelling of the feet, ankles, face, or around the eyes; weight gain or loss; chest pain; palpitations; or excessive fatigue.

  36. Antihypertensive Agents: Nursing Implications • Men taking these agents may not be aware that impotence is an expected effect. This may influence compliance with drug therapy. • If patients are experiencing serious side effects, or believe that the dose or medication needs to be changed, they should contact their physician immediately.

  37. Antihypertensive Agents: Nursing Implications • Hot tubs, showers, or baths; hot weather; prolonged sitting or standing; physical exercise; and alcohol ingestion may aggravate low blood pressure, leading to fainting and injury. Patients should sit or lie down until symptoms subside. • Patients should not take any other medications, including OTC drugs, without first getting the approval of their physician.

  38. Antihypertensive Agents: Nursing Implications • Monitor for side/adverse effects (dizziness, orthostatic hypotension, fatigue) and for toxic effects. • Monitor for therapeutic effects • Blood pressure should be maintained at less than 140/90 mm Hg

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