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08 antihypertensives upd

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  • 1. Antihypertensive AgentsCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 2. Hypertension High blood pressure • Normal: Systolic < 130 mm Hg Diastolic < 85 mm HgCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 3. Classification of Blood Pressure Category Systemic BP (mm Hg) Diastolic BP (mm Hg) Normal <130 <85 High normal 130-139 85-89 Hypertension Stage 1 140-159 90-99 Stage 2 160-169 100-109 Stage 3 180-209 110-119 Stage 4 ≥ 210 ≥ 120Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 4. Classification of Blood Pressure Primary Hypertension • Specific cause unknown • 90% of the cases • Also known as essential or idiopathic hypertension Secondary Hypertension • Cause is known (such as eclampsia of pregnancy, renal artery disease, pheochromocytoma) • 10% of the casesCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 5. Blood Pressure = CO x SVR • CO = Cardiac output • SVR = Systemic vascular resistanceCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 6. Instructors may want to insert EIC Image #69: Blood Pressure: Normal RegulationCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 7. Antihypertensive Agents • Medications used to treat hypertensionCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 8. Antihypertensive Agents: Categories • Adrenergic agents • Angiotensin-converting enzyme inhibitors • Angiotensin II receptor blockers • Calcium channel blockers • Diuretics • VasodilatorsCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 9. Antihypertensive Agents: Categories • Adrenergic Agents – Alpha1 blockers – Beta blockers (cardioselective and nonselective) – Centrally acting alpha blockers – Combined alpha-beta blockers – Peripheral-acting adrenergic agentsCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 10. Antihypertensive Agents: Mechanism of Action Adrenergic Agents Alpha1 Blockers (peripherally acting) • Block the alpha1-adrenergic receptors • The SNS is not stimulated Result: DECREASED blood pressure • Stimulation of alpha1-adrenergic receptors causes HYPERtension • Blocking alpha1-adrenergic receptors causes decreased blood pressureCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 11. Antihypertensive Agents: Adrenergic Agents Alpha1 Blockers • doxazosin (Cardura) • prazosin (Minipress) • terazosin (Hytrin)Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 12. Antihypertensive Agents: Mechanism of Action Adrenergic Agents Central-Acting Adrenergics • Stimulate alpha2-adrenergic receptors • Sympathetic outflow from the CNS is decreased Result: decreased blood pressureCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 13. Antihypertensive Agents: Adrenergic Agents Central-Acting Adrenergics • clonidine (Catapres) • methyldopa (Aldomet) (drug of choice for hypertension in pregnancy)Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 14. Antihypertensive Agents: Mechanism of Action Adrenergic Agents Adrenergic Neuronal Blockers (peripherally acting) • Inhibit release of norepinephrine • Also deplete norepinephrine stores • SNS (peripheral adrenergic nerves) is not stimulated Result: decreased blood pressureCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 15. Antihypertensive Agents: Adrenergic Agents Adrenergic Neuronal Blockers (peripherally acting) • reserpine • guanadrel (Hylorel) • guanethidine (Ismelin)Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 16. 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 diureticsCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 17. Antihypertensive Agents: Adrenergic Agents Therapeutic Uses • Central-Acting Adrenergics – Treatment of hypertension, either alone or with other agents – Usually used after other agents have failed due to side effects – Also may be used for treatment of severe dysmenorrhea, menopausal flushing, glaucoma – Clonidine is useful in the management of withdrawal symptoms in opioid- or nicotine- dependent personsCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 18. Antihypertensive Agents: Adrenergic Agents Therapeutic Uses • Adrenergic neuronal blockers (peripherally acting) – Treatment of hypertension, either alone or with other agents – Seldom used because of frequent side effectsCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 19. Antihypertensive Agents: Adrenergic Agents Side Effects Most common: dry mouth drowsiness sedation constipation Other: headaches sleep disturbances nausea rash cardiac disturbances (palpitations) HIGH INCIDENCE OF ORTHOSTATIC HYPOTENSIONCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 20. Antihypertensive Agents: Categories 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 blockerCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 21. 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 BPCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 22. Antihypertensive Agents: Mechanism of Action ACE Inhibitors • Aldosterone stimulates water and sodium resorption. • Result: increased blood volume, increased preload, and increased BCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 23. 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 pressureCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 24. Antihypertensive Agents 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 • Several other agents availableCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 25. Antihypertensive Agents: Therapeutic Uses ACE Inhibitors • Hypertension • CHF (either alone or in combination with diuretics or other agents) • Slows progression of left ventricular hypertrophy after an MI • Renal protective effects in patients with diabetes Drugs of choice in hypertensive patients with CHFCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 26. Antihypertensive Agents: 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!!Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 27. Antihypertensive Agents: Categories Angiotensin II Receptor Blockers (A II Blockers or ARBs) • Newer class • Well-tolerated • Do not cause coughingCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 28. Antihypertensive Agents: Mechanism of Action Angiotensin II Receptor Blockers • Allow angiotensin I to be converted to angiotensin II, but block the receptors that receive angiotensin II • Block vasoconstriction and release of aldosteroneCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 29. Antihypertensive Agents: Angiotensin II Receptor Blockers • losartan (Cozaar) • eposartan (Teveten) • valsartan (Diovan) • irbesartan (Avapro) • candesartan (Atacand) • telmisartan (Micardis)Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 30. Antihypertensive Agents: Therapeutic Uses Angiotensin II Receptor Blockers • Hypertension • Adjunctive agents for the treatment of CHF • May be used alone or with other agents such as diureticsCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 31. Antihypertensive Agents: Side Effects Angiotensin II Receptor Blockers • Upper respiratory infections • Headache • May cause occasional dizziness, inability to sleep, diarrhea, dyspnea, heartburn, nasal congestion, back pain, fatigueCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 32. Antihypertensive Agents: Categories Calcium Channel Blockers • Benzothiazepines • Dihydropyridines • PhenylalkylaminesCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 33. Antihypertensive Agents: Mechanism of Action 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 pressureCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 34. Antihypertensive Agents Calcium Channel Blockers • Benzothiazepines: – diltiazem (Cardizem, Dilacor) • Phenylalkamines: – verapamil (Calan, Isoptin) • Dihydropyridines: – amlodipine (Norvasc), bepridil (Vascor), nicardipine (Cardene) – nifedipine (Procardia), nimodipine (Nimotop)Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 35. Antihypertensive Agents: Therapeutic Uses Calcium Channel Blockers • Angina • Hypertension • Dysrhythmias • Migraine headachesCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 36. Antihypertensive Agents: Side Effects Calcium Channel Blockers • Cardiovascular – hypotension, palpitations, tachycardia • Gastrointestinal – constipation, nausea • Other – rash, flushing, peripheral edema, dermatitisCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 37. Antihypertensive Agents: 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 pressureCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 38. Antihypertensive Agents: Mechanism of Action Vasodilators • Directly relaxes arteriolar smooth muscle • Result: decreased systemic vascular response, decreased afterload, and PERIPHERAL VASODILATIONCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 39. Antihypertensive Agents Vasodilators • diazoxide (Hyperstat) • hydralazine HCl (Apresoline) • minoxidil (Loniten, Rogaine) • sodium nitroprusside (Nipride, Nitropress)Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 40. 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 emergenciesCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 41. 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 toxicityCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 42. 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.Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 43. 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.Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 44. 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.Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 45. 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.Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 46. 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.Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 47. 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.Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 48. 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.Copyright © 2002, 1998, Elsevier Science (USA). All rights reserved.
  • 49. 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 HgCopyright © 2002, 1998, Elsevier Science (USA). All rights reserved.