NurseReview.Org - Antihypertensives Updates (pharmacology review notes)


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NurseReview.Org - Antihypertensives Updates (pharmacology review notes)

  1. 1. Antihypertensive Agents
  2. 2. Hypertension <ul><li>High blood pressure </li></ul><ul><li>Normal: Systolic < 130 mm Hg Diastolic < 85 mm Hg </li></ul>
  3. 3. Classification of Blood Pressure <ul><li>Category Systemic BP (mm Hg) Diastolic BP (mm Hg) </li></ul><ul><li>Normal <130 <85 </li></ul><ul><li>High normal 130-139 85-89 </li></ul><ul><li>Hypertension Stage 1 140-159 90-99 Stage 2 160-169 100-109 Stage 3 180-209 110-119 Stage 4  210  120 </li></ul>
  4. 4. Classification of Blood Pressure <ul><li>Primary Hypertension </li></ul><ul><li>Specific cause unknown </li></ul><ul><li>90% of the cases </li></ul><ul><li>Also known as essential or idiopathic hypertension </li></ul><ul><li>Secondary Hypertension </li></ul><ul><li>Cause is known (such as eclampsia of pregnancy, renal artery disease, pheochromocytoma) </li></ul><ul><li>10% of the cases </li></ul>
  5. 5. Blood Pressure = CO x SVR <ul><li>CO = Cardiac output </li></ul><ul><li>SVR = Systemic vascular resistance </li></ul>
  6. 6. Instructors may want to insert EIC Image #69: Blood Pressure: Normal Regulation
  7. 7. Antihypertensive Agents <ul><li>Medications used to treat hypertension </li></ul>
  8. 8. Antihypertensive Agents: Categories <ul><li>Adrenergic agents </li></ul><ul><li>Angiotensin-converting enzyme inhibitors </li></ul><ul><li>Angiotensin II receptor blockers </li></ul><ul><li>Calcium channel blockers </li></ul><ul><li>Diuretics </li></ul><ul><li>Vasodilators </li></ul>
  9. 9. Antihypertensive Agents: Categories <ul><li>Adrenergic Agents </li></ul><ul><ul><li>Alpha1 blockers </li></ul></ul><ul><ul><li>Beta blockers (cardioselective and nonselective) </li></ul></ul><ul><ul><li>Centrally acting alpha blockers </li></ul></ul><ul><ul><li>Combined alpha-beta blockers </li></ul></ul><ul><ul><li>Peripheral-acting adrenergic agents </li></ul></ul>
  10. 10. Antihypertensive Agents: Mechanism of Action <ul><li>Adrenergic Agents </li></ul><ul><li>Alpha1 Blockers (peripherally acting) </li></ul><ul><li>Block the alpha1-adrenergic receptors </li></ul><ul><li>The SNS is not stimulated </li></ul><ul><ul><li>Result: DECREASED blood pressure </li></ul></ul><ul><li>Stimulation of alpha1-adrenergic receptors causes HYPERtension </li></ul><ul><li>Blocking alpha1-adrenergic receptors causes decreased blood pressure </li></ul>
  11. 11. Antihypertensive Agents: <ul><li>Adrenergic Agents </li></ul><ul><li>Alpha1 Blockers </li></ul><ul><li>doxazosin (Cardura) </li></ul><ul><li>prazosin (Minipress) </li></ul><ul><li>terazosin (Hytrin) </li></ul>
  12. 12. Antihypertensive Agents: Mechanism of Action <ul><li>Adrenergic Agents </li></ul><ul><li>Central-Acting Adrenergics </li></ul><ul><li>Stimulate alpha2-adrenergic receptors </li></ul><ul><li>Sympathetic outflow from the CNS is decreased </li></ul><ul><ul><li>Result: decreased blood pressure </li></ul></ul>
  13. 13. Antihypertensive Agents: <ul><li>Adrenergic Agents </li></ul><ul><li>Central-Acting Adrenergics </li></ul><ul><li>clonidine (Catapres) </li></ul><ul><li>methyldopa (Aldomet) (drug of choice for hypertension in pregnancy) </li></ul>
  14. 14. Antihypertensive Agents: Mechanism of Action <ul><li>Adrenergic Agents </li></ul><ul><li>Adrenergic Neuronal Blockers (peripherally acting) </li></ul><ul><li>Inhibit release of norepinephrine </li></ul><ul><li>Also deplete norepinephrine stores </li></ul><ul><li>SNS (peripheral adrenergic nerves) is not stimulated </li></ul><ul><ul><li>Result: decreased blood pressure </li></ul></ul>
  15. 15. Antihypertensive Agents: <ul><li>Adrenergic Agents </li></ul><ul><li>Adrenergic Neuronal Blockers (peripherally acting) </li></ul><ul><li>reserpine </li></ul><ul><li>guanadrel (Hylorel) </li></ul><ul><li>guanethidine (Ismelin) </li></ul>
  16. 16. Antihypertensive Agents: Adrenergic Agents <ul><li>Therapeutic Uses </li></ul><ul><li>Alpha1 blockers (peripherally acting) </li></ul><ul><ul><li>Treatment of hypertension </li></ul></ul><ul><ul><li>Relief of symptoms of BPH </li></ul></ul><ul><ul><li>Management of of severe CHF when used with cardiac glycosides and diuretics </li></ul></ul>
  17. 17. Antihypertensive Agents: Adrenergic Agents <ul><li>Therapeutic Uses </li></ul><ul><li>Central-Acting Adrenergics </li></ul><ul><ul><li>Treatment of hypertension, either alone or with other agents </li></ul></ul><ul><ul><li>Usually used after other agents have failed due to side effects </li></ul></ul><ul><ul><li>Also may be used for treatment of severe dysmenorrhea, menopausal flushing, glaucoma </li></ul></ul><ul><ul><li>Clonidine is useful in the management of withdrawal symptoms in opioid- or nicotine-dependent persons </li></ul></ul>
  18. 18. Antihypertensive Agents: Adrenergic Agents <ul><li>Therapeutic Uses </li></ul><ul><li>Adrenergic neuronal blockers (peripherally acting) </li></ul><ul><ul><li>Treatment of hypertension, either alone or with other agents </li></ul></ul><ul><ul><li>Seldom used because of frequent side effects </li></ul></ul>
  19. 19. Antihypertensive Agents: Adrenergic Agents <ul><li>Side Effects </li></ul><ul><li>Most common: dry mouth drowsiness sedation constipation </li></ul><ul><li>Other: headaches sleep disturbances nausea rash cardiac disturbances (palpitations) </li></ul><ul><ul><li>HIGH INCIDENCE OF ORTHOSTATIC HYPOTENSION </li></ul></ul>
  20. 20. Antihypertensive Agents: Categories <ul><li>Angiotensin-Converting Enzyme Inhibitors </li></ul><ul><li>(ACE Inhibitors) </li></ul><ul><li>Large group of safe and effective drugs </li></ul><ul><li>Often used as first-line agents for CHF and hypertension </li></ul><ul><li>May be combined with a thiazide diuretic or calcium channel blocker </li></ul>
  21. 21. Antihypertensive Agents: Mechanism of Action <ul><li>ACE Inhibitors </li></ul><ul><li>RAAS: Renin Angiotensin-Aldosterone System </li></ul><ul><li>When the enzyme angiotensin I is converted to angiotensin II, the result is potent vasoconstriction and stimulation of aldosterone </li></ul><ul><li>Result of vasoconstriction: increased systemic vascular resistance and increased afterload </li></ul><ul><li>Therefore, increased BP </li></ul>
  22. 22. Antihypertensive Agents: Mechanism of Action <ul><li>ACE Inhibitors </li></ul><ul><li>Aldosterone stimulates water and sodium resorption. </li></ul><ul><li>Result: increased blood volume, increased preload, and increased B </li></ul>
  23. 23. Antihypertensive Agents: Mechanism of Action <ul><li>ACE Inhibitors </li></ul><ul><li>ACE Inhibitors block the angiotensin-converting enzyme, thus preventing the formation of angiotensin II. </li></ul><ul><li>Also prevent the breakdown of the vasodilating substance, bradykinin </li></ul><ul><ul><li>Result: decreased systemic vascular resistance (afterload), vasodilation, and therefore, decreased blood pressure </li></ul></ul>
  24. 24. Antihypertensive Agents <ul><li>ACE Inhibitors </li></ul><ul><li>captopril (Capoten) </li></ul><ul><li>Short half-life, must be dosed more frequently than others </li></ul><ul><li>enalapril (Vasotec) </li></ul><ul><li>The only ACE inhibitor available in oral and parenteral forms </li></ul><ul><li>lisinopril (Prinivil and Zestril) and quinapril (Accupril) </li></ul><ul><li>Newer agents, long half-lives, once-a-day dosing </li></ul><ul><li>Several other agents available </li></ul>
  25. 25. Antihypertensive Agents: Therapeutic Uses <ul><li>ACE Inhibitors </li></ul><ul><li>Hypertension </li></ul><ul><li>CHF (either alone or in combination with diuretics or other agents) </li></ul><ul><li>Slows progression of left ventricular hypertrophy after an MI </li></ul><ul><li>Renal protective effects in patients with diabetes </li></ul><ul><ul><li>Drugs of choice in hypertensive patients with CHF </li></ul></ul>
  26. 26. Antihypertensive Agents: Side Effects <ul><li>ACE Inhibitors </li></ul><ul><li>Fatigue Dizziness </li></ul><ul><li>Headache Mood changes </li></ul><ul><li>Impaired taste </li></ul><ul><ul><li>Dry, nonproductive cough, reverses when therapy is stopped </li></ul></ul><ul><ul><li>NOTE: first-dose hypotensive effect may occur!! </li></ul></ul>
  27. 27. Antihypertensive Agents: Categories <ul><li>Angiotensin II Receptor Blockers (A II Blockers or ARBs) </li></ul><ul><li>Newer class </li></ul><ul><li>Well-tolerated </li></ul><ul><li>Do not cause coughing </li></ul>
  28. 28. Antihypertensive Agents: Mechanism of Action <ul><li>Angiotensin II Receptor Blockers </li></ul><ul><li>Allow angiotensin I to be converted to angiotensin II, but block the receptors that receive angiotensin II </li></ul><ul><li>Block vasoconstriction and release of aldosterone </li></ul>
  29. 29. Antihypertensive Agents: <ul><li>Angiotensin II Receptor Blockers </li></ul><ul><li>losartan (Cozaar) </li></ul><ul><li>eposartan (Teveten) </li></ul><ul><li>valsartan (Diovan) </li></ul><ul><li>irbesartan (Avapro) </li></ul><ul><li>candesartan (Atacand) </li></ul><ul><li>telmisartan (Micardis) </li></ul>
  30. 30. Antihypertensive Agents: Therapeutic Uses <ul><li>Angiotensin II Receptor Blockers </li></ul><ul><li>Hypertension </li></ul><ul><li>Adjunctive agents for the treatment of CHF </li></ul><ul><li>May be used alone or with other agents such as diuretics </li></ul>
  31. 31. Antihypertensive Agents: Side Effects <ul><li>Angiotensin II Receptor Blockers </li></ul><ul><li>Upper respiratory infections </li></ul><ul><li>Headache </li></ul><ul><li>May cause occasional dizziness, inability to sleep, diarrhea, dyspnea, heartburn, nasal congestion, back pain, fatigue </li></ul>
  32. 32. Antihypertensive Agents: Categories <ul><li>Calcium Channel Blockers </li></ul><ul><li>Benzothiazepines </li></ul><ul><li>Dihydropyridines </li></ul><ul><li>Phenylalkylamines </li></ul>
  33. 33. Antihypertensive Agents: Mechanism of Action <ul><li>Calcium Channel Blockers </li></ul><ul><li>Cause smooth muscle relaxation by blocking the binding of calcium to its receptors, preventing muscle contraction </li></ul><ul><li>This causes decreased peripheral smooth muscle tone, decreased systemic vascular resistance </li></ul><ul><li>Result: decreased blood pressure </li></ul>
  34. 34. Antihypertensive Agents <ul><li>Calcium Channel Blockers </li></ul><ul><li>Benzothiazepines: </li></ul><ul><ul><li>diltiazem (Cardizem, Dilacor) </li></ul></ul><ul><li>Phenylalkamines: </li></ul><ul><ul><li>verapamil (Calan, Isoptin) </li></ul></ul><ul><li>Dihydropyridines: </li></ul><ul><ul><li>amlodipine (Norvasc), bepridil (Vascor), nicardipine (Cardene) </li></ul></ul><ul><ul><li>nifedipine (Procardia), nimodipine (Nimotop) </li></ul></ul>
  35. 35. Antihypertensive Agents: Therapeutic Uses <ul><li>Calcium Channel Blockers </li></ul><ul><li>Angina </li></ul><ul><li>Hypertension </li></ul><ul><li>Dysrhythmias </li></ul><ul><li>Migraine headaches </li></ul>
  36. 36. Antihypertensive Agents: Side Effects <ul><li>Calcium Channel Blockers </li></ul><ul><li>Cardiovascular </li></ul><ul><ul><li>hypotension, palpitations, tachycardia </li></ul></ul><ul><li>Gastrointestinal </li></ul><ul><ul><li>constipation, nausea </li></ul></ul><ul><li>Other </li></ul><ul><ul><li>rash, flushing, peripheral edema, dermatitis </li></ul></ul>
  37. 37. Antihypertensive Agents: Diuretics <ul><li>Decrease the plasma and extracellular fluid volumes </li></ul><ul><li>Results: decreased preload decreased cardiac output decreased total peripheral resistance </li></ul><ul><li>Overall effect: decreased workload of the heart, and decreased blood pressure </li></ul>
  38. 38. Antihypertensive Agents: Mechanism of Action <ul><li>Vasodilators </li></ul><ul><li>Directly relaxes arteriolar smooth muscle </li></ul><ul><li>Result: decreased systemic vascular response, decreased afterload, and PERIPHERAL VASODILATION </li></ul>
  39. 39. Antihypertensive Agents <ul><li>Vasodilators </li></ul><ul><li>diazoxide (Hyperstat) </li></ul><ul><li>hydralazine HCl (Apresoline) </li></ul><ul><li>minoxidil (Loniten, Rogaine) </li></ul><ul><li>sodium nitroprusside (Nipride, Nitropress) </li></ul>
  40. 40. Antihypertensive Agents: Therapeutic Uses <ul><li>Vasodilators </li></ul><ul><li>Treatment of hypertension </li></ul><ul><li>May be used in combination with other agents </li></ul><ul><li>Sodium nitroprusside and diazoxide IV are reserved for the management of hypertensive emergencies </li></ul>
  41. 41. Antihypertensive Agents: Side Effects <ul><li>Vasodilators </li></ul><ul><li>Hydralazine: </li></ul><ul><ul><li>dizziness, headache, anxiety, tachycardia, nausea and vomiting, diarrhea, anemia, dyspnea, edema, nasal congestion </li></ul></ul><ul><li>Sodium nitroprusside: </li></ul><ul><ul><li>bradycardia, hypotension, possible cyanide toxicity </li></ul></ul>
  42. 42. Antihypertensive Agents: Nursing Implications <ul><li>Before beginning therapy, obtain a thorough health history and head-to-toe physical examination. </li></ul><ul><li>Assess for contraindications to specific antihypertensive agents. </li></ul><ul><li>Assess for conditions that require cautious use of these agents. </li></ul>
  43. 43. Antihypertensive Agents: Nursing Implications <ul><li>Educate patients about the importance of not missing a dose and taking the medications exactly as prescribed. </li></ul><ul><li>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. </li></ul><ul><li>Monitor BP during therapy. Instruct patients to keep a journal of regular BP checks. </li></ul>
  44. 44. Antihypertensive Agents: Nursing Implications <ul><li>Instruct patients that these drugs should not be stopped abruptly, as this may cause a rebound hypertensive crisis, and perhaps lead to CVA. </li></ul><ul><li>Oral forms should be given with meals so that absorption is more gradual and effective. </li></ul><ul><li>Administer IV forms with extreme caution and use an IV pump. </li></ul>
  45. 45. Antihypertensive Agents: Nursing Implications <ul><li>Remind patients that medications is only part of therapy. Encourage patients to watch their diet, stress level, weight, and alcohol intake. </li></ul><ul><li>Patients should avoid smoking and eating foods high in sodium. </li></ul><ul><li>Encourage supervised exercise. </li></ul>
  46. 46. Antihypertensive Agents: Nursing Implications <ul><li>Instruct patients to change positions slowly to avoid syncope from postural hypotension. </li></ul><ul><li>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. </li></ul>
  47. 47. Antihypertensive Agents: Nursing Implications <ul><li>Men taking these agents may not be aware that impotence is an expected effect. This may influence compliance with drug therapy. </li></ul><ul><li>If patients are experiencing serious side effects, or believe that the dose or medication needs to be changed, they should contact their physician immediately. </li></ul>
  48. 48. Antihypertensive Agents: Nursing Implications <ul><li>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. </li></ul><ul><li>Patients should not take any other medications, including OTC drugs, without first getting the approval of their physician. </li></ul>
  49. 49. Antihypertensive Agents: Nursing Implications <ul><li>Monitor for side/adverse effects (dizziness, orthostatic hypotension, fatigue) and for toxic effects. </li></ul><ul><li>Monitor for therapeutic effects </li></ul><ul><li>Blood pressure should be maintained at less than 140/90 mm Hg </li></ul>