Antihypertensives
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Antihypertensives

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Antihypertensives Antihypertensives Presentation Transcript

  • Antihypertensive Agents
  • Hypertension
    • High blood pressure
    • Normal: Systolic < 130 mm Hg Diastolic < 85 mm Hg
  • 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  120
  • 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 cases
  • Blood Pressure = CO x SVR
    • CO = Cardiac output
    • SVR = Systemic vascular resistance
  • Instructors may want to insert EIC Image #69: Blood Pressure: Normal Regulation
  • Antihypertensive Agents
    • Medications used to treat hypertension
  • Antihypertensive Agents: Categories
    • Adrenergic agents
    • Angiotensin-converting enzyme inhibitors
    • Angiotensin II receptor blockers
    • Calcium channel blockers
    • Diuretics
    • Vasodilators
  • Antihypertensive Agents: Categories
    • Adrenergic Agents
      • Alpha1 blockers
      • Beta blockers (cardioselective and nonselective)
      • Centrally acting alpha blockers
      • Combined alpha-beta blockers
      • Peripheral-acting adrenergic agents
  • 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 pressure
  • Antihypertensive Agents:
    • Adrenergic Agents
    • Alpha1 Blockers
    • doxazosin (Cardura)
    • prazosin (Minipress)
    • terazosin (Hytrin)
  • Antihypertensive Agents: Mechanism of Action
    • Adrenergic Agents
    • Central-Acting Adrenergics
    • Stimulate alpha2-adrenergic receptors
    • Sympathetic outflow from the CNS is decreased
      • Result: decreased blood pressure
  • Antihypertensive Agents:
    • Adrenergic Agents
    • Central-Acting Adrenergics
    • clonidine (Catapres)
    • methyldopa (Aldomet) (drug of choice for hypertension in pregnancy)
  • 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 pressure
  • Antihypertensive Agents:
    • Adrenergic Agents
    • Adrenergic Neuronal Blockers (peripherally acting)
    • reserpine
    • guanadrel (Hylorel)
    • guanethidine (Ismelin)
  • 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
  • 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 persons
  • 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 effects
  • 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 HYPOTENSION
  • 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 blocker
  • 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
  • Antihypertensive Agents: Mechanism of Action
    • ACE Inhibitors
    • Aldosterone stimulates water and sodium resorption.
    • Result: increased blood volume, increased preload, and increased B
  • 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
  • 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 available
  • 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 CHF
  • 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!!
  • Antihypertensive Agents: Categories
    • Angiotensin II Receptor Blockers (A II Blockers or ARBs)
    • Newer class
    • Well-tolerated
    • Do not cause coughing
  • 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 aldosterone
  • Antihypertensive Agents:
    • Angiotensin II Receptor Blockers
    • losartan (Cozaar)
    • eposartan (Teveten)
    • valsartan (Diovan)
    • irbesartan (Avapro)
    • candesartan (Atacand)
    • telmisartan (Micardis)
  • 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 diuretics
  • 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, fatigue
  • Antihypertensive Agents: Categories
    • Calcium Channel Blockers
    • Benzothiazepines
    • Dihydropyridines
    • Phenylalkylamines
  • 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 pressure
  • Antihypertensive Agents
    • Calcium Channel Blockers
    • Benzothiazepines:
      • diltiazem (Cardizem, Dilacor)
    • Phenylalkamines:
      • verapamil (Calan, Isoptin)
    • Dihydropyridines:
      • amlodipine (Norvasc), bepridil (Vascor), nicardipine (Cardene)
      • nifedipine (Procardia), nimodipine (Nimotop)
  • Antihypertensive Agents: Therapeutic Uses
    • Calcium Channel Blockers
    • Angina
    • Hypertension
    • Dysrhythmias
    • Migraine headaches
  • Antihypertensive Agents: Side Effects
    • Calcium Channel Blockers
    • Cardiovascular
      • hypotension, palpitations, tachycardia
    • Gastrointestinal
      • constipation, nausea
    • Other
      • rash, flushing, peripheral edema, dermatitis
  • 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 pressure
  • Antihypertensive Agents: Mechanism of Action
    • Vasodilators
    • Directly relaxes arteriolar smooth muscle
    • Result: decreased systemic vascular response, decreased afterload, and PERIPHERAL VASODILATION
  • Antihypertensive Agents
    • Vasodilators
    • diazoxide (Hyperstat)
    • hydralazine HCl (Apresoline)
    • minoxidil (Loniten, Rogaine)
    • sodium nitroprusside (Nipride, Nitropress)
  • 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
  • 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
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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