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Copyright © 2012, 2009, 2006, 2003 by Saunders, an imprint of Elsevier Inc. 1 Chapter 18 ADRENERGIC AGONISTS AND ADRENERGIC BLOCKERS
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Copyright © 2012, 2009, 2006, 2003 by Saunders, an imprint of Elsevier Inc. 2 Adrenergic Agonists Function of adrenergics
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Copyright © 2012, 2009, 2006, 2003 by Saunders, an imprint of Elsevier Inc. 3 Adrenergic Agonists (cont’d) Effects of adrenergic receptor sites Alpha 1 Increases cardiac contractility, vasoconstriction Dilates pupils, decrease salivary gland secretion Increase bladder & prostate contraction Alpha 2 Inhibits norepinephrine release Promote vasodilation and decreased BP Decrease GI motility and tone
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Copyright © 2012, 2009, 2006, 2003 by Saunders, an imprint of Elsevier Inc. 4 Adrenergic Agonists (cont’d) Effects of adrenergic receptor sites Beta 1 Increases cardiac contractility, heart rate Increases renin secretion, BP Beta 2 Decreases GI tone and motility Bronchodilation Increases blood flow in skeletal muscles Relaxes smooth muscles of uterus Activates liver glycogenolysis Increases blood glucose
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Copyright © 2012, 2009, 2006, 2003 by Saunders, an imprint of Elsevier Inc. 5 Adrenergic Agonists (cont’d) Effects of adrenergic receptor sites Dopaminergic Vasodilation Increases blood flow
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Copyright © 2012, 2009, 2006, 2003 by Saunders, an imprint of Elsevier Inc. 6 Neurotransmitter Inactivation Inactivation Reuptake of transmitter back into neuron Enzymatic transformation or degradation MAO inside neuron COMT outside neuron Diffusion away from the receptor Drugs halt termination of neurotransmitter by inhibiting Norepinephrine reuptake Norepinephrine degradation
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Copyright © 2012, 2009, 2006, 2003 by Saunders, an imprint of Elsevier Inc. 7 Classification of Adrenergic Agonists/Sympathomimetics Direct-acting Epinephrine, norepinephrine Indirect-acting Amphetamine Mixed-acting Ephedrine
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Copyright © 2012, 2009, 2006, 2003 by Saunders, an imprint of Elsevier Inc. 8 Catecholamines Catecholamines Endogenous Epinephrine, norepinephrine, dopamine Synthetic Isoproterenol, dobutamine Noncatecholamines Most have longer duration of action than endogenous and synthetic Phenylephrine, metaproterenol, albuterol
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Copyright © 2012, 2009, 2006, 2003 by Saunders, an imprint of Elsevier Inc. 9 Epinephrine (Adrenalin) Nonselective Action Alpha 1 increases the blood pressure Beta 1 increases heart rate Beta 2 promotes bronchodilation Contraindications and caution Cardiac dysrhythmias, hypertension Hyperthyroidism Pregnancy
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Copyright © 2012, 2009, 2006, 2003 by Saunders, an imprint of Elsevier Inc. 10 Epinephrine Action Inotropic Vasoconstrictor Bronchodilator Uses Anaphylaxis, anaphylactic shock Bronchospasms Cardiogenic shock, cardiac arrest
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Copyright © 2012, 2009, 2006, 2003 by Saunders, an imprint of Elsevier Inc. 11 Epinephrine (cont’d) Side effects/adverse reactions Cardiac dysrhythmias Hypotension, flushing, reflex tachycardia Decrease renal perfusion Drug interaction Beta-blockers Decreases epinephrine action Digoxin Causes cardiac dysrhythmias
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Copyright © 2012, 2009, 2006, 2003 by Saunders, an imprint of Elsevier Inc. 12 Nursing interventions Monitor BP, P, urine output. Report tachycardia, palpitations, tremors, dizziness, hypertension. Monitor IV site for infiltration. Antidote: phentolamine mesylate (Regitine) Avoid cold medicines and diet pills if hypertensive, diabetic, CAD, or dysrhythmic. Avoid adrenergics when breastfeeding. Avoid continuous use of adrenergic nasal sprays. Epinephrine (cont’d)
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Copyright © 2012, 2009, 2006, 2003 by Saunders, an imprint of Elsevier Inc. 13 Albuterol (Proventil) Selective Acts on beta 2 -adrenergic receptors Promotes bronchodilation Uses Treats bronchospasm, asthma, bronchitis, COPD Caution Severe cardiac disease Hypertension, hyperthyroidism Diabetes mellitus, pregnancy
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Copyright © 2012, 2009, 2006, 2003 by Saunders, an imprint of Elsevier Inc. 14 Albuterol Side effects/adverse reactions Tremors, nervousness, restlessness Dizziness, reflex tachycardia Hallucinations Cardiac dysrhythmias Drug interaction May increase effect with other sympathomimetics, MAO inhibitors, and tricyclic antidepressants Antagonize effect with beta blockers
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Copyright © 2012, 2009, 2006, 2003 by Saunders, an imprint of Elsevier Inc. 15 Adrenergic Blockers Block effects of adrenergic neurotransmitter Block alpha and beta receptor sites Directly by occupying receptors Indirectly by inhibiting release of neurotransmitters epinephrine and norepinephrine
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Copyright © 2012, 2009, 2006, 2003 by Saunders, an imprint of Elsevier Inc. 16 Effects of Adrenergic Blockers at Receptors Alpha 1 Vasodilation, decreased BP, reflex tachycardia Pupil constriction Suppresses ejaculation Reduces contraction of smooth muscles in bladder neck and prostate
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Copyright © 2012, 2009, 2006, 2003 by Saunders, an imprint of Elsevier Inc. 17 Effects of Adrenergic Blockers at Receptors (cont’d) Beta 1 Reduces cardiac contractility Decreases pulse Beta 2 Bronchoconstriction Contracts uterus Inhibits glycogenolysis
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Copyright © 2012, 2009, 2006, 2003 by Saunders, an imprint of Elsevier Inc. 18 Alpha Blockers Drugs that inhibit a response at alpha- adrenergic receptor site Selective Block alpha 1 Nonselective Block alpha 1 and alpha 2 Action Promote vasodilation Use Decrease symptoms of BPH, PVD
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Copyright © 2012, 2009, 2006, 2003 by Saunders, an imprint of Elsevier Inc. 19 Beta-Adrenergic Blockers Beta-blockers action Decrease BP and P Nonselective beta blockers Blocks beta 1 Decrease BP and P Blocks beta 2 Bronchostriction Propranolol HCl (Inderal) Uses Angina, cardiac dysrhythmias, hypertension, heart failure
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Copyright © 2012, 2009, 2006, 2003 by Saunders, an imprint of Elsevier Inc. 20 Beta-Adrenergic Blockers (cont’d) Nonselective propranolol Contraindications COPD SE/AR Weight gain, impotence, decreased libido, reversible alopecia Drug interactions Decreased drug effects with Phenytoin, isoproterenol, NSAIDs, barbiturates, caffeine, theophylline Heart block may occur with Digoxin, calcium channel blockers
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Copyright © 2012, 2009, 2006, 2003 by Saunders, an imprint of Elsevier Inc. 21 Beta-Adrenergic Blockers (cont’d) Selective beta blockers Blocks beta 1 only Decrease BP and P Fewer side effects Metoprolol (Lopressor), atenolol (Tenormin) Side effects/adverse reactions Bradycardia, hypotension, dysrhythmias, headaches, dizziness, fainting, fatigue, mental depression, nausea, vomiting, diarrhea, blood dyscrasias, hypoglycemia
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Copyright © 2012, 2009, 2006, 2003 by Saunders, an imprint of Elsevier Inc. 22 Beta-Adrenergic Blockers (cont’d) Drug interactions Decreased effects with: NSAIDs Increased effects with: Prazosin, terazosin, atropine, anticholinergics Increased risk of hypoglycemia with: Insulin, sulfonylureas
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Copyright © 2012, 2009, 2006, 2003 by Saunders, an imprint of Elsevier Inc. 23 Adrenergic Neuron Blockers Block release of norepinephrine Subdivision of adrenergic blockers Use Decrease BP Example Reserpine (Serpalan)
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Copyright © 2012, 2009, 2006, 2003 by Saunders, an imprint of Elsevier Inc. 24 Case Study A client visiting the outpatient health clinic complains of dizziness when standing, fatigue, severe headache, and depression. Assessment reveals a heart rate of 55 and blood pressure of 110/70. The client has a history of hypertension and is taking an antihypertensive.
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Copyright © 2012, 2009, 2006, 2003 by Saunders, an imprint of Elsevier Inc. 25 Case Study (cont’d) Critical Thinking 1. 1. What drugs might cause some of these symptoms as side effects? 2. 2. Compare the action and side effects of alpha- and beta-adrenergic blockers.
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Copyright © 2012, 2009, 2006, 2003 by Saunders, an imprint of Elsevier Inc. 26 Practice Question #1 The nurse is teaching a client who is taking metoprolol (Lopressor). Which should the nurse consider the highest priority in teaching side effects/adverse effects? A. Report any complaints of stuffy nose. B. Instruct the client how to take a pulse. C. Check urine output and bladder distention. D. Warn of possible impotence and decreased libido.
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Copyright © 2012, 2009, 2006, 2003 by Saunders, an imprint of Elsevier Inc. 27 Practice Question #1 (cont’d) Answer: B Rationale: It is most important for the client to learn how to monitor the heart rate because of the side effect of bradycardia with metoprolol.
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Copyright © 2012, 2009, 2006, 2003 by Saunders, an imprint of Elsevier Inc. 28 Practice Question #2 Which drug should the nurse realize may interact with propranolol (Inderal)? A. Antacid B. Phenytoin C. Phentolamine D. Tricyclic antidepressant
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Copyright © 2012, 2009, 2006, 2003 by Saunders, an imprint of Elsevier Inc. 29 Practice Question #2 (cont’d) Answer: B Rationale: Drug that interact with metoprolol include phenytoin, isoproterenol, NSAIDs, barbiturates, caffeine, and theophylline, which decrease propranolol’s effects. The other choices (A, C, and D) are not drugs that interact with metoprolol.
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