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Chapter 18 Adrenergic Agonists and Adrenergic Blockers Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc. Adrenergic Agonists Function of adrenergics Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc. 2 Effects of Adrenergic Agonists at Receptors Alpha1 Increases cardiac contractility, vasoconstriction Dilates pupils, decreases salivary gland secretion Increases bladder & prostate contraction Alpha2 Inhibits norepinephrine release • Promotes vasodilation and decreased BP Decreases GI motility and tone Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc. 3 Effects of Adrenergic Agonists at Receptors (Cont.) Beta1 Increases cardiac contractility, heart rate Increases renin secretion, BP Beta2 Decreases GI tone and motility Bronchodilation Increases blood flow in skeletal muscles Relaxes smooth muscles of uterus Activates liver glycogenolysis • Increases blood glucose Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc. 4 Effects of Adrenergic Agonists at Receptors (Cont.) Dopaminergic–located in the renal, mesenteric, coronary, and cerebral arteries • Vasodilation Increases blood flow Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc. 5 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 Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc. 6 Classification of Adrenergic Agonists/Sympathomimetics Direct-acting Indirect-acting Epinephrine, norepinephrine Amphetamine Mixed-acting Ephedrine Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc. 7 Catecholamines Catecholamines Endogenous • Epinephrine, norepinephrine, dopamine Synthetic • Isoproterenol, dobutamine Noncatecholamines Most have longer duration of action than endogenous and synthetic • Phenylephrine, metaproterenol, albuterol Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc. 8 Epinephrine (Adrenaline) Nonselective Action Alpha1 increases the blood pressure. Beta1 increases heart rate. Beta2 promotes bronchodilation. Contraindications and caution Cardiac dysrhythmias, hypertension Hyperthyroidism Pregnancy Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc. 9 Epinephrine (Cont.) Action Inotropic Vasoconstrictor Bronchodilator Uses Anaphylaxis, anaphylactic shock Bronchospasms Cardiogenic shock, cardiac arrest Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc. 10 Epinephrine (Cont.) Side effects/adverse reactions Cardiac dysrhythmias Hypotension, flushing, reflex tachycardia Decreased renal perfusion Drug interaction Beta blockers • Decrease epinephrine action Digoxin • Causes cardiac dysrhythmias Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc. 11 Epinephrine (Cont.) Nursing interventions Monitor BP, heart rate, 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. Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc. 12 Albuterol (Proventil) Selective Uses Acts on beta2-adrenergic receptors Promotes bronchodilation Treats bronchospasm, asthma, bronchitis, COPD Caution Severe cardiac disease Hypertension, hyperthyroidism Diabetes mellitus, pregnancy Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc. 13 Albuterol (Cont.) 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 Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc. 14 Nursing Process: Adrenergic Agonist Assessment Nursing diagnosis Planning Nursing interventions Patient teaching Cultural considerations Evaluation Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc. 15 Central-Acting Alpha Agonists Clonidine (Catapres) Selective alpha2-adrenergic agonist (sympathomimetic) Used primarily to treat hypertension Methyldopa (Aldomet) Alpha-adrenergic agonist (sympathomimetic) that acts within the CNS Taken up into the brainstem neurons and converted to methylnorepinephrine, which is an alpha2-adrenergic agonist that leads to alpha2 activation Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc. 16 Side Effects: Adrenergic Agonists Hypertension Tachycardia Palpitations Restlessness Tremors Dysrhythmias Dizziness Urinary retention Nausea, vomiting Dyspnea Pulmonary edema Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc. 17 Adrenergic Blockers/Adrenergic Antagonists/Sympatholytics Block effects of adrenergic neurotransmitter Block alpha and beta receptor sites • Directly by occupying receptors • Indirectly by inhibiting release of neurotransmitters epinephrine and norepinephrine Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc. 18 Effects of Adrenergic Blockers at Receptors Alpha1 Vasodilation, decreased BP, reflex tachycardia Pupil constriction Suppresses ejaculation Reduces contraction of smooth muscles in bladder neck and prostate Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc. 19 Effects of Adrenergic Blockers at Receptors (Cont.) Beta1 Reduces cardiac contractility Decreases pulse Beta2 Bronchoconstriction Contracts uterus Inhibits glycogenolysis Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc. 20 Alpha Blockers Drugs that inhibit a response at alphaadrenergic receptor site Selective • Block alpha1 Nonselective • Block alpha1 and alpha2 Action • Promote vasodilation Use • Decrease symptoms of BPH, PVD Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc. 21 Beta-Adrenergic Blockers Beta blocker action Decrease BP and pulse Nonselective beta blockers Blocks beta1 • Decrease BP and pulse Blocks beta2 • Bronchoconstriction • Use with caution in patients with COPD Propranolol HCl (Inderal) • Uses Angina, cardiac dysrhythmias, hypertension, heart failure Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc. 22 Beta-Adrenergic Blockers (Cont.) Nonselective propranolol Contraindications • COPD Side effects/adverse reactions • 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 Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc. 23 Beta-Adrenergic Blockers (Cont.) Selective beta blockers Blocks beta1 only • Decrease BP and HR • 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 Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc. 24 Beta-Adrenergic Blockers (Cont.) Intrinsic sympathomimetic activity (ISA) Ability of certain beta blockers to bind with a beta receptor to prevent strong agonists from binding to that receptor producing complete activation Nonselective beta blockers with ISA–carteolol, carvedilol, penbutolol, and pindolol Selective blocker with ISA–acebutolol Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc. 25 Beta-Adrenergic Blockers (Cont.) Drug interactions Decreased effects with • NSAIDs Increased effects with • Prazosin, terazosin, atropine, anticholinergics Increased risk of hypoglycemia with • Insulin, sulfonylureas Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc. 26 Adrenergic Neuron Blockers Block release of norepinephrine Subdivision of adrenergic blockers Used to decrease BP Example • Reserpine (Serpalan): reduces the serotonin and catecholamine transmitters. Depletion of these neurotransmitters may lead to severe mental depression. Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc. 27 Nursing Process: Adrenergic Neuron Blockers Assessment Nursing diagnosis Planning Nursing interventions Patient teaching Cultural considerations Evaluation Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc. 28 Practice Question #1 When teaching a patient who has been prescribed metoprolol (Lopressor) about side/adverse effects, which is the highest priority teaching point? A. B. C. D. Report any complaints of stuffy nose. Instruct the patient how to take a pulse. Check for bladder distention. Warn of possible impotence and decreased libido. Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc. 29 Practice Question #2 Stimulation of which adrenergic receptor results in dilation of vessels and decrease in blood pressure? A. B. C. D. Alpha1 Alpha2 Beta1 Beta2 Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc. 30 Practice Question #3 The nurse is teaching the patient about the side effects of atenolol (Tenormin). These include A. B. C. D. pupillary constriction. blood vessel dilation. bronchospasm. tachycardia. Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc. 31 Practice Question #4 A nurse is administering epinephrine to a patient during a cardiac arrest. The primary desired action of this medication is to A. B. C. D. stimulate a heart rate. decrease cerebral blood flow. initiate respirations. increase blood flow to the kidneys. Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc. 32 Practice Question #5 A patient has been prescribed atenolol (Tenormin). To ensure safe dosing, the nurse teaches the patient to frequently assess what parameter? A. Daily weight B. Heart rate C. Urine output D. Body temperature Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc. 33 Practice Question #6 A patient is receiving dopamine (Intropin) intravenously. Which drug should the nurse have available to treat extravasation and tissue necrosis? A. Norepinephrine bitartrate (Levophed) B. Nadolol (Corgard) C. Phentolamine mesylate (Regitine) D. Clonidine (Catapres) Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc. 34