Copyright © 2012, 2009, 2006, 2003 by Saunders, an imprint of Elsevier Inc. 1 Chapter 18 ADRENERGIC AGONISTS AND ADRENERGIC BLOCKERS

Copyright © 2012, 2009, 2006, 2003 by Saunders, an imprint of Elsevier Inc. 2 Adrenergic Agonists   Function of adrenergics

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

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

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

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

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

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

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

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

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

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)

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

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

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

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

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

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

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

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

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

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

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)

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.

Copyright © 2012, 2009, 2006, 2003 by Saunders, an imprint of Elsevier Inc. 25 Case Study (cont’d) Critical Thinking What drugs might cause some of these symptoms as side effects? Compare the action and side effects of alpha- and beta-adrenergic blockers.

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.

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.

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

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.