Adrenergic Agonists and Adrenergic Blockers 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 Sympathetic responses Stimulation of sympathetic nervous system or use of adrenergic drugs can cause dilation of pupils and bronchioles; increased heart rate; constriction of blood vessels; relaxation of muscles in GI tract, bladder, and uterus. Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.

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.

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.

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.

Neurotransmitter 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 After the transmitter (i.e., norepinephrine) has performed its function, the action must be stopped to prevent prolonging the effect. Two enzymes that inactivate the metabolism of norepinephrine are monoamine oxidase (MAO) and catechol-O-methyltransferase (COMT). Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.

Classification of Adrenergic Agonists/Sympathomimetics Direct-acting Epinephrine, norepinephrine Indirect-acting Amphetamine Mixed-acting Ephedrine Direct-acting sympathomimetics: directly stimulate adrenergic receptor Indirect-acting sympathomimetics: stimulate release of norepinephrine from terminal nerve endings Mixed-acting sympathomimetics: stimulate adrenergic receptor sites and stimulate release of norepinephrine from terminal nerve endings Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.

Catecholamines Catecholamines Noncatecholamines Endogenous Synthetic Epinephrine, norepinephrine, dopamine Synthetic Isoproterenol, dobutamine Noncatecholamines Most have longer duration of action than endogenous and synthetic Phenylephrine, metaproterenol, albuterol Catecholamines: chemical structures of a substance that can produce a sympathomimetic response Noncatecholamines: stimulate adrenergic receptors Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.

Epinephrine (Adrenaline) Nonselective Action Alpha1 increases the blood pressure. Beta1 increases heart rate. Beta2 promotes bronchodilation. Contraindications and caution Cardiac dysrhythmias, hypertension Hyperthyroidism Pregnancy Epinephrine is nonselective, as it excites three different adrenergic receptors approximately equally. Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.

Epinephrine (Cont.) Action Uses Inotropic Vasoconstrictor Bronchodilator Uses Anaphylaxis, anaphylactic shock Bronchospasms Cardiogenic shock, cardiac arrest Inotropic: strengthens myocardial contraction, increasing cardiac output Vasoconstriction: increases heart rate and systolic blood pressure Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.

Epinephrine (Cont.) Side effects/adverse reactions Drug interaction 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.

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. Patient should be placed on cardiac monitor for early detection of dysrhythmias. Monitor urine output for early detection of decreased renal perfusion. Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.

Albuterol (Proventil) Selective Acts on beta2-adrenergic receptors Promotes bronchodilation Uses Treats bronchospasm, asthma, bronchitis, COPD Caution Severe cardiac disease Hypertension, hyperthyroidism Diabetes mellitus, pregnancy Albuterol is selective for beta2-adrenergic receptors so response is purely bronchodilation. Refer to Table 18-2, Adrenergic Drugs (Alpha1, Beta1, and Beta2). Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.

Albuterol (Cont.) Side effects/adverse reactions Drug interaction 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 Refer to Prototype Drug Chart 18-2, Albuterol. Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.

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.

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.

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.

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.

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.

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.

Alpha Blockers Drugs that inhibit a response at alpha-adrenergic 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.

Beta-Adrenergic Blockers Beta blocker action Decrease BP and pulse Nonselective beta blockers Blocks beta1 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.

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.

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.

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.

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.

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. Adrenergic neuron blockers are drugs that block release of norepinephrine from the sympathetic terminal neurons. Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.

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.

Practice Question #1 When teaching a patient who has been prescribed metoprolol (Lopressor) about side/adverse effects, which is the highest priority teaching point? 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. Answer: B Rationale: It is most important for the patient to learn how to monitor the heart rate because of the side effect of bradycardia with metoprolol. Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.

Practice Question #2 Stimulation of which adrenergic receptor results in dilation of vessels and decrease in blood pressure? Alpha1 Alpha2 Beta1 Beta2 Answer: B Rationale: When alpha2 receptors are stimulated, they inhibit the release of norepinephrine, leading to a decrease in vasoconstriction. This results in vasodilation and a decrease in blood pressure. Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.

Practice Question #3 The nurse is teaching the patient about the side effects of atenolol (Tenormin). These include pupillary constriction. blood vessel dilation. bronchospasm. tachycardia. Answer: C Rationale: The side effects commonly associated with beta blockers are bradycardia, hypotension, headache, dizziness, cold extremities, hypoglycemia, and bronchospasm. Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.

Practice Question #4 A nurse is administering epinephrine to a patient during a cardiac arrest. The primary desired action of this medication is to stimulate a heart rate. decrease cerebral blood flow. initiate respirations. increase blood flow to the kidneys. Answer: A Rationale: Epinephrine is a potent inotropic (strengthens myocardial contraction) drug that increases cardiac output, promotes vasoconstriction and systolic blood pressure elevation, increases heart rate, and produces bronchodilation. High doses can result in cardiac dysrhythmias necessitating electrocardiogram (ECG) monitoring. Epinephrine can also cause renal vasoconstriction, thereby decreasing renal perfusion and urinary output. Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.

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 Answer: B Rationale: The side effects commonly associated with atenolol (Tenormin), which is a beta blocker, include bradycardia, hypotension, headache, dizziness, cold extremities, hypoglycemia, and bronchospasm. Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.

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) Answer: C Rationale: The antidote for IV extravasation of dopamine is phentolamine mesylate (Regitine) 5 to 10 mg, diluted in 10 to 15 mL of saline infiltrated into the area. Norepinephrine bitartrate (Levophed) is an adrenergic agonist; nadolol (Corgard) is a beta1 and beta2 adrenergic blocker, and clonidine (Catapres) is a selective alpha2-adrenergic agonist (sympathomimetic) used primarily to treat hypertension. Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.