Autonomic Nervous System Adrenergic Drugs

ANS - Adrenergic Drugs Describe the adrenergic drug effects on major body systems. Discuss the nursing process related to the care of patients receiving adrenergic drugs for cardiovascular, respiratory, gastrointestinal, and genitourinary systems.

Mimic the effects of the SNS neurotransmitters: ANS - Adrenergic Drugs Drugs that stimulate the sympathetic nervous system (SNS) Adrenergic agonists Sympathomimetics Mimic the effects of the SNS neurotransmitters: norepinephrine (NE) epinephrine (EPI) dopamine

ANS - Adrenergic Drugs

ANS - Adrenergic Drugs Adrenergic Receptors Located throughout the body Are receptors for the sympathetic neurotransmitters  (alpha)-adrenergic receptors  (beta)-adrenergic receptors Dopaminergic receptors: respond only to dopamine

ANS - Adrenergic Drugs -Adrenergic Receptors Divided into 1 and 2 receptors Differentiated by their location on nerves 1-Adrenergic Receptors Located on postsynaptic effector cells (the cell, muscle, or organ that the nerve stimulates) 2-Adrenergic Receptors Located on presynaptic nerve terminals (the nerve that stimulates the effector cells) Control the release of neurotransmitters Predominant -Adrenergic Agonist Responses Vasoconstriction CNS stimulation

ANS - Adrenergic Drugs -Adrenergic Receptors All are located on postsynaptic effector cells 1-adrenergic receptors—located primarily in the heart 2-adrenergic receptors—located in smooth muscle of the bronchioles, arterioles, and visceral organs -Adrenergic Agonist Response Results in: Bronchial, GI, and uterine smooth muscle relaxation Glycogenolysis Cardiac stimulation

ANS - Adrenergic Drugs Dopaminergic Receptors An additional adrenergic receptor Stimulated by dopamine Causes dilation of the following blood vessels, resulting in increased blood flow Renal Mesenteric Coronary Cerebral

ANS - Adrenergic Drugs Responses to Stimulation Location Receptor Response Cardiovascular: Blood vessels 1 Constriction 2 Dilation Cardiac muscle 1 Increased contractility AV Node 1 Increased heart rate SA Node 1 Increased heart rate Gastrointestinal: Muscle: 2 Decreased motility Sphincters: 1 Constriction

ANS - Adrenergic Drugs Responses to Stimulation (cont’d) Location Receptor Response Genitourinary: Bladder sphincter 1 Constriction Penis 1 Ejaculation Uterus 1 Contraction 2 Relaxation Respiratory: Bronchial muscles 2 Dilation Liver 2 Glycogenolysis Pupils 1 Dilation

ANS - Adrenergic Drugs Catecholamines Substances that can produce a sympathomimetic response Endogenous epinephrine, norepinephrine, dopamine Synthetic dobutamine, phenylephrine Mechanism of Action: Direct-acting sympathomimetic Binds directly to the receptor and causes a physiologic response

ANS - Adrenergic Drugs Response to Direct-Acting Sympathomimetics

ANS - Adrenergic Drugs Indirect-acting sympathomimetic Causes the release of catecholamine from the storage sites (vesicles) in the nerve endings The catecholamine then binds to the receptors and causes a physiologic response

ANS - Adrenergic Drugs Indirect-acting sympathomimetic

ANS - Adrenergic Drugs – Stimulation of -adrenergic receptors Stimulation of -adrenergic receptors on smooth muscles results in: Vasoconstriction of blood vessels Relaxation of GI smooth muscles Contraction of the uterus and bladder Male ejaculation Decreased insulin release Contraction of the ciliary muscles of the eye (dilated pupils)

ANS - Adrenergic Drugs Stimulation of 1-adrenergic receptors Stimulation of 1-adrenergic receptors on the myocardium, AV node, and SA node results in cardiac stimulation Increased force of contraction (positive inotropic effect) Increased heart rate (positive chronotropic effect) Increased conduction through the AV node (positive dromotropic effect)

ANS - Adrenergic Drugs Stimulation of 2-adrenergic receptors Stimulation of 2-adrenergic receptors on the airways results in: Bronchodilation (relaxation of the bronchi) Other effects of 2-adrenergic stimulation: Uterine relaxation Glycogenolysis in the liver Increased renin secretion in the kidneys

ANS - Adrenergic Drugs 2-Adrenergic Drugs Examples: Tx of acute bronchospasm (Asthma, COPD) albuterol (Proventil, Ventolin) epinephrine (Adrenalin) levalbuterol (Xopenex) metaproterenol (Alupent, Metaprel) ephedrine salmeterol (Serevent) terbutaline* (Brethine, Brethaire) * Used to stop premature labor—causes relaxation of uterine smooth muscle

ANS - Adrenergic Drugs Reduction of intraocular pressure Reduction of intraocular pressure and causes mydriasis (pupil dilation): treatment of open-angle glaucoma  or 2 receptors, or both – Examples: epinephrine and dipivefrin Temporary relief of conjunctival congestion (eyes) -adrenergic receptors Examples: – epinephrine (Primatene, Bronkaid) – phenylephrine (Neo-Synephrine) – tetrahydrozoline (Tyzine)

ANS - Adrenergic Drugs Nasal decongestant Intranasal (topical) application causes constriction of dilated arterioles and reduction of nasal blood flow, thus decreasing congestion 1-adrenergic stimulation Topical Nasal Decongestants tetrahydrozoline (Tyzine) epinephrine (Adrenalin) ephedrine phenylephrine (Neo-Synephrine)

ANS - Adrenergic Drugs Vasoactive Sympathomimetics ( Pressors, (Inotropes, cardioselective sympathomimetics) Used to support the heart during cardiac failure or shock; various  and  receptors affected Pressors: dobutamine (Dobutrex) ephedrine fenoldopam (Corlopam) methoxamine Dopamine (Intropin) Epinephrine (Adrenalin) Norepinephrine (Levophed) Phenylephrine (Neo-Synephrine)

ANS - Adrenergic Drugs -Adrenergic Adverse Effects CNS Headache, restlessness, excitement, insomnia, euphoria Cardiovascular Palpitations (dysrhythmias), tachycardia, vasoconstriction, hypertension Other Loss of appetite, dry mouth, nausea, vomiting, taste changes (rare)

ANS - Adrenergic Drugs -Adrenergic Adverse Effects CNS Mild tremors, headache, nervousness, dizziness Cardiovascular Increased heart rate, palpitations (dysrhythmias), fluctuations in BP Other Sweating, nausea, vomiting, muscle cramps

ANS - Adrenergic Drugs Interactions Anesthetic drugs Tricyclic antidepressants MAOIs Antihistamines Thyroid preparations Antihypertensives

ANS - Adrenergic Drugs Nursing Implications Assess for allergies and history of hypertension, cardiac dysrhythmias, or other cardiovascular disease Assess renal, hepatic, and cardiac function before treatment Perform baseline assessment of vital signs, peripheral pulses, skin color, temperature; include postural blood pressure and pulse Follow administration guidelines carefully Intravenous administration Check IV site often for infiltration Use clear IV solutions / Use an infusion pump Infuse drug slowly to avoid dangerous cardiovascular effects Monitor cardiac rhythm

ANS - Adrenergic Drugs Nursing Implications (cont’d) With chronic lung disease: Instruct patients to avoid factors that exacerbate their condition Encourage fluid intake (up to 3000 mL per day) if permitted Educate about proper dosing, use of equipment (MDI, spacer, nebulizer), and equipment care

ANS - Adrenergic Drugs Nursing Implications (cont’d) Salmeterol is indicated for prevention of bronchospasms, not management of acute symptoms Overuse of nasal decongestants may cause rebound nasal congestion or ulcerations Avoid OTC or other medications because of possible interactions Administering two adrenergic drugs together may precipitate severe cardiovascular effects such as tachycardia or hypertension

ANS - Adrenergic Drugs Nursing Implications (cont’d) Monitor for therapeutic effects: (cardiovascular uses) Decreased edema Increased urinary output Return to normal vital signs Improved skin color and temperature Increased LOC

ANS - Adrenergic Drugs Nursing Implications (cont’d) Monitor for therapeutic effects (bronchospasm/asthma): Return to normal respiratory rate Improved breath sounds, fewer rales Increased air exchange Decreased cough Less dyspnea Improved blood gases Increased activity tolerance