Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. CHAPTER 17 Adrenergic Drugs

Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Adrenergic Drugs: Definition Drugs that stimulate the sympathetic nervous system (SNS)

Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Adrenergic Drugs: Definition (cont’d) Also known as:  Adrenergic agonists  Sympathomimetics

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Characteristics Mimic the effects of the SNS neurotransmitters:  norepinephrine (NE)  epinephrine (EPI)  dopamine

Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Adrenergic Receptors  Located throughout the body  Are receptors for the sympathetic neurotransmitters   (alpha)-adrenergic receptors   (beta)-adrenergic receptors  Dopaminergic receptors: respond only to dopamine

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 -Adrenergic Receptors  Divided into  1 and  2 receptors  Differentiated by their location on nerves

Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc.  1 -Adrenergic Receptors Located on postsynaptic effector cells (the cell, muscle, or organ that the nerve stimulates)

Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc.  2 -Adrenergic Receptors  Located on presynaptic nerve terminals (the nerve that stimulates the effector cells)  Control the release of neurotransmitters

Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Predominant  -Adrenergic Agonist Responses  Vasoconstriction  CNS stimulation

Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc.  -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

Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc.  -Adrenergic Agonist Response  Results in:  Bronchial, GI, and uterine smooth muscle relaxation  Glycogenolysis  Cardiac stimulation

Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. 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

Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Responses to Stimulation LocationReceptor 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

Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Responses to Stimulation (cont’d) LocationReceptorResponse Gastrointestinal: Muscle  2 Decreased motility Sphincters  1 Constriction

Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Responses to Stimulation (cont’d) LocationReceptorResponse Genitourinary: Bladder  1 Constriction sphincter Penis  1 Ejaculation Uterus  1 Contraction  2 Relaxation

Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Responses to Stimulation (cont’d) LocationReceptorResponse Respiratory: Bronchial  2 Dilation muscles Liver  2 Glycogenolysis Pupils  1 Dilation

Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Catecholamines  Substances that can produce a sympathomimetic response  Endogenous  epinephrine, norepinephrine, dopamine  Synthetic  dobutamine, phenylephrine

Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Mechanism of Action  Direct-acting sympathomimetic  Binds directly to the receptor and causes a physiologic response

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Mechanism of Action (cont’d) 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

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Mechanism of Action (cont’d) Mixed-acting sympathomimetic  Directly stimulates the receptor by binding to it and  Indirectly stimulates the receptor by causing the release of stored neurotransmitters from the vesicles in the nerve endings

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Drug Effects 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)

Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Drug Effects (cont’d) 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)

Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Drug Effects (cont’d) 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

Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Indications Bronchodilators: treatment of asthma and bronchitis  Drugs that stimulate  2 -adrenergic receptors of bronchial smooth muscles, causing relaxation, resulting in bronchodilation

Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc.  2 -Adrenergic Drugs Examples:  albuterol  epinephrine  levalbuterol  metaproterenol  Others * Used to stop premature labor—causes relaxation of uterine smooth muscle  ephedrine  isoetharine  salmeterol  terbutaline*

Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Indications (cont’d)  Reduction of intraocular pressure and causes mydriasis (pupil dilation): treatment of open- angle glaucoma   or  2 receptors, or both – Examples: epinephrine and dipivefrin

Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Indications (cont’d)  Temporary relief of conjunctival congestion (eyes)   -adrenergic receptors  Examples: – epinephrine – naphazoline – epinephrine – naphazoline – phenylephrine – tetrahydrozoline – phenylephrine – tetrahydrozoline

Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Indications (cont’d) Nasal decongestant  Intranasal (topical) application causes constriction of dilated arterioles and reduction of nasal blood flow, thus decreasing congestion   1 -adrenergic stimulation

Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Topical Nasal Decongestants Examples:  naphazoline  tetrahydrozoline  epinephrine  ephedrine  phenylephrine

Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Vasoactive Sympathomimetics (Pressors, Inotropes)  Also called cardioselective sympathomimetics  Used to support the heart during cardiac failure or shock; various  and  receptors affected

Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Vasoactive Sympathomimetics (Pressors, Inotropes) (cont’d) Examples:  dobutamine  ephedrine  fenoldopam  methoxamine Others  dopamine  epinephrine  phenylephrine  norepinephrine

Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc.  -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)

Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc.  -Adrenergic Adverse Effects  CNS  Mild tremors, headache, nervousness, dizziness  Cardiovascular  Increased heart rate, palpitations (dysrhythmias), fluctuations in BP  Other  Sweating, nausea, vomiting, muscle cramps

Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Interactions  Anesthetic drugs  Tricyclic antidepressants  MAOIs  Antihistamines

Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Interactions (cont’d)  Thyroid preparations  Antihypertensives  Will directly antagonize another adrenergic drug, resulting in reduced effects

Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Nursing Implications  Assess for allergies and history of hypertension, cardiac dysrhythmias, or other cardiovascular disease  Assess renal, hepatic, and cardiac function before treatment

Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Nursing Implications (cont’d)  Perform baseline assessment of vital signs, peripheral pulses, skin color, temperature, and capillary refill; include postural blood pressure and pulse  Follow administration guidelines carefully

Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Nursing Implications (cont’d) 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

Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. 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

Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. 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

Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Nursing Implications (cont’d)  Administering two adrenergic drugs together may precipitate severe cardiovascular effects such as tachycardia or hypertension

Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. 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

Mosby items and derived items © 2007, 2005, 2002 by Mosby, Inc., an affiliate of Elsevier Inc. Nursing Implications (cont’d) Monitor for therapeutic effects (asthma):  Return to normal respiratory rate  Improved breath sounds, fewer crackles  Increased air exchange  Decreased cough  Less dyspnea  Improved blood gases  Increased activity tolerance