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.

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 DrugsAdrenergic 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 DrugsDopaminergic 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 DrugsResponses to Stimulation

Location Receptor Response

Cardiovascular:Blood vessels 1 Constriction

2 DilationCardiac muscle 1 Increased contractility

AV Node 1 Increased heart rate

SA Node 1 Increased heart rate

Gastrointestinal: Muscle: 2 Decreased motilitySphincters: 1 Constriction

ANS - Adrenergic DrugsResponses to Stimulation

(cont’d)Location Receptor Response

Genitourinary:Bladder sphincter 1 Constriction

Penis 1 Ejaculation

Uterus 1 Contraction2 Relaxation

Respiratory:Bronchial muscles 2 Dilation

Liver 2 Glycogenolysis

Pupils 1 Dilation

ANS - Adrenergic DrugsCatecholamines

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 DrugsResponse to Direct-Acting

Sympathomimetics

ANS - Adrenergic DrugsIndirect-acting

sympathomimetic

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 DrugsIndirect-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

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 DrugsVasoactive 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