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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
Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.
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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.
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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.
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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.
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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 © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.
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Classification of Adrenergic
Agonists/Sympathomimetics

Direct-acting


Indirect-acting


Epinephrine, norepinephrine
Amphetamine
Mixed-acting

Ephedrine
Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.
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Catecholamines

Catecholamines



Endogenous
• Epinephrine, norepinephrine, dopamine
Synthetic
• Isoproterenol, dobutamine
Noncatecholamines

Most have longer duration of action than
endogenous and synthetic
• Phenylephrine, metaproterenol, albuterol
Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.
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Epinephrine (Adrenaline)


Nonselective
Action




Alpha1 increases the blood pressure.
Beta1 increases heart rate.
Beta2 promotes bronchodilation.
Contraindications and caution



Cardiac dysrhythmias, hypertension
Hyperthyroidism
Pregnancy
Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.
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Epinephrine (Cont.)

Action




Inotropic
Vasoconstrictor
Bronchodilator
Uses



Anaphylaxis, anaphylactic shock
Bronchospasms
Cardiogenic shock, cardiac arrest
Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.
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Epinephrine (Cont.)

Side effects/adverse reactions




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.
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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.
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Albuterol (Proventil)

Selective



Uses


Acts on beta2-adrenergic receptors
Promotes bronchodilation
Treats bronchospasm, asthma, bronchitis, COPD
Caution



Severe cardiac disease
Hypertension, hyperthyroidism
Diabetes mellitus, pregnancy
Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.
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Albuterol (Cont.)

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 © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.
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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.
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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.
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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.
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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.
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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.
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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.
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Alpha Blockers

Drugs that inhibit a response at alphaadrenergic 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.
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Beta-Adrenergic Blockers

Beta blocker action


Decrease BP and pulse
Nonselective beta blockers



Blocks beta1
• Decrease BP and pulse
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.
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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.
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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.
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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.
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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.
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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.
Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.
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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.
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Practice Question #1
When teaching a patient who has been
prescribed metoprolol (Lopressor) about
side/adverse effects, which is the highest
priority teaching point?
A.
B.
C.
D.
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.
Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.
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Practice Question #2
Stimulation of which adrenergic receptor results
in dilation of vessels and decrease in blood
pressure?
A.
B.
C.
D.
Alpha1
Alpha2
Beta1
Beta2
Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.
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Practice Question #3
The nurse is teaching the patient about the side
effects of atenolol (Tenormin). These include
A.
B.
C.
D.
pupillary constriction.
blood vessel dilation.
bronchospasm.
tachycardia.
Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.
31
Practice Question #4
A nurse is administering epinephrine to a
patient during a cardiac arrest. The primary
desired action of this medication is to
A.
B.
C.
D.
stimulate a heart rate.
decrease cerebral blood flow.
initiate respirations.
increase blood flow to the kidneys.
Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.
32
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
Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.
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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)
Copyright © 2015, 2012, 2009, 2006, 2003, 2000, 1997, 1993 by Saunders, an imprint of Elsevier Inc.
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