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Chapter 19
Adrenergic-Blocking Drugs
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
Adrenergic Blockers
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Bind to adrenergic receptors, but inhibit or
block stimulation of the sympathetic nervous
system (SNS)
Have the opposite effect of adrenergic drugs
Inhibit—or lyse—sympathetic stimulation
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Adrenergic Blockers (cont’d)

Also known as:
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Adrenergic antagonists
Sympatholytics
Alpha blockers, beta blockers, or alpha-beta
blockers
Classified by the type of adrenergic receptor
they block


Alpha1 and alpha2 receptors
Beta1 and beta2 receptors
Copyright © 2014 by Mosby, an imprint of Elsevier Inc.
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Drug Effects and Indications:
Alpha Blockers
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Cause both arterial and venous dilation,
reducing peripheral vascular resistance and
BP
Used to treat hypertension
Effect on receptors on prostate gland and
bladder decreases resistance to urinary
outflow, thus reducing urinary obstruction and
relieving effects of benign prostatic
hyperplasia (BPH)
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Drug Effects and Indications:
Alpha Blockers (cont’d)
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Used to control and prevent hypertension in
patients with pheochromocytoma
Phentolamine
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Quickly reverses the potent vasoconstrictive
effects of extravasated vasopressors such as
norepinephrine or epinephrine
Restores blood flow and prevents tissue necrosis
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Classroom Response Question
When phentolamine is used to diagnose the
presence of pheochromocytoma, the nurse will
assess for what indicative finding?
A. Rapid decrease in blood pressure
B. Steady increase in blood pressure
C. Slower heart rate
D. Reduced cardiac ectopy
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Alpha Blockers: Adverse Effects
Body System
Cardiovascular
Adverse Effects
Palpitations, orthostatic
hypotension, tachycardia,
edema, chest pain
CNS
Dizziness, headache,
anxiety, depression,
weakness, numbness,
fatigue
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Alpha Blockers: Adverse Effects
(cont’d)
Body System
Gastrointestinal
Adverse Effects
Nausea, vomiting, diarrhea,
constipation, abdominal
pain
Other
Incontinence, dry mouth,
pharyngitis
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Classroom Response Question
When administering an alpha blocker for the first
time, it is most important for the nurse to assess
the patient for the development of
A.
B.
C.
D.
renal failure.
hypotension.
blood dyscrasia.
dysrhythmias.
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Common Alpha Blockers
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phenoxybenzamine HCl (Dibenzyline)
phentolamine (Regitine)
prazosin (Minipress)
terazosin (Hytrin)
alfuzosin (UroXatral)
tamsulosin (Flomax)
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Beta Blockers


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Block stimulation of beta receptors in
the SNS
Compete with norepinephrine and epinephrine
Can be selective or nonselective
Nonselective beta blockers block both beta1
and beta2 receptors
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Beta Receptors
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Beta1 receptors
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Located primarily on the heart
Beta blockers selective for these receptors
are called cardioselective beta blockers
Beta2 receptors

Located primarily on smooth muscle of bronchioles
and blood vessels
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Mechanism of Action

Cardioselective beta blockers (beta1)
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Reduce SNS stimulation of the heart
 Decrease heart rate
 Prolong sinoatrial (SA) node recovery
 Slow conduction rate through the AV node
 Decrease myocardial contractility, thus reducing
myocardial oxygen demand
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Mechanism of Action (cont’d)

Nonselective beta blockers (beta1 and beta2)
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Cause same effects on heart as cardioselective
beta blockers
Constrict bronchioles, resulting in narrowing of
airways and shortness of breath
Produce vasoconstriction of blood vessels
Other effects
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Indications
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Angina
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Cardioprotective
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Inhibits stimulation from circulating catecholamines
Dysrhythmias
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Decreases demand for myocardial oxygen
Class II antidysrhythmic
Migraine headache

Lipophilicity allows entry into CNS
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Classroom Response Question
A 58-year-old patient is recovering in the intensive care unit
after a myocardial infarction (MI). The nurse notes an order
for the beta blocker metoprolol (Lopressor). The purpose of
this drug is to
A. dilate the coronary arteries.
B. inhibit stimulation of the myocardium by circulating
catecholamines.
C. provide a positive inotropic effect.
D. maintain the patient’s blood pressure.
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Indications (cont’d)
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
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Antihypertensive
Heart failure
Glaucoma (topical use)
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Adverse Effects: Beta Blockers
Body System
Blood
Adverse Effects
Agranulocytosis,
thrombocytopenia
Cardiovascular
AV block, bradycardia, heart
failure
CNS
Dizziness, depression,
unusual dreams,
drowsiness
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Adverse Effects: Beta Blockers
Body System
Gastrointestinal
Adverse Effects
Nausea, vomiting,
constipation, diarrhea
Other
Impotence, alopecia,
wheezing, bronchospasm,
dry mouth
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Adverse Effects: Beta Blockers
(cont’d)
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Nonselective beta blockers may interfere with
normal responses to hypoglycemia (tremor,
tachycardia, nervousness)
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
May mask signs and symptoms of hypoglycemia
Use with caution in patients with diabetes mellitus
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Classroom Response Question
The nurse knows that the adverse effects of a
nonselective beta blocker are likely to be the most
immediately life threatening in which patient?
A. Patient with type I diabetes
B. Patient with asthma
C. Patient with gastroesophageal reflux disease
D. Patient with hypertension
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Beta Blockers: Examples
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atenolol (Tenormin)
carvedilol (Coreg)
esmolol (Brevibloc)
labetalol
(Normodyne)
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metoprolol
(Lopressor)
propranolol (Inderal)
sotalol (Betapace)
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Adrenergic-Blocking Drugs:
Nursing Implications

Assess for allergies and history of COPD,
hypotension, cardiac dysrhythmias,
bradycardia, heart failure, or other
cardiovascular problems

Any preexisting condition that might be
exacerbated by the use of these drugs might be a
contraindication to their use
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Adrenergic-Blocking Drugs:
Nursing Implications (cont’d)
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Remember that alpha blockers may
precipitate hypotension
Remember that some beta blockers may
precipitate bradycardia, hypotension,
heart block, heart failure, and
bronchoconstriction
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Adrenergic-Blocking Drugs:
Nursing Implications (cont’d)
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Avoid over-the-counter medications because
of possible interactions
Possible drug interactions may occur with:

Antacids (aluminum hydroxide type)
 Antimuscarinics/anticholinergics
 Diuretics and cardiovascular drugs
 Neuromuscular blocking drugs
 Oral hypoglycemic drugs
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Adrenergic-Blocking Drugs:
Nursing Implications (cont’d)
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Encourage patients to take medications
as prescribed
Instruct patients that these medications
should never be stopped abruptly
Inform patients to report constipation or the
development of urinary hesitancy or bladder
distention
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Adrenergic-Blocking Drugs:
Nursing Implications (cont’d)
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Teach patients to change positions slowly to
prevent or minimize postural hypotension
Instruct patients to avoid caffeine (excessive
irritability)
Instruct patients to avoid alcohol ingestion and
hazardous activities until blood levels become
stable
Instruct patients to notify their physician if
palpitations, dyspnea, nausea, or vomiting
occurs
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Adrenergic-Blocking Drugs:
Nursing Implications (cont’d)
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Monitor for adverse effects
Monitor for therapeutic effects
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Decreased chest pain in patients with angina
Return to normal BP and HR
Other specific effects, depending on the use
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Classroom Response Question
A patient with type 2 diabetes is taking a beta
blocker as part of treatment for hypertension.
Which complication is most likely to develop?
A. Hypertension
B. Hyperkalemia
C. Hypoglycemia
D. Angina
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Beta-Blocking Drugs:
Nursing Implications
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Rebound hypertension or chest pain may occur
if this medication is discontinued abruptly
Instruct patients to notify their physician if they
become ill and unable to take medication
Inform patients that they may notice a decrease
in tolerance for exercise (dizziness and fainting
may occur with increased activity), and have
patients notify the physician if these problems
occur
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Beta-Blocking Drugs:
Nursing Implications (cont’d)

Inform patients to report the following to their
physician:

Weight gain of more than 2 pounds in 1 day or 5
pounds in 1 week
 Edema of the feet or ankles
 Shortness of breath
 Excessive fatigue or weakness
 Syncope or dizziness
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