Adrenergic-Blocking Drugs

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CHAPTER 18CHAPTER 18
Adrenergic-Blocking DrugsAdrenergic-Blocking Drugs

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Adrenergic BlockersAdrenergic Blockers

Bind to adrenergic receptors, but inhibit or Bind to adrenergic receptors, but inhibit or
block stimulation of the sympathetic nervous block stimulation of the sympathetic nervous
system (SNS) system (SNS)

a a (alpha)-blockers and (alpha)-blockers and bb(beta)-blockers(beta)-blockers

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Adrenergic Blockers (cont’d)Adrenergic Blockers (cont’d)

Have the opposite effect of adrenergic drugsHave the opposite effect of adrenergic drugs

Also known as:Also known as:
Adrenergic antagonists Adrenergic antagonists
SympatholyticsSympatholytics
aa-blockers, -blockers, bb-blockers, or -blockers, or aa--bb––blockersblockers

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Adrenergic Blockers (cont’d)Adrenergic Blockers (cont’d)
Sympatholytics inhibit—or LYSE—Sympatholytics inhibit—or LYSE—
sympathetic stimulationsympathetic stimulation

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Adrenergic Blockers (cont’d)Adrenergic Blockers (cont’d)
Classified by the type of adrenergic receptor Classified by the type of adrenergic receptor
they blockthey block
 a a
11 and and aa
22 receptors receptors
 bb
11 and and bb
22 receptors receptors

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Drug Effects and IndicationsDrug Effects and Indications
Ergot alkaloids (Ergot alkaloids (aa-blockers)-blockers)

Constrict dilated arterioles in the brainConstrict dilated arterioles in the brain

Used to treat vascular headaches (migraines)Used to treat vascular headaches (migraines)

Stimulate uterine contractions (oxytocics) and Stimulate uterine contractions (oxytocics) and
induce local vasoconstrictioninduce local vasoconstriction

Used to control postpartum bleedingUsed to control postpartum bleeding

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Drug Effects and Indications Drug Effects and Indications
(cont’d)(cont’d)
aa-blockers-blockers

Cause both arterial and venous dilation, reducing Cause both arterial and venous dilation, reducing
peripheral vascular resistance and BPperipheral vascular resistance and BP

Used to treat hypertensionUsed to treat hypertension

Effect on receptors on prostate gland and bladder Effect on receptors on prostate gland and bladder
decreased resistance to urinary outflow, thus reducing decreased resistance to urinary outflow, thus reducing
urinary obstruction and relieving effects of BPHurinary obstruction and relieving effects of BPH

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Drug Effects and Indications Drug Effects and Indications
(cont’d)(cont’d)
aa-blockers (cont'd)-blockers (cont'd)

Used to control and prevent hypertension in patients Used to control and prevent hypertension in patients
with pheochromocytomawith pheochromocytoma

Phentolamine Phentolamine
Quickly reverses the potent vasoconstrictive effects of Quickly reverses the potent vasoconstrictive effects of
extravasated vasopressors such as norepinephrine or extravasated vasopressors such as norepinephrine or
epinephrineepinephrine
Restores blood flow and prevents tissue necrosisRestores blood flow and prevents tissue necrosis

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aa-Blockers: Adverse Effects-Blockers: Adverse Effects
Body SystemBody System Adverse EffectsAdverse Effects
CardiovascularCardiovascular Palpitations, orthostaticPalpitations, orthostatic
hypotension, tachycardia, hypotension, tachycardia,
edema, dysrhythmias, chest painedema, dysrhythmias, chest pain
CNSCNS Dizziness, headache, drowsiness,Dizziness, headache, drowsiness,
anxiety, depression, vertigo,anxiety, depression, vertigo,
weakness, numbness, fatigueweakness, numbness, fatigue

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aa-Blockers: Adverse Effects (cont’d)-Blockers: Adverse Effects (cont’d)
Body SystemBody System Adverse EffectsAdverse Effects
GastrointestinalGastrointestinalNausea, vomiting, diarrhea,Nausea, vomiting, diarrhea,
constipation, abdominal painconstipation, abdominal pain
OtherOther Incontinence, nosebleed,Incontinence, nosebleed,
tinnitus, dry mouth, pharyngitis,tinnitus, dry mouth, pharyngitis,
rhinitisrhinitis

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Common Common aa-Blockers-Blockers

ergotamine tartrate (Ergostat)ergotamine tartrate (Ergostat)

phenoxybenzamine HCl (Dibenzyline)phenoxybenzamine HCl (Dibenzyline)

phentolamine (Regitine)phentolamine (Regitine)

prazosin (Minipress)prazosin (Minipress)

tolazoline (Priscoline)tolazoline (Priscoline)

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bb-Blockers-Blockers

Block stimulation of Block stimulation of bb receptors in receptors in
the SNSthe SNS

Compete with norepinephrine and Compete with norepinephrine and
epinephrineepinephrine

Selective and nonselective Selective and nonselective bb-blockers-blockers
Nonselective Nonselective bb-blockers block both -blockers block both bb
11 and and bb
22
receptorsreceptors

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bb ReceptorsReceptors
bb
1 1 receptorsreceptors

Located primarily on the heartLocated primarily on the heart

bb-blockers selective for these receptors -blockers selective for these receptors
are called cardioselective are called cardioselective bb-blockers-blockers

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bb Receptors (cont’d)Receptors (cont’d)
bb
2 2 receptorsreceptors

Located primarily on smooth muscles Located primarily on smooth muscles
of bronchioles and blood vesselsof bronchioles and blood vessels

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Mechanism of ActionMechanism of Action
Cardioselective (Cardioselective (bb
11))

Reduces SNS stimulation of the heartReduces SNS stimulation of the heart

Decreases heart rateDecreases heart rate

Prolongs SA node recoveryProlongs SA node recovery

Slows conduction rate through the AV nodeSlows conduction rate through the AV node

Decreases myocardial contractility, thus Decreases myocardial contractility, thus
reducing myocardial oxygen demandreducing myocardial oxygen demand

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Mechanism of Action (cont’d)Mechanism of Action (cont’d)
Nonselective (Nonselective (bb
11 and and bb
22))

Effects on heart:Effects on heart:Same as cardioselectiveSame as cardioselective

Bronchioles:Bronchioles: Constriction, resulting in Constriction, resulting in
narrowing of airways and narrowing of airways and
shortness of breathshortness of breath

Blood vessels:Blood vessels: VasoconstrictionVasoconstriction

Other effectsOther effects

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IndicationsIndications

Antiangina:Antiangina: Decreases demand forDecreases demand for
myocardial oxygenmyocardial oxygen

Cardioprotective:Cardioprotective: Inhibits stimulation fromInhibits stimulation from
circulatingcirculating
catecholaminescatecholamines

Class II antidysrhythmics Class II antidysrhythmics

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Indications (cont’d)Indications (cont’d)

AntihypertensiveAntihypertensive

Some are used to treat heart failureSome are used to treat heart failure

Treatment of migraine headachesTreatment of migraine headaches

Glaucoma (topical use)Glaucoma (topical use)

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Adverse Effects: Adverse Effects: bb-Blockers-Blockers
Body SystemBody System Adverse EffectsAdverse Effects
BloodBlood Agranulocytosis, thrombocytopeniaAgranulocytosis, thrombocytopenia
CardiovascularCardiovascularAV block, bradycardia, AV block, bradycardia,
heart failure, peripheral vascularheart failure, peripheral vascular
insufficiencyinsufficiency
CNSCNS Dizziness, mental depression,Dizziness, mental depression,
lethargy, hallucinationslethargy, hallucinations

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Adverse Effects: Adverse Effects:
Adrenergic-Blocking DrugsAdrenergic-Blocking Drugs
bb-blockers-blockers
Body SystemBody System Adverse EffectsAdverse Effects
GastrointestinalGastrointestinalNausea, dry mouth, vomiting,Nausea, dry mouth, vomiting,
diarrhea, cramps, ischemic diarrhea, cramps, ischemic
colitiscolitis
OtherOther Impotence, rash, alopecia,Impotence, rash, alopecia,
bronchospasmbronchospasm

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bb-Blockers: Examples-Blockers: Examples

acebutolol (Sectral)acebutolol (Sectral)

carvedilol (Coreg)carvedilol (Coreg)

labetalol (Trandate)labetalol (Trandate)

metoprolol (Lopressor)metoprolol (Lopressor)
 atenolol (Tenormin)
 esmolol (Brevibloc)
 sotalol (Betapace)
 propranolol (Inderal)

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Adrenergic-Blocking Drugs: Adrenergic-Blocking Drugs:
Nursing ImplicationsNursing Implications

Assess for allergies and history of COPD, Assess for allergies and history of COPD,
hypotension, cardiac dysrhythmias, hypotension, cardiac dysrhythmias,
bradycardia, heart failure, or other bradycardia, heart failure, or other
cardiovascular problemscardiovascular problems
Any preexisting condition that might be Any preexisting condition that might be
exacerbated by the use of these drugs might be a exacerbated by the use of these drugs might be a
contraindicationcontraindication to their use to their use

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Adrenergic-Blocking Drugs: Adrenergic-Blocking Drugs:
Nursing Implications (cont’d)Nursing Implications (cont’d)

Remember that Remember that aa-blockers may precipitate -blockers may precipitate
hypotensionhypotension

Remember that some Remember that some bb-blockers may -blockers may
precipitate bradycardia, hypotension, precipitate bradycardia, hypotension,
heart block, heart failure, and heart block, heart failure, and
bronchoconstrictionbronchoconstriction

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Adrenergic-Blocking Drugs: Adrenergic-Blocking Drugs:
Nursing Implications (cont’d)Nursing Implications (cont’d)

Avoid OTC medications because of possible Avoid OTC medications because of possible
interactionsinteractions

Possible drug interactions may occur with:Possible drug interactions may occur with:
Antacids (aluminum hydroxide type)Antacids (aluminum hydroxide type)
Antimuscarinics/anticholinergicsAntimuscarinics/anticholinergics
Diuretics and cardiovascular drugsDiuretics and cardiovascular drugs
Neuromuscular blocking drugsNeuromuscular blocking drugs
Oral hypoglycemic drugsOral hypoglycemic drugs

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Adrenergic-Blocking Drugs: Adrenergic-Blocking Drugs:
Nursing Implications (cont’d)Nursing Implications (cont’d)

Encourage patients to take medications Encourage patients to take medications
as prescribedas prescribed

These medications should never be These medications should never be
stopped abruptlystopped abruptly

Report constipation or the development of Report constipation or the development of
any urinary hesitancy or bladder distentionany urinary hesitancy or bladder distention

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Adrenergic-Blocking Drugs: Adrenergic-Blocking Drugs:
Nursing Implications (cont’d)Nursing Implications (cont’d)

Teach patients to change positions slowly to Teach patients to change positions slowly to
prevent or minimize postural hypotensionprevent or minimize postural hypotension

Avoid caffeine (excessive irritability)Avoid caffeine (excessive irritability)

Avoid alcohol ingestion and hazardous Avoid alcohol ingestion and hazardous
activities until blood levels become stableactivities until blood levels become stable

Patients should notify their physician if Patients should notify their physician if
palpitations, dyspnea, nausea, or vomiting palpitations, dyspnea, nausea, or vomiting
occursoccurs

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bb-Blocking Drugs: -Blocking Drugs:
Nursing ImplicationsNursing Implications

Rebound hypertension or chest pain may occur if Rebound hypertension or chest pain may occur if
this medication is discontinued abruptlythis medication is discontinued abruptly

Patients should notify their physician if they Patients should notify their physician if they
become ill and unable to take medicationbecome ill and unable to take medication

Inform patients that they may notice a decrease Inform patients that they may notice a decrease
in their tolerance for exercise; dizziness and in their tolerance for exercise; dizziness and
fainting may occur with increased activity. Notify fainting may occur with increased activity. Notify
the physician if these problems occurthe physician if these problems occur

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bb-Blocking Drugs: -Blocking Drugs:
Nursing Implications (cont’d)Nursing Implications (cont’d)
Patients should report the following to Patients should report the following to
their physician:their physician:

Weight gain of more than 2 pounds in 1 day or 5 lb Weight gain of more than 2 pounds in 1 day or 5 lb
within 1 weekwithin 1 week

Edema of the feet or anklesEdema of the feet or ankles

Shortness of breathShortness of breath

Excessive fatigue or weaknessExcessive fatigue or weakness

Syncope or dizzinessSyncope or dizziness

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Adrenergic-Blocking Drugs: Adrenergic-Blocking Drugs:
Nursing ImplicationsNursing Implications
Monitor for adverse effectsMonitor for adverse effects
Monitor for therapeutic effectsMonitor for therapeutic effects

Decreased chest pain in patients with anginaDecreased chest pain in patients with angina

Return to normal BP and PReturn to normal BP and P

Other specific effects, depending on the useOther specific effects, depending on the use