Adrenergic-Blocking Drugs

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CHAPTER 18CHAPTER 18

Adrenergic-Blocking DrugsAdrenergic-Blocking Drugs


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)

(alpha)-blockers and (alpha)-blockers and (beta)-blockers(beta)-blockers


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 -blockers, -blockers, -blockers, or -blockers, or --––blockersblockers



Sympatholytics inhibit—or LYSE—Sympatholytics inhibit—or LYSE—sympathetic stimulationsympathetic stimulation



Classified by the type of adrenergic receptor Classified by the type of adrenergic receptor they blockthey block11 and and 22 receptors receptors 11 and and 22 receptors receptors


Drug Effects and IndicationsDrug Effects and Indications

Ergot alkaloids (Ergot alkaloids (-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


Drug Effects and Indications Drug Effects and Indications (cont’d)(cont’d)

-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


Drug Effects and Indications Drug Effects and Indications (cont’d)(cont’d)

-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


-Blockers: Adverse Effects-Blockers: Adverse Effects

Body SystemBody System Adverse EffectsAdverse Effects

CardiovascularCardiovascular Palpitations, orthostaticPalpitations, orthostatichypotension, 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


-Blockers: Adverse Effects (cont’d)-Blockers: Adverse Effects (cont’d)


GastrointestinalGastrointestinal Nausea, vomiting, diarrhea,Nausea, vomiting, diarrhea,constipation, abdominal painconstipation, abdominal pain

OtherOther Incontinence, nosebleed,Incontinence, nosebleed,tinnitus, dry mouth, pharyngitis,tinnitus, dry mouth, pharyngitis,rhinitisrhinitis


Common Common -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)


-Blockers-Blockers

Block stimulation of Block stimulation of receptors in receptors in the SNSthe SNS

Compete with norepinephrine and Compete with norepinephrine and epinephrineepinephrine

Selective and nonselective Selective and nonselective -blockers-blockers Nonselective Nonselective -blockers block both -blockers block both 11 and and 22

receptorsreceptors


ReceptorsReceptors

1 1 receptorsreceptors Located primarily on the heartLocated primarily on the heart -blockers selective for these receptors -blockers selective for these receptors

are called cardioselective are called cardioselective -blockers-blockers


Receptors (cont’d)Receptors (cont’d)

2 2 receptorsreceptors Located primarily on smooth muscles Located primarily on smooth muscles

of bronchioles and blood vesselsof bronchioles and blood vessels


Mechanism of ActionMechanism of Action

Cardioselective (Cardioselective (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


Mechanism of Action (cont’d)Mechanism of Action (cont’d)

Nonselective (Nonselective (11 and and 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


IndicationsIndications

Antiangina:Antiangina: Decreases demand forDecreases demand formyocardial oxygenmyocardial oxygen

Cardioprotective:Cardioprotective: Inhibits stimulation fromInhibits stimulation fromcirculatingcirculating

catecholaminescatecholamines Class II antidysrhythmics Class II antidysrhythmics


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)


Adverse Effects: Adverse Effects: -Blockers-Blockers


BloodBlood Agranulocytosis, thrombocytopeniaAgranulocytosis, thrombocytopenia

CardiovascularCardiovascular AV block, bradycardia, AV block, bradycardia, heart failure, peripheral vascularheart failure, peripheral vascular

insufficiencyinsufficiency

CNSCNS Dizziness, mental depression,Dizziness, mental depression,lethargy, hallucinationslethargy, hallucinations


Adverse Effects: Adverse Effects: Adrenergic-Blocking DrugsAdrenergic-Blocking Drugs

-blockers-blockersBody SystemBody System Adverse EffectsAdverse Effects

GastrointestinalGastrointestinal Nausea, dry mouth, vomiting,Nausea, dry mouth, vomiting,diarrhea, cramps, ischemic diarrhea, cramps, ischemic colitiscolitis

OtherOther Impotence, rash, alopecia,Impotence, rash, alopecia,bronchospasmbronchospasm


-Blockers: Examples-Blockers: Examples

acebutolol (Sectral)acebutolol (Sectral) carvedilol (Coreg)carvedilol (Coreg) labetalol (Trandate)labetalol (Trandate) metoprolol (Lopressor)metoprolol (Lopressor)

atenolol (Tenormin)atenolol (Tenormin) esmolol (Brevibloc)esmolol (Brevibloc) sotalol (Betapace)sotalol (Betapace) propranolol (Inderal)propranolol (Inderal)


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


Adrenergic-Blocking Drugs: Adrenergic-Blocking Drugs: Nursing Implications (cont’d)Nursing Implications (cont’d)

Remember that Remember that -blockers may precipitate -blockers may precipitate hypotensionhypotension

Remember that some Remember that some -blockers may -blockers may precipitate bradycardia, hypotension, precipitate bradycardia, hypotension, heart block, heart failure, and heart block, heart failure, and bronchoconstrictionbronchoconstriction



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



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



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


-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


-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


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

Adrenergic-Blocking Drugs

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