adrenergic blockers

Drugs Affecting TheDrugs Affecting TheAutonomic Nervous SystemAutonomic Nervous System

Adrenergic Agents and Adrenergic Agents and Adrenergic-Blocking AgentsAdrenergic-Blocking Agents

Adrenergic AgentsAdrenergic Agents

• Drugs that stimulate the sympathetic nervous Drugs that stimulate the sympathetic nervous system (SNS)system (SNS)

Also known asAlso known as

• adrenergic agonists or sympathomimeticsadrenergic agonists or sympathomimetics

Mimic the effects of the SNS neurotransmitters:Mimic the effects of the SNS neurotransmitters:

• norepinephrine (NE) and epinephrine (EPI)norepinephrine (NE) and epinephrine (EPI)

Adrenergic ReceptorsAdrenergic Receptors

• Located throughout the bodyLocated throughout the body

• Are receptors for the sympathetic Are receptors for the sympathetic neurotransmittersneurotransmitters

Alpha-adrenergic receptors: respond to NEAlpha-adrenergic receptors: respond to NE

Beta-adrenergic receptors: respond to EPIBeta-adrenergic receptors: respond to EPI

Alpha-Adrenergic ReceptorsAlpha-Adrenergic Receptors

• Divided into alpha1 and alphaDivided into alpha1 and alpha22 receptors receptors

• Differentiated by their location on nervesDifferentiated by their location on nerves

AlphaAlpha11-Adrenergic Receptors-Adrenergic Receptors

• Located on postsynaptic effector cells Located on postsynaptic effector cells (the cell, muscle, or organ that the nerve (the cell, muscle, or organ that the nerve stimulates)stimulates)

AlphaAlpha22-Adrenergic Receptors-Adrenergic Receptors

• Located on presynaptic nerve terminals Located on presynaptic nerve terminals (the nerve that stimulates the effector cells)(the nerve that stimulates the effector cells)

• Control the release of neurotransmittersControl the release of neurotransmitters

The predominant alpha-adrenergic The predominant alpha-adrenergic agonist responses are:agonist responses are:

• Vasoconstriction and CNS stimulationVasoconstriction and CNS stimulation

Beta-Adrenergic ReceptorsBeta-Adrenergic Receptors

All are located on postsynaptic effector cellsAll are located on postsynaptic effector cells

• BetaBeta11-adrenergic receptors—located primarily -adrenergic receptors—located primarily in the heartin the heart

• BetaBeta22-adrenergic receptors—located in smooth -adrenergic receptors—located in smooth muscle of the bronchioles, arterioles, and visceral muscle of the bronchioles, arterioles, and visceral organsorgans

The beta-adrenergic agonist The beta-adrenergic agonist response results in:response results in:

• Bronchial, GI, and uterine smooth muscle Bronchial, GI, and uterine smooth muscle relaxationrelaxation

• GlycogenolysisGlycogenolysis

• Cardiac stimulationCardiac stimulation

Dopaminergic ReceptorsDopaminergic Receptors

• An additional adrenergic receptorAn additional adrenergic receptor

• Stimulated by dopamineStimulated by dopamine

• Causes dilation of the following blood Causes dilation of the following blood vessels, resulting in INCREASED blood flowvessels, resulting in INCREASED blood flow

– RenalRenal

– MesentericMesenteric

– CoronaryCoronary

– CerebralCerebral

Adrenergic Receptor ResponsesAdrenergic Receptor Responsesto Stimulationto Stimulation

LOCATIONLOCATION RECEPTORRECEPTOR RESPONSERESPONSECardiovascularCardiovascular

Blood vesselsBlood vessels alphaalpha11 and beta and beta22 Constriction /Constriction /dilationdilation

Cardiac muscleCardiac muscle betabeta11 IncreasedIncreasedcontractilitycontractility

AV NodeAV Node betabeta11 Increased Increased heart rateheart rate

SA NodeSA Node betabeta11 Increased Increased heart rateheart rate

LOCATIONLOCATION RECEPTORRECEPTOR RESPONSERESPONSEGastrointestinalGastrointestinal

MuscleMuscle betabeta22 Decreased Decreased motilitymotility

SphinctersSphincters alphaalpha11 ConstrictionConstriction

LOCATIONLOCATION RECEPTORRECEPTOR RESPONSERESPONSEGenitourinaryGenitourinary

BladderBladder alphaalpha11 ConstrictionConstrictionsphinctersphincter

PenisPenis alphaalpha11 EjaculationEjaculation

UterusUterus alphaalpha11 and beta and beta22 Contraction/Contraction/relaxationrelaxation

LOCATIONLOCATION RECEPTORRECEPTOR RESPONSERESPONSERespiratoryRespiratory

BronchialBronchial betabeta22 Dilation/relaxationDilation/relaxationmusclesmuscles

Catecholamines Catecholamines

Substances that can produce a sympathomimetic Substances that can produce a sympathomimetic responseresponse

Endogenous:Endogenous:

• epinephrine, norepinephrine,dopamineepinephrine, norepinephrine,dopamine

Synthetic:Synthetic:

• isoproterenol, dobutamine, phenylephrineisoproterenol, dobutamine, phenylephrine

Adrenergic Agents Adrenergic Agents Mechanism of ActionMechanism of Action

Direct-acting sympathomimetic:Direct-acting sympathomimetic:

• Binds directly to the receptor and causes a Binds directly to the receptor and causes a physiologic responsephysiologic response

Indirect-acting sympathomimetic:Indirect-acting sympathomimetic:

• Causes the release of catecholamine from the Causes the release of catecholamine from the storage sites (vesicles) in the nerve endingsstorage sites (vesicles) in the nerve endings

• The catecholamine then binds to the receptors and The catecholamine then binds to the receptors and causes a physiologic responsecauses a physiologic response

Mixed-acting sympathomimetic:Mixed-acting sympathomimetic:

• Directly stimulates the receptor by binding Directly stimulates the receptor by binding to itto it

ANDAND

• Indirectly stimulates the receptor by causing Indirectly stimulates the receptor by causing the release of stored neurotransmitters from the release of stored neurotransmitters from the vesicles in the nerve endingsthe vesicles in the nerve endings

Drug Effects of Adrenergic AgentsDrug Effects of Adrenergic Agents

Stimulation of alpha-adrenergic receptors on Stimulation of alpha-adrenergic receptors on smooth muscles results in:smooth muscles results in:

• Vasoconstriction of blood vesselsVasoconstriction of blood vessels

• Relaxation of GI smooth musclesRelaxation of GI smooth muscles

• Contraction of the uterus and bladderContraction of the uterus and bladder

• Male ejaculationMale ejaculation

• Decreased insulin releaseDecreased insulin release

• Contraction of the ciliary muscles of the eye Contraction of the ciliary muscles of the eye (dilated pupils)(dilated pupils)

Stimulation of betaStimulation of beta22-adrenergic receptors on -adrenergic receptors on the airways results in:the airways results in:

• Bronchodilation (relaxation of the bronchi)Bronchodilation (relaxation of the bronchi)

• Uterine relaxationUterine relaxation

• Glycogenolysis in the liverGlycogenolysis in the liver

Stimulation of beta1-adrenergic receptors on Stimulation of beta1-adrenergic receptors on the myocardium, AV node, and SA node the myocardium, AV node, and SA node results in CARDIAC STIMULATION:results in CARDIAC STIMULATION:

• Increased force of contraction Increased force of contraction (positive (positive inotropicinotropic effect) effect)

• Increased heart rate Increased heart rate (positive (positive chronotropicchronotropic effect) effect)

• Increased conduction through the AV node Increased conduction through the AV node (positive (positive dromotropicdromotropic effect) effect)

Adrenergic Agents: Adrenergic Agents: Therapeutic UsesTherapeutic Uses

• Anorexiants: adjuncts to diet in the Anorexiants: adjuncts to diet in the short-term management of obesityshort-term management of obesity

Examples: Examples: benzphetaminebenzphetaminephenterminephenterminedextroamphetaminedextroamphetamineDexedrineDexedrine

Bronchodilators: treatment of asthma and Bronchodilators: treatment of asthma and bronchitisbronchitis

• Agents that stimulate betaAgents that stimulate beta22-adrenergic receptors -adrenergic receptors of bronchial smooth muscles causing relaxationof bronchial smooth muscles causing relaxation

Examples:Examples:

albuterolalbuterol ephedrineephedrine epinephrineepinephrineisoetharine isoetharine isoproterenolisoproterenol levalbuterollevalbuterolmetaproterenolmetaproterenol salmeterolsalmeterol terbutalineterbutaline

• These agents may also affect uterine and vascular These agents may also affect uterine and vascular smooth muscles.smooth muscles.

• Reduction of intraocular pressure and Reduction of intraocular pressure and mydriasis (pupil dilation): treatment of mydriasis (pupil dilation): treatment of open-angle glaucomaopen-angle glaucoma

Examples: Examples: epinephrine and dipivefrinepinephrine and dipivefrin

Nasal decongestant: Nasal decongestant:

• Intranasal (topical) application causes constriction Intranasal (topical) application causes constriction of dilated arterioles and reduction of nasal blood of dilated arterioles and reduction of nasal blood flow, thus decreasing congestion.flow, thus decreasing congestion.

Examples:Examples:epinephrineepinephrine ephedrineephedrine naphazoline naphazoline

phenylephrinephenylephrinetetrahydrozolinetetrahydrozoline

Ophthalmic Ophthalmic

• Topical application to the eye surface affects Topical application to the eye surface affects the vasculature of the eye, stimulating alpha the vasculature of the eye, stimulating alpha receptors on small arterioles, thus relieving receptors on small arterioles, thus relieving conjunctival congestion.conjunctival congestion.

Examples:Examples: epinephrineepinephrine naphazoline naphazoline phenylephrinephenylephrine

tetrahydrozolinetetrahydrozoline

Vasoactive sympathomimetics (pressors, Vasoactive sympathomimetics (pressors, inotropes), also called cardioselective inotropes), also called cardioselective sympathomimeticssympathomimetics

• Used to support the heart during cardiac failure Used to support the heart during cardiac failure or shock.or shock.

Examples:Examples:

dobutaminedobutamine dopaminedopamine ephedrine ephedrine epinephrineepinephrine fenoldopamfenoldopam isoproterenolisoproterenol

methoxaminemethoxamine norepinephrinenorepinephrinephenylephrinephenylephrine

Adrenergic Agents: Side EffectsAdrenergic Agents: Side Effects

Alpha-Adrenergic EffectsAlpha-Adrenergic Effects• CNS:CNS:

– headache, restlessness, excitement, insomnia, headache, restlessness, excitement, insomnia, euphoriaeuphoria

• Cardiovascular:Cardiovascular:– palpitations (dysrhythmias), tachycardia, palpitations (dysrhythmias), tachycardia,

vasoconstriction, hypertensionvasoconstriction, hypertension

• Other:Other:– anorexia, dry mouth, nausea, vomiting, taste anorexia, dry mouth, nausea, vomiting, taste

changes (rare)changes (rare)

Adrenergic Agents: Side EffectsAdrenergic Agents: Side Effects

Beta-Adrenergic EffectsBeta-Adrenergic Effects

• CNS:CNS:

– mild tremors, headache, nervousness, dizzinessmild tremors, headache, nervousness, dizziness

• Cardiovascular:Cardiovascular:

– increased heart rate, palpitations (dysrhythmias), increased heart rate, palpitations (dysrhythmias), fluctuations in BPfluctuations in BP

• Other:Other:

– sweating, nausea, vomiting, muscle crampssweating, nausea, vomiting, muscle cramps

Adrenergic Agents: InteractionsAdrenergic Agents: Interactions

• Anesthetic agentsAnesthetic agents

• Tricyclic antidepressantsTricyclic antidepressants

• MAOIsMAOIs

• AntihistaminesAntihistamines

• Thyroid preparationsThyroid preparations

• AntihypertensivesAntihypertensives

• Will directly antagonize another adrenergic Will directly antagonize another adrenergic agent, resulting in reduced effectsagent, resulting in reduced effects

Adrenergic Agents: Adrenergic Agents: Nursing ImplicationsNursing Implications• Assess for allergies and history of Assess for allergies and history of

hypertension, cardiac dysrhythmias, or other hypertension, cardiac dysrhythmias, or other cardiovascular disease.cardiovascular disease.

• Assess renal, hepatic, and cardiac function Assess renal, hepatic, and cardiac function before treatment.before treatment.

• Perform baseline assessment of vital signs, Perform baseline assessment of vital signs, peripheral pulses, skin color, temperature, peripheral pulses, skin color, temperature, and capillary refill. Include postural blood and capillary refill. Include postural blood pressure and pulse.pressure and pulse.

• Follow administration guidelines carefully.Follow administration guidelines carefully.

Adrenergic Agents: Adrenergic Agents: Nursing ImplicationsNursing Implications

IV administration:IV administration:

• Check IV site often for infiltrationCheck IV site often for infiltration

• Use clear IV solutionsUse clear IV solutions

• Use an infusion device/IV pumpUse an infusion device/IV pump

• Infuse agent slowly to avoid dangerous Infuse agent slowly to avoid dangerous cardiovascular effectscardiovascular effects

• Monitor cardiac rhythmMonitor cardiac rhythm

With chronic lung disease:With chronic lung disease:• Instruct patients to avoid factors that exacerbate Instruct patients to avoid factors that exacerbate

their condition.their condition.

• Encourage fluid intake Encourage fluid intake (up to 3000 mL per day) if permitted.(up to 3000 mL per day) if permitted.

• Educate about proper dosing and Educate about proper dosing and equipment care.equipment care.

Salmeterol is indicated for PREVENTION Salmeterol is indicated for PREVENTION of bronchospasms, not management of bronchospasms, not management

of acute symptoms.of acute symptoms.

• Overuse of nasal decongestants may cause rebound Overuse of nasal decongestants may cause rebound nasal congestion or ulcerations.nasal congestion or ulcerations.

• Avoid OTC or other medications because of possible Avoid OTC or other medications because of possible interactions.interactions.

• Administering two adrenergic agents together may Administering two adrenergic agents together may precipitate severe cardiovascular effects such as precipitate severe cardiovascular effects such as tachycardia or hypertension.tachycardia or hypertension.

• Inform patients taking inhaled isoproterenol that Inform patients taking inhaled isoproterenol that their sputum or saliva may turn pink.their sputum or saliva may turn pink.

Monitor for therapeutic effects Monitor for therapeutic effects (cardiovascular uses):(cardiovascular uses):

• Decreased edemaDecreased edema

• Increased urinary outputIncreased urinary output

• Return to normal vital signsReturn to normal vital signs

• Improved skin color and temperatureImproved skin color and temperature

• Increased LOCIncreased LOC

Monitor for therapeutic effects (asthma):Monitor for therapeutic effects (asthma):

• Return to normal respiratory rateReturn to normal respiratory rate

• Improved breath sounds, fewer ralesImproved breath sounds, fewer rales

• Increased air exchangeIncreased air exchange

• Decreased coughDecreased cough

• Less dyspneaLess dyspnea

• Improved blood gasesImproved blood gases

• Increased activity toleranceIncreased activity tolerance

Adrenergic-Blocking AgentsAdrenergic-Blocking Agents

• 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)

Adrenergic Blocking AgentsAdrenergic Blocking Agents

• Have the opposite effect of adrenergic Have the opposite effect of adrenergic agentsagents

• Also known asAlso known as

– adrenergic antagonists or sympatholyticsadrenergic antagonists or sympatholytics

• Sympatholytics inhibit—or LYSE—Sympatholytics inhibit—or LYSE—sympathetic neurotransmitterssympathetic neurotransmitters

(norepinephrine and epinephrine)(norepinephrine and epinephrine)

Classified by the type of adrenergic receptor Classified by the type of adrenergic receptor they blockthey block

• AlphaAlpha11 and alpha and alpha22 receptors receptors

• BetaBeta11 and beta and beta22 receptors receptors

Adrenergic-Blocking Agents: Adrenergic-Blocking Agents: Drug Effects and Therapeutic UsesDrug Effects and Therapeutic Uses

Ergot Alkaloids (Alpha-Blockers)Ergot Alkaloids (Alpha-Blockers)

• Constrict dilated arteries going to the brain Constrict dilated arteries going to the brain (carotid arteries)(carotid arteries)

• Used to treat vascular headaches (migraines)Used to treat vascular headaches (migraines)

• Stimulate uterine contractions by inducing Stimulate uterine contractions by inducing vasoconstrictionvasoconstriction

• Used to control postpartum bleedingUsed to control postpartum bleeding

Alpha-BlockersAlpha-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 decreased resistance to urinary outflow, thus reducing urinary obstruction and relieving effects reducing urinary obstruction and relieving effects of BPHof BPH

Alpha-BlockersAlpha-Blockers

• 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 epinephrine.epinephrine.

– Restores blood flow and prevents tissue necrosis.Restores blood flow and prevents tissue necrosis.

Adrenergic-Blocking Agents: Adrenergic-Blocking Agents: Side EffectsSide Effects

Alpha BlockersAlpha Blockers

Body SystemBody System Side/Adverse EffectsSide/Adverse Effects

CardiovascularCardiovascular Palpitations, orthostaticPalpitations, orthostatichypotension, tachycardia, hypotension, tachycardia, edema, dysrhythmias, chest painedema, dysrhythmias, chest pain

CNSCNS Dizziness, headache, Dizziness, headache, drowsiness,drowsiness,

anxiety, depression, vertigo,anxiety, depression, vertigo,weakness, numbness, fatigueweakness, numbness, fatigue

Alpha BlockersAlpha Blockers

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

OtherOther Incontinence, nose bleeding,Incontinence, nose bleeding,tinnitus, dry mouth, pharyngitis,tinnitus, dry mouth, pharyngitis,rhinitisrhinitis

Beta BlockersBeta Blockers

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

• Compete with norepinephrine and Compete with norepinephrine and epinephrineepinephrine

• Selective and nonselective beta blockersSelective and nonselective beta blockers

Beta ReceptorsBeta Receptors

BetaBeta11 Receptors Receptors

• Located primarily on the heartLocated primarily on the heart

• Beta blockers selective for these receptors Beta blockers selective for these receptors are called cardioselective beta blockersare called cardioselective beta blockers

Beta ReceptorsBeta Receptors

BetaBeta22 Receptors Receptors

• Located primarily on smooth muscles Located primarily on smooth muscles of bronchioles and blood vesselsof bronchioles and blood vessels

Nonspecific Beta BlockersNonspecific Beta Blockers

• Beta blockers that block both betaBeta blockers that block both beta11 and and betabeta22 receptors receptors

Beta Blockers: Mechanism of ActionBeta Blockers: Mechanism of Action

Cardioselective (Beta1)Cardioselective (Beta1)

• 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 decreasing myocardial oxygen demanddecreasing myocardial oxygen demand

Beta Blockers: Mechanism of ActionBeta Blockers: Mechanism of Action

Nonspecific (BetaNonspecific (Beta11 and Beta and Beta22))

• 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

Beta Blockers: Therapeutic UsesBeta Blockers: Therapeutic Uses

• Anti-angina:Anti-angina: decreases demand fordecreases demand formyocardial oxygenmyocardial oxygen

• Cardioprotective:Cardioprotective: inhibits stimulation byinhibits stimulation bycirculating circulating

catecholaminescatecholamines

• Class II antidysrhythmicClass II antidysrhythmic

Beta Blockers: Therapeutic UsesBeta Blockers: Therapeutic Uses

• AntihypertensiveAntihypertensive

• Treatment of migraine headachesTreatment of migraine headaches

• Glaucoma (topical use)Glaucoma (topical use)

Beta Blockers: Side EffectsBeta Blockers: Side Effects

BloodBlood Agranulocytosis, thrombocytopeniaAgranulocytosis, thrombocytopenia

CardiovascularCardiovascular AV block, bradycardia, congestiveAV block, bradycardia, congestiveheart failure, peripheral vascularheart failure, peripheral vascularinsufficiencyinsufficiency

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

Beta BlockersBeta Blockers

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

colitiscolitis

OtherOther Impotence, rash, alopecia,Impotence, rash, alopecia,bronchospasmsbronchospasms

Adrenergic Blocking Agents: Adrenergic Blocking Agents: Nursing ImplicationsNursing Implications

• Assess for allergies and history of COPD, Assess for allergies and history of COPD, hypotension, cardiac dysrhythmias, hypotension, cardiac dysrhythmias, bradycardia, CHF, or other cardiovascular bradycardia, CHF, or other cardiovascular problemsproblems

Any preexisting condition that might be Any preexisting condition that might be exacerbated by the use of these agents might exacerbated by the use of these agents might

be a CONTRAINDICATION to their use.be a CONTRAINDICATION to their use.

• Remember that alpha blockers may Remember that alpha blockers may precipitate hypotension.precipitate hypotension.

• Remember that beta blockers may Remember that beta blockers may precipitate bradycardia, hypotension, precipitate bradycardia, hypotension, heart block, CHF, and bronchoconstriction.heart block, CHF, and bronchoconstriction.

• Avoid OTC medications because of possible Avoid OTC medications because of possible interactions.interactions.

• 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 agentsNeuromuscular blocking agents

– Oral hypoglycemic agentsOral hypoglycemic agents

• Encourage patients to take medications Encourage patients to take medications as prescribed.as prescribed.

• These medications should never be These medications should never be stopped abruptly.stopped abruptly.

• Report constipation or the development of Report constipation or the development of any urinary hesitancy or bladder distention.any urinary hesitancy or bladder distention.

• Teach patients to change positions slowly to Teach patients to change positions slowly to prevent or minimize postural hypotension.prevent 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 stable.activities 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 occur.occur.

Beta Blocking Agents: Beta Blocking Agents: Nursing ImplicationsNursing Implications

• Rebound hypertension or chest pain may occur if Rebound hypertension or chest pain may occur if this medication is discontinued abruptly.this medication is discontinued abruptly.

• Patients should notify their physician if they become Patients should notify their physician if they become ill and unable to take medication.ill and unable to take medication.

• Inform patients that they may notice a decrease in Inform patients that they may notice a decrease in their tolerance for exercise; dizziness and fainting their tolerance for exercise; dizziness and fainting may occur with increased activity. Notify the may occur with increased activity. Notify the physician if these problems occur.physician if these problems occur.

Beta Blocking Agents: Beta Blocking Agents: Nursing ImplicationsNursing Implications

Patients should report the following to Patients should report the following to their physician:their physician:

• Weight gain of more than 2 pounds (1 kg) Weight gain of more than 2 pounds (1 kg) within a weekwithin a 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

Monitor for side effects, including:Monitor for side effects, including:

HypotensionHypotension FatigueFatigue

Tachycardia (alpha blockers)Tachycardia (alpha blockers) LethargyLethargy

BradycardiaBradycardia DepressionDepression

Heart blockHeart block InsomniaInsomnia

CHFCHF Vivid nightmaresVivid nightmares

Increased airway resistanceIncreased airway resistance

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

Alpha-Adrenergic BlockersAlpha-Adrenergic Blockers

1.1. Type of blockadeType of blockade Phenoxybenzamine – non-competitive; slow Phenoxybenzamine – non-competitive; slow onset and long duration. 2-stage blockade.onset and long duration. 2-stage blockade.

All the rest: competitive All the rest: competitive

2.2. SelectivitySelectivity Nonselective: Nonselective: Phenoxybenzamine and phentolamine alpha-1 Phenoxybenzamine and phentolamine alpha-1 selective: Prazosin, terazosin, others alpha-selective: Prazosin, terazosin, others alpha-2 selective: Yohimbine 2 selective: Yohimbine alpha/beta blockers: Labetalol alpha/beta blockers: Labetalol

3.3. Others: phenothiazines, tricyclic antidepressantsOthers: phenothiazines, tricyclic antidepressants

www.freelivedoctor.com

Phenoxybenzamine

Prazosin Yohimbine

EPIEPI + PhenoxybenzaminePhenoxybenzamine alone

Receptorsno longeravailable

[Agonist], mg/kg

Decrease in the maximal efficacy of Epi due to a decrease in the number of receptors

Pharmacological Effects -Pharmacological Effects -PhenoxybenxaminePhenoxybenxamine

1.1. Cardiovascular systemCardiovascular systemBlood pressure Blood pressure Cardiac Effects Cardiac Effects Organ Blood FlowOrgan Blood FlowCapillariesCapillaries

2.2. Central nervous systemCentral nervous system

3.3. Respiratory systemRespiratory system

Pharmacological Effects – cont’dPharmacological Effects – cont’d

4.4. Eye - miosisEye - miosis

5.5. GI tract – Increased motilityGI tract – Increased motility

6.6. Urinary bladder – decreased tone in Urinary bladder – decreased tone in sphinctersphincter

7.7. Metabolic effects – increased insulin Metabolic effects – increased insulin secretion secretion

Adverse effectsAdverse effects

• Postural hypotensionPostural hypotension

• TachycardiaTachycardia

• SedationSedation

• Nasal stuffinessNasal stuffiness

• MiosisMiosis

• Impotence (inhibits ejaculation)Impotence (inhibits ejaculation)

• Exercise care in hypovolemic patientsExercise care in hypovolemic patients

Imidazoline derivatives - Imidazoline derivatives - phentolaminephentolamine

• Many other effects including:Many other effects including:

• ParasympathomimeticParasympathomimetic

• Increased gastric acid secretionIncreased gastric acid secretion

• Cardiac stimulationCardiac stimulation

• Increased secretion from exocrine glands, such Increased secretion from exocrine glands, such as salivary, sweat, lacrimal, pancreaticas salivary, sweat, lacrimal, pancreatic

• Coronary artery disease and peptic ulcer relative Coronary artery disease and peptic ulcer relative contraindication to it.contraindication to it.

Alpha-1 selective blockersAlpha-1 selective blockersPrazosinPrazosin

• Less cardiac stimulation since it preserves Less cardiac stimulation since it preserves alpha-2 mediated negative feedback + other alpha-2 mediated negative feedback + other mechanismsmechanisms

• Used in congestive heart failure and in Used in congestive heart failure and in hypertension but tolerance develops with time, hypertension but tolerance develops with time, maybe due to fluid retention.maybe due to fluid retention.

• Adverse effects: First dose phenomenon.Adverse effects: First dose phenomenon.

• Favorable effect on plasma lipids: increase Favorable effect on plasma lipids: increase HDL/LDL ratioHDL/LDL ratio

ADR (µg/Kg)

1 10 100 5000.1

1 10 100 500

+PRAZOSIN

Effect of Adrenaline (ADR) on Blood Pressure and Heart Rate Before and After Prazosin

Alpha-2 selective blockersAlpha-2 selective blockersYohimbineYohimbine

• Cardiovascular effects – peripheral and Cardiovascular effects – peripheral and central effectscentral effects

• Blocks other receptors also – serotonin, Blocks other receptors also – serotonin, dopaminedopamine

• Increases ADH releaseIncreases ADH release

• Enhances sexual activity – aphrodisiacEnhances sexual activity – aphrodisiac

• Potential uses: depression, obesity, NIDDMPotential uses: depression, obesity, NIDDM

Ergot alkaloidsErgot alkaloids

• Interact with serotonin and dopamine Interact with serotonin and dopamine receptors alsoreceptors also

• Direct smooth muscle contractionDirect smooth muscle contraction

• Structure-activity relationshipsStructure-activity relationships

• Coronary vasoconstrictionCoronary vasoconstriction

• Toxicity: GI, vascular insufficiency –ergotismToxicity: GI, vascular insufficiency –ergotism

• Use in migraine and post-partumUse in migraine and post-partum

Therapeutic Uses ofTherapeutic Uses ofAlpha-Adrenergic BlockersAlpha-Adrenergic Blockers

• Hypertension - alpha-1 selectiveHypertension - alpha-1 selective

• Conditions associated with increased sympathetic activity Conditions associated with increased sympathetic activity – e.g. pheochromocytoma– e.g. pheochromocytoma

• Hemodynamic shockHemodynamic shock

• Peripheral vascular disease – Raynaud’sPeripheral vascular disease – Raynaud’s

• Congestive heart failureCongestive heart failure

• Benign prostatic hyperplasiaBenign prostatic hyperplasia

• Pulmonary hypertension – tolazolinePulmonary hypertension – tolazoline

• Yohimbine or intracavernous phentolamine+papaverine Yohimbine or intracavernous phentolamine+papaverine for impotencefor impotence

adrenergic blockers

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