Download Adrenergic Agents. Adrenergic Blocking Agents

Adrenergic agemts
Learning Objectives
• Understand the central and peripheral
nervous systems, their functions, and their
relationship to drugs.
• Become aware of the role of
neurotransmitters.
• Learn how adrenergic drugs affect body
systems and where they work in the body.
Learning Objectives
• Define the action of neuromuscular blocking
agents in reducing muscle activity.
• Distinguish between narcotic and nonnarcotic
analgesia.
• Become familiar with the various types of
agents for migraine headaches.
Divisions of the Nervous System
• Central Nervous System
– Brain
– Spinal cord
• Peripheral Nervous System
– Nerves
– Sense organs
Divisions of the Nervous System
• Central Nervous System
• Peripheral Nervous System
Divisions of the Nervous System
• Central Nervous System
• Peripheral Nervous System
– Somatic Nervous System
– Autonomic Nervous System
Divisions of the Nervous System
• Central Nervous System
• Peripheral Nervous System
– Somatic Nervous System
Voluntary action: skeletal muscle contraction and
movement
– Autonomic Nervous System
Involuntary activities: respiration, circulation,
digestion, sweating
Autonomic Nervous System
Review
The nervous system has two
components. What are they?
Review
The nervous system has two components. What
are they?
Answer
– Central nervous system (CNS)
– Peripheral nervous system (PNS)
Major Neurotransmitters
•
•
•
•
•
Acetylcholine
GABA
Dopamine
Epinephrine
Serotonin
Major Neurotransmitters
• Acetylcholine (ACh)
– Smooth muscle, cardiac muscle, and
exocrine glands
– Anticholinergics block ACh receptors
•
•
•
•
GABA
Dopamine
Epinephrine
Serotonin
Major Neurotransmitters
• Acetylcholine
• GABA (gamma-aminobutyric acid)
Regulates message delivery system of
the brain
• Dopamine
• Epinephrine
• Serotonin
Major Neurotransmitters
• Acetylcholine
• GABA
• Dopamine
Acts on the CNS and kidneys
• Epinephrine
• Serotonin
Major Neurotransmitters
• Acetylcholine
• GABA
• Dopamine
• Epinephrine
– Acts on cardiac and bronchodilator
receptors
– Known as Adrenaline
• Serotonin
Major Neurotransmitters
•
•
•
•
Acetylcholine
GABA
Dopamine
Epinephrine
• Serotonin
– Acts on smooth muscle and gastric mucosa
(causes vasoconstriction)
– Emotional responses: depression, anxiety
Communication by
Neurotransmitters
Neurotransmitters are released from one
axon and received by another neuron’s
dendrites.
Discussion
What are three important
types of receptors in the study
of drugs?
Discussion
What are three important types of
adrenergic receptors in the study of drugs?
Answer
– Alpha
– Beta-1
– Beta-2
Types of Receptors
• Alpha
Vasoconstriction, raise BP
• Beta-1
Heart stimulation
• Beta-2
Vasodilation and bronchodilation
Drugs Affecting The
Autonomic Nervous
System
Adrenergic Agents and
Adrenergic-Blocking Agents
The Sympathetic Nervous
System
in Relationship to the Entire
Nervous System
Adrenergic Agents
• Drugs that stimulate the sympathetic
nervous system (SNS)
Adrenergic Agents
Also known as
• adrenergic agonists or sympathomimetics
Adrenergic Agents
Mimic the effects of the SNS
neurotransmitters:
• norepinephrine (NE) and epinephrine (EPI)
Adrenergic Receptors
• Located throughout the body
• Are receptors for the sympathetic
neurotransmitters
Alpha-adrenergic receptors: respond to NE
Beta-adrenergic receptors: respond to EPI
Alpha-Adrenergic Receptors
• Divided into alpha1 and alpha2 receptors
• Differentiated by their location on nerves
Alpha1-Adrenergic Receptors
• Located on postsynaptic effector cells
(the cell, muscle, or organ that the nerve
stimulates)
Alpha2-Adrenergic Receptors
• Located on presynaptic nerve terminals
(the nerve that stimulates the effector cells)
• Control the release of neurotransmitters
The predominant alphaadrenergic agonist responses are:
• Vasoconstriction and CNS stimulation
Beta-Adrenergic Receptors
All are located on postsynaptic effector cells
• Beta1-adrenergic receptors—located primarily
in the heart
• Beta2-adrenergic receptors—located in smooth
muscle of the bronchioles, arterioles, and visceral
organs
The beta-adrenergic agonist
response results in:
• Bronchial, GI, and uterine smooth muscle
relaxation
• Glycogenolysis
• Cardiac stimulation
Dopaminergic Receptors
• An additional adrenergic receptor
• Stimulated by dopamine
• Causes dilation of the following blood vessels,
resulting in INCREASED blood flow
–
–
–
–
Renal
Mesenteric
Coronary
Cerebral
Adrenergic Receptor Responses
to Stimulation
LOCATION
Cardiovascular
Blood vessels
Cardiac muscle
AV Node
SA Node
RECEPTOR
RESPONSE
alpha1 and beta2 Constriction /
dilation
beta1
Increased
contractility
beta1
Increased
heart rate
beta1
Increased
heart rate
Adrenergic Receptor Responses
to Stimulation
LOCATION
RECEPTOR
RESPONSE
Gastrointestinal
Muscle
beta2
Sphincters
alpha1
Decreased
motility
Constriction
Adrenergic Receptor Responses
to Stimulation
LOCATION
Genitourinary
Bladder
sphincter
Penis
Uterus
RECEPTOR
RESPONSE
alpha1
Constriction
alpha1
Ejaculation
alpha1 and beta2 Contraction/
relaxation
Adrenergic Receptor Responses
to Stimulation
LOCATION
Respiratory
Bronchial
muscles
RECEPTOR
RESPONSE
beta2
Dilation/relaxation
Catecholamines
Substances that can produce a
sympathomimetic response
Endogenous:
• epinephrine, norepinephrine,dopamine
Synthetic:
• isoproterenol, dobutamine, phenylephrine
Adrenergic Agents
Mechanism of Action
Direct-acting sympathomimetic:
• Binds directly to the receptor and causes a
physiologic response
Direct-Acting Sympathomimetics
Adrenergic Agents
Mechanism of Action
Indirect-acting sympathomimetic:
• Causes the release of catecholamine from the
storage sites (vesicles) in the nerve endings
• The catecholamine then binds to the receptors and
causes a physiologic response
Indirect-Acting
Sympathomimetics
Adrenergic Agents
Mechanism of Action
Mixed-acting sympathomimetic:
• Directly stimulates the receptor by binding
to it
AND
• Indirectly stimulates the receptor by causing
the release of stored neurotransmitters from
the vesicles in the nerve endings
Mixed-Acting
Sympathomimetics
Drug Effects of Adrenergic
Agents
Stimulation of alpha-adrenergic receptors on
smooth muscles results in:
•
•
•
•
•
•
Vasoconstriction of blood vessels
Relaxation of GI smooth muscles
Contraction of the uterus and bladder
Male ejaculation
Decreased insulin release
Contraction of the ciliary muscles of the eye
(dilated pupils)
Drug Effects of Adrenergic
Agents
Stimulation of beta2-adrenergic receptors on
the airways results in:
• Bronchodilation (relaxation of the bronchi)
• Uterine relaxation
• Glycogenolysis in the liver
Drug Effects of Adrenergic
Agents
Stimulation of beta1-adrenergic receptors on
the myocardium, AV node, and SA node
results in CARDIAC STIMULATION:
• Increased force of contraction
(positive inotropic effect)
• Increased heart rate
(positive chronotropic effect)
• Increased conduction through the AV node
(positive dromotropic effect)
Adrenergic Agents:
Therapeutic Uses
• Anorexiants: adjuncts to diet in the
short-term management of obesity
Examples:
benzphetamine
phentermine
dextroamphetamine
Dexedrine
Adrenergic Agents:
Therapeutic Uses
Bronchodilators: treatment of asthma and
bronchitis
• Agents that stimulate beta2-adrenergic receptors
of bronchial smooth muscles causing relaxation
Examples:
albuterol
ephedrine
epinephrine
isoetharine
isoproterenol levalbuterol
metaproterenol
salmeterol
terbutaline
• These agents may also affect uterine and vascular
smooth muscles.
Adrenergic Agents:
Therapeutic Uses
• Reduction of intraocular pressure and
mydriasis (pupil dilation): treatment of
open-angle glaucoma
Examples:
epinephrine and dipivefrin
Adrenergic Agents:
Therapeutic Uses
Nasal decongestant:
• Intranasal (topical) application causes constriction
of dilated arterioles and reduction of nasal blood
flow, thus decreasing congestion.
Examples:
epinephrine
ephedrine
naphazoline
phenylephrine
tetrahydrozoline
Adrenergic Agents:
Therapeutic Uses
Ophthalmic
• Topical application to the eye surface affects
the vasculature of the eye, stimulating alpha
receptors on small arterioles, thus relieving
conjunctival congestion.
Examples:
epinephrine
phenylephrine
naphazoline
tetrahydrozoline
Adrenergic Agents:
Therapeutic Uses
Vasoactive sympathomimetics (pressors,
inotropes), also called cardioselective
sympathomimetics
• Used to support the heart during cardiac failure
or shock.
Examples:
dobutamine
dopamine
ephedrine
epinephrine
fenoldopam
isoproterenol
methoxamine norepinephrine
phenylephrine
Adrenergic Agents: Side Effects
Alpha-Adrenergic Effects
• CNS:
– headache, restlessness, excitement, insomnia, euphoria
• Cardiovascular:
– palpitations (dysrhythmias), tachycardia,
vasoconstriction, hypertension
• Other:
– anorexia, dry mouth, nausea, vomiting, taste changes
(rare)
Adrenergic Agents: Side Effects
Beta-Adrenergic Effects
• CNS:
– mild tremors, headache, nervousness, dizziness
• Cardiovascular:
– increased heart rate, palpitations (dysrhythmias),
fluctuations in BP
• Other:
– sweating, nausea, vomiting, muscle cramps
Adrenergic Agents: Interactions
• Anesthetic agents
• Tricyclic antidepressants
• MAOIs
• Antihistamines
• Thyroid preparations
• Antihypertensives
• Will directly antagonize another adrenergic
agent, resulting in reduced effects
Adrenergic Agents:
Nursing Implications
• Assess for allergies and history of hypertension,
cardiac dysrhythmias, or other cardiovascular
disease.
• Assess renal, hepatic, and cardiac function before
treatment.
• Perform baseline assessment of vital signs,
peripheral pulses, skin color, temperature, and
capillary refill. Include postural blood pressure
and pulse.
• Follow administration guidelines carefully.
Adrenergic Agents:
Nursing Implications
IV administration:
•
•
•
•
Check IV site often for infiltration
Use clear IV solutions
Use an infusion device/IV pump
Infuse agent slowly to avoid dangerous
cardiovascular effects
• Monitor cardiac rhythm
Adrenergic Agents:
Nursing Implications
With chronic lung disease:
• Instruct patients to avoid factors that exacerbate
their condition.
• Encourage fluid intake
(up to 3000 mL per day) if permitted.
• Educate about proper dosing and
equipment care.
Salmeterol is indicated for PREVENTION
of bronchospasms, not management
of acute symptoms.
Adrenergic Agents:
Nursing Implications
• Overuse of nasal decongestants may cause
rebound nasal congestion or ulcerations.
• Avoid OTC or other medications because of
possible interactions.
• Administering two adrenergic agents together
may precipitate severe cardiovascular effects such
as tachycardia or hypertension.
• Inform patients taking inhaled isoproterenol that
their sputum or saliva may turn pink.
Adrenergic Agents:
Nursing Implications
Monitor for therapeutic effects
(cardiovascular uses):
•
•
•
•
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Decreased edema
Increased urinary output
Return to normal vital signs
Improved skin color and temperature
Increased LOC
Adrenergic Agents:
Nursing Implications
Monitor for therapeutic effects (asthma):
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•
•
•
•
•
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Return to normal respiratory rate
Improved breath sounds, fewer rales
Increased air exchange
Decreased cough
Less dyspnea
Improved blood gases
Increased activity tolerance
Adrenergic-Blocking Agents
• Bind to adrenergic receptors, but inhibit or
block stimulation of the sympathetic
nervous system (SNS)
Adrenergic Blocking Agents
• Have the opposite effect of adrenergic
agents
• Also known as
– adrenergic antagonists or sympatholytics
Adrenergic Blocking Agents
• Sympatholytics inhibit—or LYSE—
sympathetic neurotransmitters
(norepinephrine and epinephrine)
Adrenergic Blocking Agents
Classified by the type of adrenergic receptor
they block
• Alpha1 and alpha2 receptors
• Beta1 and beta2 receptors
Alpha-Blocker Mechanisms
Adrenergic-Blocking Agents:
Drug Effects and Therapeutic
Uses
Ergot Alkaloids (Alpha-Blockers)
• Constrict dilated arteries going to the brain
(carotid arteries)
• Used to treat vascular headaches (migraines)
• Stimulate uterine contractions by inducing
vasoconstriction
• Used to control postpartum bleeding
Adrenergic-Blocking Agents:
Drug Effects and Therapeutic
Uses
Alpha-Blockers
• Cause both arterial and venous dilation, reducing
peripheral vascular resistance and BP
• Used to treat hypertension
• Effect on receptors on prostate gland and bladder
decreased resistance to urinary outflow, thus
reducing urinary obstruction and relieving effects
of BPH
Adrenergic-Blocking Agents:
Drug Effects and Therapeutic
Uses
Alpha-Blockers
• Phentolamine
– Quickly reverses the potent vasoconstrictive effects of
extravasated vasopressors such as norepinephrine or
epinephrine.
– Restores blood flow and prevents tissue necrosis.
Adrenergic-Blocking Agents:
Side Effects
Alpha Blockers
Body System
Side/Adverse Effects
Cardiovascular
Palpitations, orthostatic
hypotension, tachycardia,
edema, dysrhythmias, chest
pain
CNS
Dizziness, headache, drowsiness,
anxiety, depression, vertigo,
weakness, numbness, fatigue
Adrenergic-Blocking Agents:
Side Effects
Alpha Blockers
Body System
Side/Adverse Effects
Gastrointestinal
Nausea, vomiting, diarrhea,
constipation, abdominal pain
Other
Incontinence, nose bleeding,
tinnitus, dry mouth, pharyngitis,
rhinitis
Beta Blockers
• Block stimulation of beta receptors in
the SNS
• Compete with norepinephrine and
epinephrine
• Selective and nonselective beta blockers
Beta Receptors
Beta1 Receptors
• Located primarily on the heart
• Beta blockers selective for these receptors
are called cardioselective beta blockers
Beta Receptors
Beta2 Receptors
• Located primarily on smooth muscles
of bronchioles and blood vessels
Nonspecific Beta Blockers
• Beta blockers that block both beta1 and
beta2 receptors
Beta Blockers: Mechanism of
Action
Cardioselective (Beta1)
•
•
•
•
Decreases heart rate
Prolongs SA node recovery
Slows conduction rate through the AV node
Decreases myocardial contractility, thus
decreasing myocardial oxygen demand
Beta Blockers: Mechanism of
Action
Nonspecific (Beta1 and Beta2)
• Effects on heart:
• Bronchioles:
• Blood vessels:
Same as cardioselective
Constriction, resulting in
narrowing of airways and
shortness of breath
Vasoconstriction
Beta Blockers: Therapeutic Uses
• Anti-angina:
• Cardioprotective:
catecholamines
• Class II antidysrhythmic
decreases demand for
myocardial oxygen
inhibits stimulation by
circulating
Beta Blockers: Therapeutic Uses
• Antihypertensive
• Treatment of migraine headaches
• Glaucoma (topical use)
Beta Blockers: Side Effects
Body System
Side/Adverse Effects
Blood
Agranulocytosis,
thrombocytopenia
Cardiovascular
congestive
AV block, bradycardia,
heart failure, peripheral vascular
insufficiency
CNS
Dizziness, mental depression,
lethargy, hallucinations
Adrenergic-Blocking Agents:
Side Effects
Beta Blockers
Body System
Gastrointestinal
Side/Adverse Effects
Nausea, dry mouth, vomiting,
diarrhea, cramps, ischemic
colitis
Other
Impotence, rash, alopecia,
bronchospasms
Adrenergic Blocking Agents:
Nursing Implications
• Assess for allergies and history of COPD,
hypotension, cardiac dysrhythmias,
bradycardia, CHF, or other cardiovascular
problems
Any preexisting condition that might be
exacerbated by the use of these agents might
be a CONTRAINDICATION to their use.
Adrenergic Blocking Agents:
Nursing Implications
• Remember that alpha blockers may
precipitate hypotension.
• Remember that beta blockers may
precipitate bradycardia, hypotension,
heart block, CHF, and bronchoconstriction.
Adrenergic Blocking Agents:
Nursing Implications
• Avoid OTC medications because of possible
interactions.
• Possible drug interactions may occur with:
–
–
–
–
–
Antacids (aluminum hydroxide type)
Antimuscarinics/anticholinergics
Diuretics and cardiovascular drugs
Neuromuscular blocking agents
Oral hypoglycemic agents
Adrenergic Blocking Agents:
Nursing Implications
• Encourage patients to take medications
as prescribed.
• These medications should never be
stopped abruptly.
• Report constipation or the development of
any urinary hesitancy or bladder distention.
Adrenergic Blocking Agents:
Nursing Implications
• Teach patients to change positions slowly to
prevent or minimize postural hypotension.
• Avoid caffeine (excessive irritability).
• Avoid alcohol ingestion and hazardous
activities until blood levels become stable.
• Patients should notify their physician if
palpitations, dyspnea, nausea, or vomiting
occur.
Beta Blocking Agents:
Nursing Implications
• Rebound hypertension or chest pain may occur if
this medication is discontinued abruptly.
• Patients should notify their physician if they
become ill and unable to take medication.
• Inform patients that they may notice a decrease in
their tolerance for exercise; dizziness and fainting
may occur with increased activity. Notify the
physician if these problems occur.
Beta Blocking Agents:
Nursing Implications
Patients should report the following to
their physician:
• Weight gain of more than 2 pounds (1 kg)
within a week
• Edema of the feet or ankles
• Shortness of breath
• Excessive fatigue or weakness
• Syncope or dizziness
Adrenergic Blocking Agents:
Nursing Implications
Monitor for side effects, including:
Hypotension
Tachycardia (alpha blockers)
Bradycardia
Heart block
CHF
Increased airway resistance
Fatigue
Lethargy
Depression
Insomnia
Vivid nightmares
Adrenergic Blocking Agents:
Nursing Implications
Monitor for therapeutic effects
• Decreased chest pain in patients with angina
• Return to normal BP and P
• Other specific effects, depending on the use