Transcript Drugs Affecting Autonomic Nervous System 1

Drugs Affecting Autonomic Nervous
System 1
Lecture objectives
 Identify the anatomy of nervous
system.
 Identify the drugs that effect ANS
Nervous System Divisions
Nervous System Overview
 Nervous System
 Brain
 Spinal cord
 Nerves
 Functions of nervous system
 Regulates and coordinates all body
activities
 Center of all mental activity, including
thought, learning, and memory
Nervous System Divisions
 Central Nervous System (CNS)
 Brain
 Spinal Cord
 Processes and stores sensory and motor
information
 Controls consciousness
 Peripheral Nervous System (PNS)
 12 Pairs of Cranial Nerves
 31 Pairs of Spinal Nerves
 Transmits sensory and motor impulses back and
forth between CNS and rest of body
Peripheral Nervous System
 Somatic Nervous System (SNS)
 Provides voluntary control over skeletal
muscle contractions
 Autonomic Nervous System (ANS)
 Provides involuntary control over
smooth muscle, cardiac muscle, and
glandular activity and secretions in
response to the commands of the
central nervous system
Autonomic Nervous System
 Sympathetic nerves
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Increase heart rate
Constrict blood vessels
Raise blood pressure
Fight-or-flight response
 Parasympathetic nerves
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Slow heart rate
Increase peristalsis of intestines
Increase glandular secretions
Relax sphincters
Catecholamines
 Substances that can produce a sympathomimetic
response
1. Endogenous:
Dopamine (Dopaminergic) epinephrine &
norepinephrine (Adrenegeric)
2. Synthetic:
isoproterenol, dobutamine, phenylephrine
Fight or Flight Response:
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These catecholamine hormones facilitate immediate physical
reactions These include the following:
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Acceleration of heart and lung action･Inhibition of stomach
and intestinal action
Constriction of blood vessels in many parts of the body
Dilation of blood vessels for muscles
Inhibition of tear glands and salivation
Dilation of pupil
Relaxation of bladder
Inhibition of erection
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Dopaminergic Receptors
 An additional adrenergic receptor
 Stimulated by dopamine
 Causes dilation of the following
blood vessels, resulting in
INCREASED blood flow
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Renal
Mesenteric
Coronary
Cerebral
Adrenergic Agents
 Drugs that stimulate the sympathetic
nervous system (SNS)
Also known as:
 adrenergic agonists or sympathomimetics
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
Types of -adrenergic receptor
 -adrenergic receptors are adrenergic receptors that respond
to norepinephrine and to such blocking agents as
phenoxybenzamine.
 They are subdivided into two types:
 1, found in smooth muscle, heart, and liver, with effects
including vasoconstriction, intestinal relaxation, uterine
contraction and pupillary dilation,
 2, found in platelets, vascular smooth muscle, nerve termini,
and pancreatic islets, with effects including platelet aggregation,
vasoconstriction, and inhibition of norepinephrine release and of
insulin secretion.
-receptor types
 -adrenergic receptors respond particularly to
epinephrine and to such blocking agents as
propranolol.
 There are three known types of beta receptor,
designated β1, β2 and β3.
 β1-Adrenergic receptors are located mainly in the
heart.
 β2-Adrenergic receptors are located mainly in the
lungs, gastrointestinal tract, liver, uterus, vascular
smooth muscle, and skeletal muscle.
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β3-receptors are located in fat cells.
What do the receptors do?
Activation of  receptors leads to smooth
muscle contraction
Activation of 2 receptors leads to smooth
muscle relaxation
Activation of 1 receptors leads to smooth
muscle contraction (especially in heart)
Clinical Utility of drugs which affect the adrenergic nervous
system:
a.
Agonists of the 2 receptors are used in the
treatment of asthma (relaxation of the smooth muscles of
the bronchi)
b.
Antagonists of the 1 receptors are used in the
treatment of hypertension and angina (slow heart and
reduce force of contraction)
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Antagonists of the 1 receptors are known to
cause lowering of the blood pressure (relaxation of smooth
muscle and dilation of the blood vessels)
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) automaticity
Adrenergic Agents:
Therapeutic Uses
1. Anorexiants: adjuncts to diet in the short-term
management of obesity
Examples:
benzaphetamine
phentermine
dextroamphetamine
Dexedrine
2.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
Adrenergic Agents: Therapeutic Uses
Reduction of intraocular pressure and mydriasis (pupil
dilation): treatment of
open-angle glaucoma
Examples: epinephrine and dipivefrin
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4. 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
5. Ophthalmic
relieving conjunctival congestion.
Examples:epinephrine naphazoline
phenylephrine
tetrahydrozoline
6. Vasoactive sympathomimetics also called cardio selective
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:
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
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.
Adrenergic Agents: Nursing Implications
 Overuse of nasal decongestants may cause
rebound nasal congestion or ulcerations.
 Monitor for therapeutic effects
(cardiovascular uses):
 Decreased edema
 Increased urinary output
 Return to normal vital signs
 Improved skin color and temperature
 Increased LOC
Adrenergic Agents: Nursing Implications
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Monitor for therapeutic effects (asthma):
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)
 Have the opposite effect of adrenergic agents
 Also known as
 adrenergic antagonists or sympatholytics
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
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
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Beta Blockers: Therapeutic
Uses
1. Anti-angina:decreases demand for myocardial
oxygen
2. Cardioprotective:inhibits stimulation by
circulating catecholamines
3. Class II antidysrhythmic
4. Antihypertensive
5. Treatment of migraine headaches
6. Glaucoma (topical use)
Adrenergic Blocking Agents:
Nursing Implications
 Assess for allergies and history of COPD,
hypotension, cardiac dysrhythmias,
bradycardia, CHF, or other cardiovascular
problems
 Remember that alpha blockers may
precipitate hypotension.
 Remember that beta blockers may
precipitate bradycardia, hypotension,
heart block, CHF, and bronchoconstriction.
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Encourage patients to take medications
as prescribed.
These medications should never be stopped abruptly.
Report constipation or the development of any urinary or
bladder distention.
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:
1. Weight gain of more than 2 pounds (1 kg)
within a week
2. Edema of the feet or ankles
3. Shortness of breath
4. Excessive fatigue or weakness
5. Syncope or dizziness
Monitor for side effects, including:
1. Hypotension
2. Fatigue
3. Tachycardia (alpha blockers)
4. Lethargy
5. Bradycardia
6. Depression
7. Heart block
8. Insomnia
9. CHF
10. nightmares
11. Increased airway resistance
QUESTION?