lecture_3_drugs_affecting_autonomic_nervous_system_1.ppt

Drugs Affecting Autonomic Nervous
System 1

Lecture objectives
 Identify the anatomy of nervous
system.
 Identify the drugs that effect ANS

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

 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
Nervous System Divisions

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

 Sympathetic nerves
 Increase heart rate
 Constrict blood vessels
 Raise blood pressure
 Fight-or-flight response
 Parasympathetic nerves
 Slow heart rate
 Increase peristalsis of intestines
 Increase glandular secretions
 Relax sphincters
Autonomic Nervous System

Catecholamines
 Substances that can produce a sympathomimetic
response
1. Endogenous:
Dopamine (Dopaminergic) epinephrine &
norepinephrine (Adrenegeric)
2. Synthetic:
isoproterenol, dobutamine, phenylephrine

Fight or Flight Response:
 These catecholamine hormones facilitate immediate physical
reactions These include the following:
 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

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 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.
 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)
c. 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)

 Stimulation of beta2-adrenergic
receptors on the airways results in:
 Bronchodilation (relaxation of the
bronchi)
 Uterine relaxation
 Glycogenolysis in the liver

 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
3. Reduction of intraocular pressure and mydriasis (pupil
dilation): treatment of
open-angle glaucoma
Examples: epinephrine and dipivefrin
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.

 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

 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

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:
 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.

 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:
 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

lecture_3_drugs_affecting_autonomic_nervous_system_1.ppt

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