Drugs affecting the_sympathetic_nervous_system

AUTONOMIC NERVOUS SYSTEM AGENTS

Nelia B. Perez RN, MSN

PCU – Mary Johnston College of Nursing

1. Drugs that stimulate the sympathetic nervous system are called

a. adrenergics

b. Cholinergics

c. Analeptics

d. benzodiazepines

2. The sympathetic neurotransmitters are norepinephrine and epinephrine.

a. true

b. false

3. These receptors are found predominantly in the smooth muscle membrane.

a. alpha adrenergic receptors

b. Alpha 2 adrenergic receptors

c. Beta adrenergic receptors

d. Beta2 adrenergic receptors

4. The most important clinical effect of this drug is contraction of smooth muscles.

a. beta adrenergic drugs

b. Anxiolitics

c. Alpha-adrenergic Drugs

b. Anticholinergics

• Most important clinical effect is contraction of smooth muscles.

5. A beta2 adrenergic drug which is primarily used as a bronchodilator.

a. Epinephrine

b. Norepinephrine

c. albuterol

d. ephedrine

6. When used as a Beta1 Adrenergic drug, it causes over-stimulation of the heart.

a. Norepinephrine

b. Epinephrine

c. Ephedrine

d. isoetharine

7. It is a Neurotransmitter in the brain and serves as a precursor in the synthesis of norepinephrine. a. Dopamineb. Dobutaminec. Epinephrined. Ephedrine

8. It antagonizes the effect of Norepinephrine and epinephrine which results in vasodilatation and thus decrease in BP.

a. Alpha-adrenergic blocking drugs

b. Alpha2-adrenergic blocking drugs

c. Beta-adrenergic blocking drugs

d. Beta2-adrenergic blocking drugs

9. It leads to a decrease in sympathetic response resulting in decrease heart rate and force of contraction.

a. Alpha-adrenergic blocking drugs

b. Alpha2-adrenergic blocking drugs

c. Beta-adrenergic blocking drugs

d. Beta2-adrenergic blocking drugs

10. Adrenergic neuronal blockers are those which

a. interfere with the formation and or storage of NE

b. Blocks the synthesis of epinephrine

c. Dilates blood vessels in hypertension

d. Serves as bronchodilators

Drugs Affecting the Sympathetic Nervous

System

Drugs Affecting the Sympathetic Nervous System

NE

NE

NE

NE

NE NE

Involuntary MuscleMembrane

Adrenergic nerve ending

Release

Metabolism Reuptake

MAO

Adrenergic Receptor


AlphaReceptors

Beta 2 Receptors

Beta 1Receptors

Adrenergic Receptors

BetaReceptors


Alpha-adrenergic Receptors

• Found predominantly on smooth muscle membrane.

• When stimulated by NE or EPI produce contraction.

• Produces vasoconstriction of most blood vessels.


Beta-adrenergic Receptors

• Found on both cardiac and some smooth muscle membranes.

• In the heart, beta 1 receptors predominates.

• When stimulated by NE or EPI, they increase heart rate and force of contraction.



• Found on smooth muscle in the bronchus and smooth muscles of blood vessels supplying muscle and the heart.

• Stimulated with EPI result in relaxation.



• In smooth muscle, beta 2 receptors predominates.

• When stimulated by EPI, they produces muscle relaxation.

• Found in smooth muscles of blood vessels supplying skeletal muscle and the coronary arteries.

• Found on smooth muscle in the bronchial tree.


Beta 1Receptors

Found on smooth muscle in the heart

Increase heart rate and force of contraction.


Beta 2 Receptors

Found on smooth muscleof blood vessels supplyingskeletal muscle and the heart.

Found on smoothmuscle in the bronchial tree.

Vasodilatation. Bronchodilation.


SympatholyticDrugs

SympathomimeticDrugs

SympatheticDrugs


SympathomimeticDrugs

Alpha-adrenergic Beta- adrenergic

Selective Beta 1Adrenergic.

Selective Beta 2Adrenergic.


Alpha-adrenergic Drugs

• NE prototype

• Most important clinical effect is contraction of smooth muscles.

• Vasoconstriction of most blood vessels leading to increase in blood pressure.

• Contraction of sphincter muscles.


Contraction of Sphincter Muscles

GI tract Urinary Tract Eyes

Inhibits movement ofintestinal contents

Restricts passage of urine.

Mydriasis


Alpha-adrenergic Drugs

Clinical Indications

• Hypotensive states

• Decongestion

• Pupillary dilation


Adverse Effects

• Hypertensive crisis

• Cerebral hemorrhage

• Cardiac arrhythmias

• Irritation of the nasal sinuses or eye.


Drug Main Use

Epinephrine To increase BP

Norepinephrine To increase BP

Pseudoephedrine Nasal decongestion

Tetrahydrozoline Ophthalmic decongestion


Beta-adrenergic Drugs

• Stimulation of the heart

• Bronchodilation

• Relaxes uterine smooth muscle


Drugs Classification Main Use

Epinephrine Alpha, Beta-1 and Beta-2

Vasopressor, Cardiac stimulant, bronchodilator.

Isoproterenol Beta-1 and Beta-2

Cardiac stimulant, bronchodilator.

Albuterol Beta-2 Bronchodilator.

Ritodrine Beta-2 Arrest preterm labor.


Epinephrine

• DOC for allergic reactions

• Use in combination with local anesthetics.

• Used as a cardiac stimulant in emergencies.

• Use in the treatment of asthma.


Adverse Effects

• CNS stimulation – tremor, restlessness, anxiety (beta effect)

• Over-stimulation of the heart (beta 1 effect)

• Lower blood pressure (beta 2 effect)


Dopamine

• Neurotransmitter in the brain.

• Precursor in the synthesis of NE

• Stimulates dopaminergic, beta-1 and alpha-receptors.

• Use as a drug.

• Dobutamine similar to dopamine but with more Beta-1 effect.


NE

NE

NE

NE

Tyrosine

NE

DopamineDOPA

MAO


DOPAMINE DOSE

RECEPTORS

STIMULATED

EFFECTS

Low dose Stimulate dopaminergic receptors in the renal and mesenteric blood vessels.

Increased renal blood flow and vasodilatation.

Moderate dose Stimulates beta-1 receptors in the heart.

Increase myocardial contractility.

Higher dose Stimulate alpha-receptors Produces vasoconstriction.


Alpha-adrenergic blocking drugs

• Binds to Alpha receptors

• Antagonizes the effects of NE and EPI

• Leads to a decrease in sympathetic response

• Resulting in vasodilatation and thus decrease in BP.


Alpha-adrenergic blocking drugs.

Clinical Indications

• Treatment of hypertension.

• Vasodilator in treatment of Raynaud’s disease.

• Diagnosis of Pheochromocytoma.


Alpha-adrenergic blocking drugs.

Adverse Effects

• Constriction of pupils

• Increased GI activity

• Nasal congestion

• Reflex tachycardia ( if BP is lowered too much).


Drugs Main Use

Doxazosin Treatment of Hypertension

Prazosin Treatment of Hypertension

Phentolamine Diagnosis of pheochromocytoma.

Treatment of vascular disease.


Beta-adrenergic blocking drugs.

• Binds to beta receptors

• Antagonizes the effects of NE and EPI

• Leads to a decrease in sympathetic response.

• Resulting in decrease heart rate and force of contraction.


Selective Beta-1Non-selective

Beta-blockingDrugs


Nonselective Blockers Main Use

Labetalol Hypertension

Nadolol Hypertension, Angina Pectoris

Pindolol Hypertension

Propanolol Hypertension, Angina Pectoris, arrhythmhias, migraine

Timolol Hypertension, post myocardial infarction.


Selective Blockers Main Use

Acebutolol Hypertension, ventricular arrhythmias.

Atenolol Hypertension, Angina Pectoris

Bisoprolol Hypertension

Esmolol Supraventricular tachycardia

Metoprolol Hypertension, Angina Pectoris


Propranolol

• Decrease heart rate

• Decrease force of contraction

• Decrease rate of conduction

• Resulting decrease in effort and work of the heart causes a decrease in oxygen consumption.


• Oral and iv preparation

• Drug is carried directly to the liver by the portal system.

• Significant first pass metabolism.

• Lipid soluble and passes into the brain.

• Causes CNS sedation, depression and decreased central sympathetic activity.


• Used in the treatment of angina, and various cardiac arrhythmia.

• Adverse effects include nausea, vomiting and diarrhea, bradycardia with resulting reduced cardiac function, bronchoconstriction.

• Most serious drug interactions involve therapy of beta blockers with other drugs that decrease cardiac function (cardiac glycosides, anti-arrhythmic drugs and calcium blockers).


Adrenergic neuronal blockers

• Drugs that interfere with the formation and or storage of NE

• Alpha-methyl dopa

• Reserpine

• Guanethidine


NE

NE

NE

NE

Tyrosine

NE

DopamineDOPA

Alpha-methyl dopa

MAO

Reserpine

Guanethidine


Drugs Mechanism of Action Main Use

Alpha-methyl dopa Blocks formation of Dopamine

Treatment of hypertension

Reserpine Depletes NE storage granule


Guanethidine Block release of NE and depletes NE storage granule


ANS - Adrenergic Drugs 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; include postural blood pressure and pulse

Follow administration guidelines carefully

Intravenous administration Check IV site often for infiltration Use clear IV solutions / Use an infusion pump Infuse drug slowly to avoid dangerous cardiovascular effects Monitor cardiac rhythm

ANS - Adrenergic Drugs Nursing Implications (cont’d)

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, use of equipment (MDI, spacer, nebulizer), and equipment care


Salmeterol is indicated for prevention of bronchospasms, not management of acute symptoms Overuse of nasal decongestants may cause rebound nasal congestion or ulcerations

Avoid OTC or other medications because of possible interactions

Administering two adrenergic drugs together may precipitate severe cardiovascular effects such as tachycardia or hypertension


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

(bronchospasm/asthma):

• Return to normal respiratory rate• Improved breath sounds, fewer rales • Increased air exchange• Decreased cough• Less dyspnea• Improved blood gases• Increased activity tolerance

Let’s take a break!

Drugs affecting the_sympathetic_nervous_system

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