drugs affecting the sympathetic nervous system
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Drugs Affecting the
Sympathetic NervousSystem
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Drugs Affecting the Sympathetic Nervous
System
NE
NE
NE
NE
NE NE
Involuntary Muscle
Membrane
Adrenergic nerve ending
Release
Metabolism Reuptake
MAO
Adrenergic Receptor
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Drugs Affecting the Sympathetic Nervous
System
Alpha
Receptors
Beta 2
Receptors
Beta 1
Receptors
Adrenergic
Receptors
Beta
Receptors
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Drugs Affecting the Sympathetic Nervous
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Alpha-adrenergic Receptors
Found predominantly on smooth muscle
membrane.
When stimulated by NE or EPI produce
contraction.
Produces vasoconstriction of most blood vessels.
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Drugs Affecting the Sympathetic Nervous
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Beta-adrenergic Receptors
Found on both cardiac and some smoothmuscle membranes.
In the heart, beta 1 receptorspredominates.
When stimulated by NE or EPI, theyincrease heart rate and force ofcontraction.
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Drugs Affecting the Sympathetic Nervous
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Beta-adrenergic Receptors
Found on smooth muscle in the bronchus andsmooth muscles of blood vessels supplyingmuscle and the heart.
Stimulated with EPI result in relaxation.
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Drugs Affecting the Sympathetic Nervous
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Beta-adrenergic Receptors
In smooth muscle, beta 2 receptors
predominates.
When stimulated by EPI, they produces musclerelaxation.
Found in smooth muscles of blood vessels
supplying skeletal muscle and the coronaryarteries.
Found on smooth muscle in the bronchial tree.
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Drugs Affecting the Sympathetic Nervous
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Beta 1
Receptors
Found on smooth
muscle in the heart
Increase heart rate and
force of contraction.
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Drugs Affecting the Sympathetic Nervous
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Beta 2
Receptors
Found on smooth muscle
of blood vessels supplying
skeletal muscle and the heart.
Found on smooth
muscle in the
bronchial tree.
Vasodilatation. Bronchodilation.
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Drugs Affecting the Sympathetic Nervous
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Sympatholytic
Drugs
Sympathomimetic
Drugs
Sympathetic
Drugs
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Drugs Affecting the Sympathetic Nervous
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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.
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Drugs Affecting the Sympathetic Nervous
System
Contraction of
Sphincter Muscles
GI tract Urinary Tract Eyes
Inhibits movement of
intestinal contents
Restricts passage
of urine.Mydriasis
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Drugs Affecting the Sympathetic Nervous
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Alpha-adrenergic Drugs
Clinical Indications
Hypotensive states
Decongestion
Pupillary dilation
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Adverse Effects
Hypertensive crisis
Cerebral hemorrhage
Cardiac arrhythmias
Irritation of the nasal sinuses or eye.
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Drugs Affecting the Sympathetic Nervous
System
Drug Main Use
Epinephrine To increase BP
Norepinephrine To increase BP
Pseudoephedrine Nasal decongestion
Tetrahydrozoline Ophthalmic decongestion
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Drugs Affecting the Sympathetic Nervous
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Beta-adrenergic Drugs
Stimulation of the heart
Bronchodilation
Relaxes uterine smooth muscle
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Drugs Affecting the Sympathetic Nervous
System
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.
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Drugs Affecting the Sympathetic Nervous
System
Epinephrine
DOC for allergic reactions
Use in combination with local anesthetics.
Used as a cardiac stimulant in emergencies.
Use in the treatment of asthma.
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Drugs Affecting the Sympathetic Nervous
System
Adverse Effects
CNS stimulationtremor, restlessness,
anxiety (beta effect)
Over-stimulation of the heart (beta 1 effect)
Lower blood pressure (beta 2 effect)
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Drugs Affecting the Sympathetic Nervous
System
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 moreBeta-1 effect.
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Drugs Affecting the Sympathetic Nervous
System
NE
NE
NE
NE
Tyrosine
NEDopamineDOPA
MAO
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Drugs Affecting the Sympathetic Nervous
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DOPAMINE
DOSE
RECEPTORS
STIMULATED
EFFECTS
Low dose Stimulate dopaminergicreceptors in the renal and
mesenteric blood vessels.
Increased renal blood flow andvasodilatation.
Moderate dose Stimulates beta-1
receptors in the heart.
Increase myocardial
contractility.
Higher dose Stimulate alpha-receptors Produces vasoconstriction.
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Drugs Affecting the Sympathetic Nervous
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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.
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Drugs Affecting the Sympathetic Nervous
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Alpha-adrenergic blocking drugs.
Clinical Indications
Treatment of hypertension.
Vasodilator in treatment of Raynauds disease.
Diagnosis of Pheochromocytoma.
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Drugs Affecting the Sympathetic Nervous
System
Alpha-adrenergic blocking drugs.
Adverse Effects
Constriction of pupils
Increased GI activity
Nasal congestion
Reflex tachycardia ( if BP is lowered too much).
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Drugs Affecting the Sympathetic Nervous
System
Drugs Main Use
Doxazosin Treatment of Hypertension
Prazosin Treatment of Hypertension
Phentolamine Diagnosis of pheochromocytoma.
Treatment of vascular disease.
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Drugs Affecting the Sympathetic Nervous
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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 ofcontraction.
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Drugs Affecting the Sympathetic Nervous
System
Selective Beta-1Non-selective
Beta-blocking
Drugs
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Nonselective Blockers Main Use
Labetalol Hypertension
Nadolol Hypertension, Angina Pectoris
Pindolol Hypertension
Propanolol Hypertension, Angina Pectoris,arrhythmhias, migraine
Timolol Hypertension, post myocardial
infarction.
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Selective Blockers Main Use
Acebutolol Hypertension, ventricular
arrhythmias.Atenolol Hypertension, Angina Pectoris
Bisoprolol Hypertension
Esmolol Supraventricular tachycardia
Metoprolol Hypertension, Angina Pectoris
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Propranolol
Decrease heart rate
Decrease force of contraction
Decrease rate of conduction
Resulting decrease in effort and work of the heartcauses a decrease in oxygen consumption.
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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 centralsympathetic activity.
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Drugs Affecting the Sympathetic Nervous
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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 therapyof beta blockers with other drugs that decrease
cardiac function (cardiac glycosides, anti-
arrhythmic drugs and calcium blockers).
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Adrenergic neuronal blockers
Drugs that interfere with the formation
and or storage of NE
Alpha-methyl dopa
Reserpine
Guanethidine
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Drugs Affecting the Sympathetic Nervous
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NE
NE
NE
NE
TyrosineNE
DopamineDOPA
Alpha-methyl dopa
MAO
Reserpine
Guanethidine
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Drugs Affecting the Sympathetic Nervous
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Drugs Mechanism of Action Main Use
Alpha-methyl dopa Blocks formation of
Dopamine
Treatment of
hypertension
Reserpine Depletes NE storage
granule
Treatment of
hypertension
Guanethidine Block release of NE
and depletes NE
storage granule
Treatment of
hypertension