This document summarizes information about autonomic drugs and the autonomic nervous system. It discusses how the autonomic nervous system is divided into the parasympathetic and sympathetic nervous systems, which often have opposing effects. It describes the pharmacology of cholinergic, anticholinergic, and adrenergic drugs, including their effects, uses, adverse reactions, and contraindications. Specifically, it provides details on how these drugs act on organ systems like the cardiovascular, gastrointestinal, and respiratory systems.

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Chapter 5Chapter 5
Autonomic DrugsAutonomic Drugs

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Autonomic PharmacologyAutonomic Pharmacology
 Autonomic Nervous SystemAutonomic Nervous System
 This system is divided into two separateThis system is divided into two separate
systems.systems.
 These systems are called the parasympatheticThese systems are called the parasympathetic
nervous system and the sympathetic nervousnervous system and the sympathetic nervous
system.system.
 These systems often produce opposite effects.These systems often produce opposite effects.
 Drugs in this group are designed to eitherDrugs in this group are designed to either
enhance or mimic the autonomic nervous systemenhance or mimic the autonomic nervous system
or to block the effects of the neurotransmitters ator to block the effects of the neurotransmitters at
their receptor sites.their receptor sites.
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Autonomic Nervous SystemAutonomic Nervous System
 Parasympathetic Nervous SystemParasympathetic Nervous System
 This system is concerned with theThis system is concerned with the
conservation of the body processes.conservation of the body processes.
 Its main neurotransmitter is acetylcholine.Its main neurotransmitter is acetylcholine.
 Its receptors are muscarinic, nicotinic, and theIts receptors are muscarinic, nicotinic, and the
somatic-skeletal muscles.somatic-skeletal muscles.
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Autonomic Nervous SystemAutonomic Nervous System
 Sympathetic Nervous SystemSympathetic Nervous System
 This nervous system is designed to cope withThis nervous system is designed to cope with
emergency situations.emergency situations.
 This is commonly known as the “fright or flight”This is commonly known as the “fright or flight”
response.response.
 Its neurotransmitters are epinephrine andIts neurotransmitters are epinephrine and
norepinephrine.norepinephrine.
 Its receptors are theIts receptors are the αα andand ββ receptors.receptors.
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Autonomic PharmacologyAutonomic Pharmacology
 Cholinergic or Parasympathomimetic DrugsCholinergic or Parasympathomimetic Drugs
 These drugs are classified as either direct or indirectThese drugs are classified as either direct or indirect
acting agents.acting agents.
 Direct acting drugs act directly on theDirect acting drugs act directly on the
parasympathetic receptors.parasympathetic receptors.
 Indirect acting drugs work by either of two methods.Indirect acting drugs work by either of two methods.
 They can cause the release of the neurotransmitterThey can cause the release of the neurotransmitter
which then goes to the receptor site or they inhibit thewhich then goes to the receptor site or they inhibit the
enzyme cholinesterase.enzyme cholinesterase.
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Autonomic PharmacologyAutonomic Pharmacology
 Cholinergic PharmacologyCholinergic Pharmacology
 CardiovascularCardiovascular
• Direct effects include negative chronotropic andDirect effects include negative chronotropic and
inotropic actions.inotropic actions.
• Relaxation of smooth muscles causes a decrease inRelaxation of smooth muscles causes a decrease in
total peripheral resistance.total peripheral resistance.
• Indirect effects include increased heart rate andIndirect effects include increased heart rate and
cardiac output.cardiac output.
• The resulting effect depends upon the dose used.The resulting effect depends upon the dose used.
• Usually, the patient experiences bradycardia and aUsually, the patient experiences bradycardia and a
decrease in blood pressure and cardiac output.decrease in blood pressure and cardiac output.
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Autonomic PharmacologyAutonomic Pharmacology
 Cholinergic PharmacologyCholinergic Pharmacology
 GastrointestinalGastrointestinal
• These drugs excite the smooth muscle of theThese drugs excite the smooth muscle of the
gastrointestinal tract and cause an increase ingastrointestinal tract and cause an increase in
activity, motility, and secretion.activity, motility, and secretion.
 EyeEye
• These drugs cause miosis and cycloplegia.These drugs cause miosis and cycloplegia.
• They cause a decrease in intraocular pressure.They cause a decrease in intraocular pressure.
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Autonomic PharmacologyAutonomic Pharmacology
 Adverse ReactionsAdverse Reactions
 Adverse reactions are an extension of theAdverse reactions are an extension of the
drugs’ pharmacologic effects.drugs’ pharmacologic effects.
 They include:They include:
• SalivationSalivation
• LacrimationLacrimation
• UrinationUrination
• DefecationDefecation
• ParalysisParalysis
• OverdoseOverdose
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Cholinergic PharmacologyCholinergic Pharmacology
 ContraindicationsContraindications
 The contraindications and relative cautions areThe contraindications and relative cautions are
a result of the drug’s pharmacologic anda result of the drug’s pharmacologic and
adverse effects.adverse effects.
 They include:They include:
• Bronchial asthmaBronchial asthma
• HyperthyroidismHyperthyroidism
• Gastrointestinal or urinary tract obstructionGastrointestinal or urinary tract obstruction
• Myasthenia gravis treated with neostigmineMyasthenia gravis treated with neostigmine
• Peptic ulcer diseasePeptic ulcer disease
• Severe cardiac diseaseSevere cardiac disease
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Cholinergic DrugsCholinergic Drugs
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Anticholinergic DrugsAnticholinergic Drugs
 These drugs prevent the action ofThese drugs prevent the action of
acetylcholine at postganglionicacetylcholine at postganglionic
parasympathetic endings.parasympathetic endings.
 Acetylcholine is released but its receptor siteAcetylcholine is released but its receptor site
is completely blocked by anticholinergicis completely blocked by anticholinergic
drugs.drugs.
 These drugs only block muscarinic receptors.These drugs only block muscarinic receptors.
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Anticholinergic DrugsAnticholinergic Drugs
 PharmacologyPharmacology
 Central Nervous SystemCentral Nervous System
• Depending on the dose, these drugs can causeDepending on the dose, these drugs can cause
stimulation or depression.stimulation or depression.
 Exocrine GlandsExocrine Glands
• They reduce the flow and volume of secretions in theThey reduce the flow and volume of secretions in the
respiratory, gastrointestinal, and genitourinary tracts.respiratory, gastrointestinal, and genitourinary tracts.
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Anticholinergic DrugsAnticholinergic Drugs
 PharmacologyPharmacology
 Smooth MuscleSmooth Muscle
• Relax smooth muscles in the respiratory andRelax smooth muscles in the respiratory and
gastrointestinal tracts.gastrointestinal tracts.
• They delay gastric emptying and decreaseThey delay gastric emptying and decrease
esophageal and gastric emptying.esophageal and gastric emptying.
• These drugs also cause bronchial dilation.These drugs also cause bronchial dilation.
 EyeEye
• These drugs cause mydriasis and cycloplegia.These drugs cause mydriasis and cycloplegia.
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Anticholinergic DrugsAnticholinergic Drugs
 PharmacologyPharmacology
 CardiovascularCardiovascular
• With large doses, these drugs produce vagalWith large doses, these drugs produce vagal
blocking which results in tachycardia.blocking which results in tachycardia.
• Bradycardia can occur with low doses.Bradycardia can occur with low doses.
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Anticholinergic DrugsAnticholinergic Drugs
 Adverse ReactionsAdverse Reactions
 The adverse reactions are an extension of theThe adverse reactions are an extension of the
drugs’ pharmacologic effects.drugs’ pharmacologic effects.
 They include:They include:
• XerostomiaXerostomia
• ConstipationConstipation
• Urinary retentionUrinary retention
• Blurred visionBlurred vision
• HyperpyrexiaHyperpyrexia
• HallucinationsHallucinations
• PhotophobiaPhotophobia
• TachycardiaTachycardia
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Anticholinergic DrugsAnticholinergic Drugs
 ContraindicationsContraindications
 Contraindications are usually due to the drugs’Contraindications are usually due to the drugs’
pharmacologic and adverse effects.pharmacologic and adverse effects.
 They include:They include:
• GlaucomaGlaucoma
• Prostatic hypertrophyProstatic hypertrophy
• Intestinal or urinary obstruction or retentionIntestinal or urinary obstruction or retention
• Cardiovascular diseaseCardiovascular disease
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Anticholinergic DrugsAnticholinergic Drugs
 UsesUses
 Preoperative MedicationPreoperative Medication
• They inhibit salivary and bronchial secretions.They inhibit salivary and bronchial secretions.
• They block the vagal slowing of the heart that canThey block the vagal slowing of the heart that can
occur with general anesthesia.occur with general anesthesia.
 Gastrointestinal DisordersGastrointestinal Disorders
• They decrease gastrointestinal motility and can beThey decrease gastrointestinal motility and can be
used to treat ulcers, diarrhea, and hypermotility.used to treat ulcers, diarrhea, and hypermotility.
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Anticholinergic DrugsAnticholinergic Drugs
 UsesUses
 Ophthalmologic ExaminationsOphthalmologic Examinations
• Topical use can cause mydriasis which causes a fullTopical use can cause mydriasis which causes a full
visualization of the retina.visualization of the retina.
• Cycloplegia relaxes the lens so that properCycloplegia relaxes the lens so that proper
prescriptions for glasses can be determined.prescriptions for glasses can be determined.
 Parkinson DiseaseParkinson Disease
• They reduce the tremors and rigidity associated withThey reduce the tremors and rigidity associated with
Parkinson and drug-induced Parkinson disease.Parkinson and drug-induced Parkinson disease.
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Anticholinergic DrugsAnticholinergic Drugs
 UsesUses
 Motion SicknessMotion Sickness
• These drugs are used to treat or prevent motionThese drugs are used to treat or prevent motion
sickness because of their central nervous systemsickness because of their central nervous system
depressant action.depressant action.
 DentistryDentistry
• These drugs are used to create a dry, oral field.These drugs are used to create a dry, oral field.
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Adrenergic DrugsAdrenergic Drugs
 Adrenergic drugs can be classified as having directAdrenergic drugs can be classified as having direct
action, indirect action, or mixed action.action, indirect action, or mixed action.
 These drugs stimulateThese drugs stimulate αα andand ββ receptors throughoutreceptors throughout
the body.the body.
 Drugs with direct action (epinephrine, norepinephrine,Drugs with direct action (epinephrine, norepinephrine,
isoproterenol) produce their effect by directlyisoproterenol) produce their effect by directly
stimulating the receptor site.stimulating the receptor site.
 Drugs with indirect action (amphetamine) releaseDrugs with indirect action (amphetamine) release
endogenous norepinephrine which then stimulatesendogenous norepinephrine which then stimulates
the receptor.the receptor.
 Drugs with mixed action (ephedrine) either directlyDrugs with mixed action (ephedrine) either directly
stimulate the receptor or release endogenousstimulate the receptor or release endogenous
norepinephrine.norepinephrine.
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Adrenergic DrugsAdrenergic Drugs
 PharmacologyPharmacology
 Central Nervous System (CNS)Central Nervous System (CNS)
• These drugs produce CNS excitation or alertness.These drugs produce CNS excitation or alertness.
• Higher doses produce anxiety, apprehension,Higher doses produce anxiety, apprehension,
restlessness, and tremors.restlessness, and tremors.
 Cardiovascular SystemCardiovascular System
• These drugs increase the force and rate ofThese drugs increase the force and rate of
contraction of the heart.contraction of the heart.
• Blood pressure is also increased.Blood pressure is also increased.
• Total peripheral resistance is also increased.Total peripheral resistance is also increased.
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Adrenergic DrugsAdrenergic Drugs
 PharmacologyPharmacology
 EyeEye
• These drugs lower intraocular pressure and can causeThese drugs lower intraocular pressure and can cause
mydriasis.mydriasis.
 Respiratory SystemRespiratory System
• These drugs cause a relaxation of bronchiole smoothThese drugs cause a relaxation of bronchiole smooth
muscles.muscles.
 Metabolic EffectsMetabolic Effects
• Increased glycogenolysis fromIncreased glycogenolysis from ββ-receptor stimulation-receptor stimulation
causes hyperglycemia.causes hyperglycemia.
 Salivary GlandsSalivary Glands
• These drugs produce vasoconstriction of the salivaryThese drugs produce vasoconstriction of the salivary
glands which leads to decreased salivary flow whichglands which leads to decreased salivary flow which
results in xerostomia.results in xerostomia.
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Adrenergic DrugsAdrenergic Drugs
 Adverse ReactionsAdverse Reactions
 The adverse reactions associated with theseThe adverse reactions associated with these
drugs are an extension of the drugs’drugs are an extension of the drugs’
pharmacologic effects.pharmacologic effects.
 They include:They include:
• AnxietyAnxiety
• TremorsTremors
• TachycardiaTachycardia
• Increased blood pressureIncreased blood pressure
• ArrhythmiasArrhythmias
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Adrenergic DrugsAdrenergic Drugs
 UsesUses
 VasoconstrictionVasoconstriction
• These drugs are used in dentistry because of theirThese drugs are used in dentistry because of their
vasoconstrictive actions on blood vessels. They arevasoconstrictive actions on blood vessels. They are
added to local anesthetics because they prolong theadded to local anesthetics because they prolong the
action of the local anesthetic, reduce the risk foraction of the local anesthetic, reduce the risk for
systemic toxicity, and help to create a dry field.systemic toxicity, and help to create a dry field.
 Cardiac EffectsCardiac Effects
• These drugs are used to raise blood pressure and toThese drugs are used to raise blood pressure and to
treat cardiac arrest.treat cardiac arrest.
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Adrenergic DrugsAdrenergic Drugs
 UsesUses
 BronchodilationBronchodilation
• These drugs are used to treat asthma, emphysema,These drugs are used to treat asthma, emphysema,
and allergic reaction.and allergic reaction.
 Central Nervous System StimulationCentral Nervous System Stimulation
• These medications are used for the treatment ofThese medications are used for the treatment of
attention deficit hyperactivity disorder, narcolepsy,attention deficit hyperactivity disorder, narcolepsy,
and as diet aids.and as diet aids.
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Adrenergic Blocking DrugsAdrenergic Blocking Drugs
 These drugs competitively inhibitThese drugs competitively inhibit αα andand ββ
receptor sites.receptor sites.
 One group of drugs is specific forOne group of drugs is specific for αα
receptors.receptors.
 One group of drugs is specific for bothOne group of drugs is specific for both ββ11 andand
ββ22 receptors.receptors.
 One group is specific forOne group is specific for ββ22 receptors.receptors.
 One group is specific for bothOne group is specific for both αα andand ββ
receptors.receptors.
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Antiadrenergic DrugsAntiadrenergic Drugs
 PharmacologyPharmacology
 These drugs reduce sympathetic tone in theThese drugs reduce sympathetic tone in the
blood vessels and decrease total peripheralblood vessels and decrease total peripheral
resistance.resistance.
 This results in a reduction in blood pressure.This results in a reduction in blood pressure.
 UsesUses
 These drugs are used to treat hypertension,These drugs are used to treat hypertension,
peripheral vascular disease (i.e., Raynaudperipheral vascular disease (i.e., Raynaud
syndrome) and benign prostatic hypertrophy.syndrome) and benign prostatic hypertrophy.
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