Agents Affecting the Autonomic Nervous System

1
Chapter 33

• Agents Affecting the Autonomic Nervous System

2
Autonomic Nervous System

• Includes two neurotransmitters
• Norepinephrine and acetylcholine
• Two branches
• Sympathetic
• Adrenergic
• Fight or flight
• Parasympathetic
• Cholinergic
• Rest and digest

3
Sympathetic Nervous System (SNS)

• Stimulates vital organs
• Suppresses nonvital body functions
• Signs of stimulation of the SNS
• Pupil dilation
• Bronchiole dilation
• Increased rate and force of contraction
• Blood vessel dilation in muscle tissue
• Increased breakdown of glycogen to glucose

4
Sympathetic nervous system receptors

• Alpha
• Found in smooth muscle tissue of peripheral blood
  vessels and in the sphincters of the
  gastrointestinal and genitourinary system
  respond to norepinephrine
• Beta
• Found mainly in the heart, lungs, and brain,
  respond to epinephrine

5
Alpha Receptors

• Alpha 1
• - Primarily in the smooth muscle tissue of
  peripheral blood vessels and the sphincters of
  the GI and genitourinary (GU) tracts
• - When stimulated, smooth muscle contracts
• Anorexiants dextroamphetamine (Dexedrine),
  methamphetamine (Desoxyn)

6
Alpha Receptors

• Alpha 2
• - Functions as controllers of
  neurotransmitter release
• - When stimulated, release of
  neurotransmitters from the presynaptic neurons
  are decreased

7
Beta Receptors

• Beta 1
• - Primarily in the heart and fatty tissue
• - When stimulated, rapid heart rate, more
  forceful heart contraction, and the breakdown of
  stored fat to fatty acids occurs

8
Beta Receptors

• Beta 2
• Primarily in bronchial smooth muscle and the
  walls of blood vessels
• produces bronchodilation when stimulated by
  adrenergic drugs
• albuterol, epinephrine, terbutaline
• When stimulated, bronchial muscles relax and
  diameter of airways increases

9
Adrenergic Receptors

• produces increased contractility, increased heart
  rate, and AV and sinoatrial (SA) node conduction
  when stimulated by adrenergic drugs
• dobutamine, dopamine, and norepinephrine

10
Parasympathetic Nervous System (PNS)

• One neurotransmitter
• Acetylcholine
• Conserves energy
• Promotes nutrient use

11
Drugs Affecting the ANS

• Sympathomimetic adrenergic drugs
• Stimulate the system fight-or-flight
• Sympatholytic adrenergic blocking drugs
• Block alpha and beta receptors

12
Drugs Affecting the ANS

• Parasympathomimetic cholinergic drugs
• Mimic the PNS
• Parasympatholytic anticholinergic drugs
• Block acetylcholine receptors

13
Sympathomimetics (Adrenergics)

• Mimic the action of the sympathetic nervous
  system
• Neurotransmitters norepinephrine, epinephrine,
  and dopamine (catecholamines)

14
Sympathomimetics (Adrenergics)

• Catecholamine receptor sites are where
  adrenergics bind and produce their response at
  locations throughout the body

15
Geriatric Considerations for Adrenergics

• More sensitive to the effects of adrenergics
• Must be monitored for excessive cardiac and CNS
  stimulation
• Signs and symptoms to watch for include
• - chest pain
• - palpitations
• - blurred vision
• - headache
• - seizures
• - hallucinations
• Notify provider immediately for these symptoms

16
Sympatholytics (Adrenergic Blockers)

• Block or inhibit the responses of adrenergic
  neurotransmitters at the alpha and beta receptor
  sites

17
Alpha-adrenergic Blockers

• Inhibits the response at the alpha receptors
• Causes vasodilation and decreases blood pressure
• Used to treat migraine headaches, hypertension,
  and peripheral vascular diseases (promotes blood
  flow to vasoconstricted areas)

18
Alpha-adrenergic Blockers

• Adverse effects can include hypotension,
  dizziness, and ejaculation suppression
• Commonly used alpha blockers are ergotamine
  tartrate (for migraines), and tolamine and
  prazosin (for hypertension)

19
Beta-adrenergic Blockers

• Blocks the beta receptor sites in the heart
• Decreases pulse rate and controls angina pectoris
• Decreases firing rate in the SA node and
  conduction velocity in the AV node and therefore,
  treats dysrhythmias

20
Beta-adrenergic Blockers

• They also decrease blood pressure and cause
  bronchoconstriction
• Use with caution in patients with asthma and COPD
• Some common drugs are propranolol, metoprolol,
  and atenolol

21
Adrenergic Blockers

• Treat
• Hypertension
• Migraine headache
• Side effects/adverse effects
• Hypotension
• Dizziness

22
Adrenergic Blockers Geriatric Considerations

• Increase sensitivity to adrenergic drugs
• Monitor for
• Chest pain
• Palpitations
• Blurred vision
• Headache
• Seizures
• Hallucinations

23
Cholinergics

• Stimulate the PNS
• Treat
• Conditions with poor muscular contraction
• Neurogenic bladder
• Glaucoma
• Cardiac arrhythmias

24
Cholinergics Geriatric Considerations

• Increase sensitivity to cholinergic drugs
• Monitor for
• Diarrhea
• Increased bronchoconstriction
• Increased bronchial secretions
• Increased lacrimation
• Blurred vision

25
Anticholinergics

• Action
• Decrease gastrointestinal and respiratory
  secretions
• Dilate bronchioles
• Dilate pupils
• Treat
• Nausea
• Urinary incontinence
• Overactive bladder

26
Anticholinergics Geriatric Considerations

• Increase sensitivity to anticholinergic drugs
• Hyperthermia
• Urinary retention
• Decreased appetite