Drugs%20Affecting%20the%20Autonomic%20Nervous%20System

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Drugs Affecting the Autonomic Nervous System

• Cholinergic Drugs

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Cholinergic Drugs

• Describe the cholinergic drug effects on major
  body systems.
• Discuss the nursing process related to the care
  of patients receiving cholinergic drugs for
  select problems.

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Cholinergic Drugs

• Drugs that stimulate theparasympathetic nervous
  system (PSNS)
• opposing system to the SNS
• Known as cholinergic agonists or
  parasympathomimetics
• Mimic the effects of the PSNS neurotransmitter
  acetylcholine (Ach)
• Two types of Receptors
• determined by Location Action once stimulated
• Muscarinic receptors recommended doses with
  desired effect
• Nicotinic receptors higher doses with
  undesirable effects

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Cholinergic DrugsMechanism of Action

• Direct-acting cholinergic agonists
• Bind to cholinergic receptors, activating them
• Indirect-acting cholinergic agonists
• Inhibit the enzyme acetylcholinesterase -
  prventing, which breaks down ACh - more ACh is
  available at the receptors
• Reversible - Bind to cholinesterase for a period
  of minutes to hours
• Irreversible - Bind to cholinesterase and form a
  permanent covalent bond
• The body must make new cholinesterase to break
  these bonds

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Cholinergic Drugsrest and digest system

• SLUDGE
• Salivation
• Lacrimation
• Urinary incontinence
• Diarrhea
• Gastrointestinal cramps
• Emesis

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Cholinergic DrugsDrug Effects

• Stimulate intestine and bladder
• Increased gastric secretions
• Increased gastrointestinal motility
• Increased urinary frequency
• Stimulate pupils
• Constriction (miosis)
• Reduced intraocular pressure
• Increased salivation and sweating
• Cardiovascular effects
• Decreased heart rate
• Vasodilation
• Respiratory effects
• Bronchial constriction, narrowed airways

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Cholinergic DrugsDrugs

• Bethanechol (Urecholine) urinary retention
• Cevimeline (Evoxac) Xerostomia
• Memantine (Namenda) Alzheimers dementia
• Physostigmine (Antilirium) reversal of
  anticholinergic drugs effects
• Pyridostigmine (Mestinon) Myasthenia gravis

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Cholinergic DrugsIndications

• Direct-acting drugs
• Reduce intraocular pressure
• Topical useful for glaucoma and intraocular
  surgery
• pilocarpine

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Cholinergic DrugsIndications

• Direct-acting drugbethanechol (Urecholine)
• Increases tone and motility of bladder and GI
  tract
• Relaxes sphincters in bladder and GI tract,
  allowing them to empty
• Used to reverse postsurgical atony of the bladder
  and GI tract
• Oral dose or SC injection

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Cholinergic DrugsIndications

• Indirect-acting drugs
• Cause skeletal muscle contractions
• Used for diagnosis and treatment of myasthenia
  gravis
• Pyridostigmine (Mestinon) Myasthenia gravis
• Used to reverse neuromuscular blocking
  drugs/anesthesia
• Used to reverse anticholinergic poisoning
  (antidote)
• Examples physostigmine (Antilirium)

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Cholinergic DrugsIndications

• Indirect-acting drugscevimeline (Evoxac)
• Used to treat xerostomia (dry mouth) resulting
  from Sjögrens syndrome

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Cholinergic DrugsAdverse Effects

• Adverse effects are a result of overstimulation
  of the PSNS
• Cardiovascular
• Bradycardia, hypotension, conduction
  abnormalities (AV block and cardiac arrest)
• CNS
• Headache, dizziness, convulsions
• Gastrointestinal
• Abdominal cramps, increased secretions, nausea,
  vomiting
• Respiratory
• Increased bronchial secretions, bronchospasm
• Other
• Lacrimation, sweating, salivation, loss of
  binocular accommodation, miosis

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Cholinergic DrugsInteractions

• Anticholinergics, antihistamines,
  sympathomimetics
• Antagonize cholinergic drugs, resulting in
  decreased responses
• Other cholinergic drugs
• Additive effects

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Cholinergic DrugsNursing Implications

• Assess for allergies, presence of GI or GU
  obstructions, asthma, peptic ulcer disease, or
  coronary artery disease
• Perform baseline assessment of vital signs and
  systems overview
• Medications should be taken as ordered and not
  abruptly stopped
• The doses should be spread evenly apart to
  optimize the effects of the medication
• Overdosing can cause life-threatening problems.
  Only physicians should adjust the dosages

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Cholinergic DrugsNursing Implications

• Encourage patients with myasthenia gravis to take
  medication 30 minutes before eating to help
  improve chewing and swallowing
• When cholinergic drugs are prescribed for
  Alzheimers disease, be honest with caregivers
  and patients that the drugs are for management of
  symptoms, not a cure
• Therapeutic effects of anti-Alzheimers drugs may
  not occur for up to 6 weeks

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Cholinergic DrugsNursing Implications

• Monitor for therapeutic effects
• Alleviated signs and symptoms of myasthenia
  gravis
• In postoperative patients with decreased GI
  peristalsis, look for
• Increased bowel sounds
• Passage of flatus
• Occurrence of bowel movements
• In patients with urinary retention/hypotonic
  bladder, urination should occur within 60 minutes
  of bethanechol administration
• ALSO monitor for adverse effects