12.2 Cholinergic and Anticholinergic

Question 1

Cholinergic Receptors

Answer 1

• Parasympathetic receptors activated by binding to acetylcholine (neurotransmitter)

Question 2

Acetylcholine Functions

Answer 2

• Neurotransmitter
  Brain - Memory storage and retrieval
  GI Tract - Promotes normal secretory/motor activity
  Urinary Tract - Muscle contraction/relaxation to facilitate urination

Question 3

Cholinergic Drugs

Answer 3

• Mimic or block actions of acetylcholine

- Can also prevent breakdown of acetylcholine (cholinesterase inhibitors)

Question 4

Cholinergic Receptor Types

Answer 4

Nicotinic - Responsive agonist to nicotine

Muscarinic - Responsive agonist to muscarine

Question 5

Nicotinic Receptors

Answer 5

• Nicotine selectively binds to nicotinic receptors
• Antagonist block transmission at the synapse of autonomic ganglia, skeletal neuromuscular junction, and CNS nicotinic synapses
• They are also called (Ganglionic Blockers)
• Blocking the receptors produce anticholinergic effects.
• Triggers rapid neural and neuromuscular transmission

Question 6

Muscarinic Receptors

Answer 6

• Slows heart rate, contraction of smooth muscle, increase secretion from exocrine glandular tissue (salivary, gastric acid, airway mucosal glands).
• Antagonist (anticholinergics) produce mydriasis and bronchodilation, increase heart rate, inhibit secretions.

Question 7

Effects of Direct Acting Cholinergics

Answer 7

• Decreased HR, Vasodilation, BP
• Increased GI, Urinary Bladder, Bronchial Smooth Muscle tone and contractility
• Increased Salivary, GI, Respiratory secretions
• GI and Urinary Sphincter relaxation
• Pupil constriction and ciliary contraction (accommodates near sightedness)

Question 8

Bethanechol (Urecholine) - Urinary Retention

Answer 8

• Treats urinary retention
• Stimulates muscarinic receptors (no affect on nicotinic)
• Increases tone of detrusor muscle for bladder and gastric tone motility to urinate and defecate
• Poorly absorbed in GI tract (30-90 min)
• SubQ Onset (5-15 min)
  Adverse Effects - Flushing, Watery Eyes, Increased Saliva/Urination, Dizziness, Headache, Lightheadedness
  Contraindications - Obstructions, Inflammatory Bowel Disease, Peritonitis, Recent Bladder/GI Surgery
  Antidote - Atropine Sulfate

Question 9

Myasthenia Gravis

Answer 9

• Cholinesterase Inhibitor (Neostigmine, physostigmine)
• (ChEI) Prevent breakdown of acetylcholine. Increases amount of acetylcholine in synaptic cleft.
• Improves skeletal muscle and strength.

Question 10

Neostigmine (Prostigmin) - Cholinesterase Inhibitor

Answer 10

• Treatment of myasthenia gravis
  (Autoimmune disorder, antibodies destroy communication between nerves and muscle)
• Reverses affects of muscle relaxants such as tubocurarine and pancuronium.
• Does not cross BBB

Question 11

Neostigmine

Answer 11

• Poorly absorbed in GI Tract from Oral Administration
  Adverse Effects
• Excessive salivation, increased gastric secretions, increased GI tone and motility, urinary urgency, bradycardia, sweating, polarizing neuromuscular blockage and respiratory depression
  Contraindications
• Hypersensitivity and peritonitis or obstruction to GI tract and urinary tract
• IV, IM, SC
  ANTIDOTE - Atropine

Question 12

Myasthenia Gravis

Answer 12

• Autoimmune disorder that affects neuromuscular junction and reduces acetylcholine receptors.
• Muscle weakness, hypoventilation, inability to cough effectively.
• Take with food or milk to reduce gastric distress/ulceration.

Question 13

Edrophonium (Tensilon)

Answer 13

• Used to diagnose Myasthenia Gravis not treat
• Effects only last an hour
• 2-4 mg IV
• Can cause bronchospasm, excess bronchial secretions, GI problems.

Question 14

Alzheimer’s Disease

Answer 14

• Cholinesterase Inhibitor (Donepezil, tacrine)
• Enhances transmissions by central cholinergic neurons that haven’t been destroyed
• Slows disease progression
• For patients with mild to moderate AD
• Improvements are modest and short term

Question 15

Glaucoma

Answer 15

Cholinergic (Miotic)

• Reduce eye pressure by increasing drainage of intraocular fluid.
• Can be used alone or with other glaucoma medication

Question 16

Anticholinergic Effects

Answer 16

• Antidote for Cholinergic Effects

Question 17

Anticholinergics

Answer 17

• Block acetylcholine from reaching receptors.
• Decrease respiratory secretions, sweat and saliva
• Dilate pupils
• Photophobia
• Increased intraocular pressure
• CNS stimulation followed by depression
• Increased HR
• Bronchodilation
• Relaxation of bladder

Question 18

Anticholinergic Adverse Effects

Answer 18

• Cant pee, see, spit, poop
• Hot as hare (increased body temperature
• Blind as bat (Mydriasis dilated pupils)
• Dry as bone (Dry mouth, eyes, decreased sweat)
• Red as a beet (flushed face)
• Mad as a hatter (delirium)

Question 19

Therapeutic Effects of Anticholinergics

Answer 19

• Antimuscarinic Agents
  Atropine - Increase HR (therapy for bradycardia/heart block)
  Benztropine - Manage involuntary movement for Parkinson’s disease
  Dicyclomine/Hyoscyamine - Antispasmodic effects in GI or Genitourinary Disorders
  Atropine - Pre-op or pre-bronchoscopy to reduce secretions
  Atropine - Dilate pupils

Question 20

Atropine (Atropen) - Antimuscarinic

Answer 20

• Inhibits parasympathetic nervous system
• Treat bradycardia, decrease salivary production, ophthalmic solution can mydriatic (dilate) pupils.
• Bronchial relaxation, decrease urinary bladder tone, decrease motility of GI tract, CNS excitation, pupil dilation.
• IV lasts 1/2 - 1 hour
• Adverse effects dry mouth, blurred vision, lack of sweating, tachycardia, glaucoma, pyloric obstruction, urinary retention, bronchial mucus plugs.
• Careful using in patients with glaucoma, pyloric stenosis, prostatic hypertrophy.
• Antidote is physostigmine or pilocarpine

Question 21

Muscarinic Antagonist

Answer 21

• Atropine given to patients who are poisoned
• Antidote to cholinergic agents
• Reverses muscarinic effects such as heart, smooth muscle, and glands.
• Cannot reverse nicotinic effects of skeletal muscle weakness or paralysis.

Question 22

Nicotinic Antagonist

Answer 22

• Mecamylamine used to treat moderate to severe hypertension but now used as smoking cessation.
• Poison dart to frogs

Question 23

Organophosphate Antagonist

Answer 23

• Pralidoxime (2-PAM)

- Cholinesterase reactivator used to treat organophosphate poisoning.

Question 24

Cholinergic Toxicity

Answer 24

• Monitor decreased heart rate
• Vasodilation
• BP Changes
• Increased GI, Urinary, and bronchial tone and contractility
• Increased salivary, GI, Respiratory secretions
• GI/Urinary sphincter relaxation
• Pupillary constriction

Question 25

Emergency treatment for Cholinergic Toxicity

Answer 25

• Endotracheal intubation (airway)
• Give copious amounts of water (decontamination)
• Activated charcoal/lavage
• Antidotes
  Atropine to Muscarinic
  Pralidoxime (2-PAM) for Nicotinic