Lecture 11/12 - Cholinergic Agonists Flashcards Preview

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Flashcards in Lecture 11/12 - Cholinergic Agonists Deck (79):
1

What are the direct acting cholinergic agonists? (six)

ACh
Muscarine
Nicotine
Carbachol
Bethanechol
Pilocarpine

2

What are the cholinesterase inhibitors? (six)

Edrophonium
Neostigmine
Pyridostigmine
Physostigmine
Organophosphates
Pralidoxime

3

What abnormality inhibits ACh release?

Botulism

4

What can prolong the effects of ACh?

AChE inhibitors

5

What does ACh stimulate?

M + N

6

Where are muscarinic receptors located?

PNS effector organs

7

What is M1+3 linked to?

Gq

8

What is M2 linked to?

Gi

9

Where are muscarinic receptors where the PNS is not?

Sweat glands

10

What do nicotinic receptors respond to?

ACh + Nicotine

11

What is a special characteristic of nicotinic recptors?

Rapid desensitization

12

Where are nicotinic receptors found?

Brain
Adrenal medulla
Autonomic ganglia
NMJ

13

Why can drugs select between NMJ and autonomic nicotinic receptors?

Both have different structures

14

What is direct action?

Agonist binds and stimulates receptor

15

What is indirect action?

Molecule binds to enzyme or other part of pathway that leads to a different effect of NT

16

What will happen with ACh injection/

Slowing of HR - M2
Drop in BP - M3

17

Why can't you give ACh orally?

Charged, not absorbed

18

What does bethanechol stimulate?

M receptors only

19

What effects predominate with bethanechol?

Bladder + GI

20

Does bethanechol enter the brain? Why?

No, charged

21

What does pilocarpine stimulate?

M receptors only

22

What are the distribution characteristics of pilocarpine?

Not charged, so taken orally
Gets into CNS

23

What is pilocarpine used for in the eye?

Decrease intraocular pressure (M3)

24

What is really sensitive to pilocarpine that leads to side effects? what are the effects?

Sweat + Salivary glands
Drooling

25

What does muscarinic stimulation do to the heart?

Vagal stimulation = Bradycardia (M2)
Atrial-muscarinic receptors
Conduction slowed through AV node
Pre-synaptic decrease NE = Decrease HR (M2)

26

What does muscarinic stimulation do to the blood vessels?

NO PNS, but M3 is present on endothelium
ACh given IV will cause vasodilation

27

How does ACh given IV cause vasodilation?

NO

28

What happens with release of NO from endothelial cells?

cGMP production + Vasodilation

29

What is the PNS tone like in the GI tract?

High, responsible for digestion

30

What are the effects of muscarine on the GI tract?

Motility + Peristalsis increase
Tone increases
Salivary + Gastric secretions increase
Sphincters relax

31

How is carbachol used with horses?

Treatment of colic or impactions

32

What do you have to watch out for when using carbachol in horses?

If obstruction is present can lead to intestinal rupture

33

What is carbachol used for in cattle?

Rumen atony and impaction

34

What does normal PNS activity do to the bladder?

Enhances overall activity

35

What do muscarinic drugs do to the bladder?

Bladder tone + peristalsis increase
Void pressure increase
Bladder capacity decrease
Detrusor contracts
Trigone and sphincter relax

36

What is the basic end result of muscarinic stimulation of the bladder?

Increased urination

37

What drug is used for bladder effects?

Bethanechol

38

What is betahanechol used for?

Urinary atony in cats following urolithiasis

39

What do you have to watch out for when using betanechol in cats?

That the urethra is patent, so they can control urine output

40

What are the muscarinic effects in the eye?

Circular muscle contraction = Pupil smaller
Increased AH drainage = Decreased pressure
Ciliary muscle contracts = Near vision

41

How is pilocarpine used in the eye?

KCS + Glaucoma

42

What are the side effects of pilocarpine in the eye?

Blurred vision + Brow ache

43

What are the muscarinic side effects?

Nausea + V/D + Colic
Bladder tightness = Increased urination
Salivation
Bronchoconstriction + increased mucus
Blurred vision
Constricted pupils

44

What happens with muscarine toxicity?

Same as side effects just worse
Hypotension + Shock + Bradycardia

45

What is muscarine toxicity treated with?

Atropine + Albuterol

46

What are the three main places for nicotinic receptors?

Autonomic ganglia
Skeletal muscle
Brain

47

What type of channel is nicotinic receptors?

Ligand gated Na+ channel

48

What movement of ions occurs with an activated nicotinic receptor?

Na/Ca = in
K = out

49

What, in the most general sense, does N activate?

SNS + PNS

50

What are the SNS effects with nicotinic stimulation?

Hypertension
Tachycardia w/ vagal bradycardia

51

What are the PNS effects with nicotinic stimulation?

Nausea + Vomiting + Diarrhea + Urination

52

What happens with desensitization of the NMJ?

Initial muscle twitch/contraction + depolarization blockcade

53

What is seen with nicotine toxicity?

Vomiting
Convulsion + coma + respiratory arrest
Skeletal muscle depolarization
Hypertension + Cardiac arrythmia

54

What three things are done to treat nicotine toxicity?

Atropine + Anticonvulsants + Assist respiration

55

What are the four major drugs that affect AChE? (not toxins)

Neostigmine
Physostigmine
Pryidostigmine
Edrophonium

56

What are the five examples of Organophostphates?

DFP + Eschothiophate + Soman + Sarin + Malathion

57

What are the distribution characteristics of neostigmine?

Charged, cant be taken orally + no CNS N
Acts mostly on skeletal muscle

58

How does pyrdiostigmine compare to neostigmine?

Longer acting

59

What are the general characteristics of Physostigmine?

Enters CNS
U-shaped response curve

60

What is Physostigmine used for?

Atropine toxicity

61

What is the duration of action for Edrophonium?

Very short = 5 to 10 min

62

What is edrophonium used for?

Diagnosis of myasthenia-like syndrome

63

What is used to treat myasthenia-like syndrome?

Neostigmine

64

What is the problem with organophosphates?

Long-lasting effect
Due to aging, becomes irreversible

65

What can stop oragnophosphate aging?

2-PAM, if given 3 to 4 hours post-exposure

66

How does aging occur?

Phosphorus-Oxygen bonds breaks
Bond to AChE irreversible

67

Why does 2-PAM stop the "aging" process"?

Strong nucleophile
Attracts organophosphate away from AChE

68

What is important to remember when using 2-PAM?

If organophosphate not present it can inhibit AChE itseld

69

What are the CNS effects of AChE inhibition?

Convulsions + respiratory arrest

70

What are the effects of AChE inhibition on the eye?

Miosis
Near vision

71

What are the effects of AChE inhibition on GI/bladder?

V/D + Abdominal cramps + Urination

72

What are the effects of AChE inhibition on the respiratory system?

Salivation + Secretion + Bronchoconstriction

73

What are the cardiovascular effects of AChE inhibition?

PNS dominates
Prolonged ACh = M2 stimulation
Bradycardia + Decrease contraction + Decrease CO

74

What happens with low concentrations of AChE inhibitors at the NMJ?

Skeletal muscle strength increases

75

What happens with high concentrations of AChE inhibitors at the NMJ?

Twitches + Fasiculation
Blockade
Paralysis

76

What is myasthenia gravis?

Autoimmune disease
Ab's to nicotinic receptors
Not enough ACh to stimulate
Weakness and fatigue with excercise

77

What is physostigmine used for?

Eye = miosis + decrease pressure
Synechia = alternate with atropine
Rumen atony = in cattle

78

What are the side effects of AChE inhibitor toxicity?

Salivation + Lacrimation + Urination + Defecation + Gastric distress + Emesis

79

What is the withdrawal time in meat and milk for 2-PAM (pralidoxime)?

28 days for meat
6 days for milk