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AU15 - Pharmacology Test 2 > Cholinergic Drugs > Flashcards

Cholinergic Drugs Flashcards

1
Q

What are the two types of Cholinergic Receptors?

A

Nicotinic Receptors

Muscarinic Receptors

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2
Q

What is the structure of a nicotinic receptor?

A

Made up of 5 subunits and binds 2 molecules of agonist

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3
Q

What is the difference between Skeletal muscle nAcChR molecular biology in skeletal muscle and the CNS?

A

Skeletal is fairly simple

CNS is complicated

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4
Q

Why do fetal and and adult skeletal muscles have somewhat different properties?

A

They have 1 subunit on their nicotonic receptors that is different

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5
Q

Why are CNS AcChR so complicated?

A

They have many different subunits

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6
Q

What type of receptors are muscarine receptors?

A

G-protein coupled receptors

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7
Q

What are the different types of muscarine receptors?

A

M1, M2, M3, M4, M5
The odd numbers do one thing
The even numbers do other things

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8
Q

What is the significance of M1, M3, and M5?

A

They are linked to Gaq
They activate DAG and IP3 signaling
They increase Ca and ultimately create contractility

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9
Q

What is the significance of M2 and M4?

A

They are linked to Gai

They inhibit adenylate cyclase

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10
Q

What is the inderirect acting mechanism of Cholinergic agonist

A

Cholinesterase inhibition

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11
Q

Acetylcholine

A

A non-specific cholinergic agonist

Binds to the target and is hydrolyzed once its work is done

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12
Q

Carbachol

A

Non-specific cholinergic agonist (but mainly binds to nicotinic receptors)
Isn’t hydrolyzed as readily as Acetylcholine

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13
Q

Muscarine

A

Specific cholinergic agonist for muscarinic recptors

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14
Q

Nicotine

A

Specific cholinergic agonist for nicotinic receptrs

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15
Q

T/F - different agonists have different selectivity

A

True

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16
Q

Hydrolysis by cholinesterase has a profound effect on what?

A

They duration of action of cholinergic agonist

The higher the rate of hydrolysis, the shorter the duration of action

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17
Q

How fast does Acetylcholine hydrolyze?

A

Very rapidly, and has the shortest duration of action

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18
Q

How fast does Methacholine hydrolyze?

A

Slower, so it has a longer duration of action

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19
Q

What are the hydrolysis rates on Carbachol, bethanechol, cevimeline, and alkaloids?

A

They are not hydrolyzed, so they have the longest duration of action

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20
Q

What is the selectivity of methacholine, bethanochol, muscarine, cavimeline, and pilocarpine?

A

They are all muscarinic selective

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21
Q

Are nicotinic agonist or muscarinic agonist more clinically relevant?

A

Muscarinic

nicotinic is still important for overall physiology

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22
Q

What is the molecular mechanism of Nicotinic receptors?

A

1) Activation of nicotine AcCh receptors depolarize the postsynaptic membrane
2) Local depolarization leads to an AP
3) Post-synaptic depolarization leads to the release of Ca from the SR
4) Release of Ca from the SR leads to muscle contraction

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23
Q

What is the molecular mechanism of M1, M3, M5?

A

Activate phospholipase C and promotes Ca release

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24
Q

What is the molecular mechanism of M2 and M4?

A

Inhibit adenylate cyclase

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25
Q

What pharmacological effects do muscarinic receptors have on the eye?

A

M3 receptors are on the sphincter muscle.
-Activation mediates pupil contraction
M3 receptors on the ciliary muscles also mediate contraction
-This increases drainage by the trabecular network and reduces ocular pressure

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26
Q

What pharmacological effects do muscarinic receptors have on the heart?

A

Cardiac muscles contain M2 receptors

Activation reduces cardiac output

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27
Q

What pharmacological effects do muscarinic receptors have on vasodilation?

A

Vascular endothelial cell express M3 receptors

  • Activation increases Ca in endothelial cells
  • Ca/Calmodulin activates NOS to produce NO
  • NO travels to the smooth muscle, enhances cGMP production, leading to muscle relaxation and vasodilation
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28
Q

What pharmacological effects do muscarinic receptors have on bronchoconstriction?

A

M3 muscarinic receptors on the bronchial muscle mediate contraction

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29
Q

What pharmacological effects do muscarinic receptors have on GI tracts?

A

Mostly contractile

However, M2 receptors relax the sphincter muscles

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30
Q

What pharmacological effects do muscarinic receptors have on secretory glands?

A

M3 receptors lead to the release of Ca

This release stimulates the release of glandular contents from the secretory glands

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31
Q

What pharmacological effects do muscarinic receptors have on the Urinary tract?

A

M3 muscarinic receptors mediate detrusor muscle contraction - this aids in the voiding of bladder

32
Q

What pharmacological effect do muscarinic receptors have on the CNS?

A

There are CNS effects, but they are complex and not part of common theraputic strategies

33
Q

Which are absorbed better, tertiary or quaternary amines?

A

Tertiary, because they are uncharged. Quaternary amines are charged

34
Q

Why are the effects of AcCh effects so quick?

A

Because AcCh is rapidly hydrolyzed

35
Q

What patients have an increased risk of adverse effects of muscarinic agonists?

A

Patients with asthma
Patients with cardiovascular disease
Patients with ulcers

36
Q

What are some adverse effects of activated muscarinic receptors?

A 
SLUD responses (Salivation, Lacrimation, Urination, Defication)
Hypertensive response
37
Q

Acetylcholinesterase

A

An enzyme that hydrolyzes Ach into Acetic acid and choline

38
Q

MOA

A

Acetylcholine drugs that work by inhibiting acetylcholinesterase…
thereby inhibiting hydrolysis of Ach and increasing the concentration in the synapse, which promotes Ach action
Since they promote Ach activity w/o binding to a receptor, they are an indirect cholinergic agonist

39
Q

T/F - Some “reversible” anticholinesterases are rapidly hydrolyzed by cholinesterase

A

False - they are slowly hydrolyzed by cholinesterase

40
Q

T/F - Anticholinesterases act in a unidirectional manner

A

False - Some anticholinesterases act in a rapidly reversible manner

41
Q

What are Malathian and Sarin

A

Organophosphate anticholinesterase that act in a completely irreversible manner
They covalently react with the enzyme and are not hydrolyzed unless treated with an antidote
These are used as poisons

42
Q

Anticholinesterase drugs produce effects that are similar to what?

A

Cholinergic agonists

because they increase the concentration of ACh at the effector site

43
Q

Greater cholinergic stimulation leads to what?

A

The greater the effect

44
Q

Why do anticholinesterases not produce muscarinic receptor mediated vasodilation? How can we produce vasodilatory effects?

A

There is no parasympathetic innervation of vascular endothelium
Can produce vasodilatory effects through autonomic ganglia

45
Q

What effects can Physostigmine produce?

A

Vasodilatory effects in the CNS

46
Q

Where is Physostigmine absorbed?

A

After oral subcutaneous and topical administration

47
Q

What are some theraputic uses for cholinergic agonists and anticholinesterases?

A 
Glaucoma
Xerostomia
Reversal of neuromuscular block
Myasthenia Gravis
Cross the BBB to improve cognitive function of Alzheiemer's patients
48
Q

What is glaucoma?

A

Atrophy of the optic nerve and loss of vision due to elevation in intraocular pressure

49
Q

How can cholinergic agonists and anticholinesterases treat glaucoma?

A

Stimulating musculature of the iris and ciliary body can increase outflow, decreasing the formation of the vitreous humor

50
Q

What drugs can be used to treat glaucoma?

A

Pilocarpine (muscarinic agonist, short acting)

Physostigmain (anticholinesterase, longer acting)

51
Q

What drugs can be used to treat Xerostomia?

A

Pilocarpine
Cevimeline
both are muscarinic agonists

52
Q

How can muscarinic agonists treat Xerostomia?

A

Increase outflow in the parotid, submandibular, and sublingual secretion
Max flow occurs in 30 min, and return to basal flow in 3 hours
Ususally no significant effect on cardiac function or BP

53
Q

What can be used to reverse neuromuscular blocks?

A

Anticholinesterases can be used to terminate neuromuscular block of curare-like agents in general anesthesia

54
Q

What clinical features affect the choice of an anti-muscarinic drug?

A

Differing intensity of effect in different organs
CNS contribution
Differences in action of subtypes
Onset and duration of action

55
Q

Treatment with an anti-muscarinic does what to the target? What is an exception?

A

It places the target under sympathetic control, because anti-muscarinics block parasympathetics
The only exception is the sweat gland -signal comes from the symp and p-symp and act upon muscarinic receptors at the target and both are blocks

56
Q

What pharmacological effects do anti-muscarinics have on the eye?

A

Will cause pupil dilation and paralysis of accomodation

Usually dont cause rise in intraocular pressure, except will raise pressure in narrown angle glaucoma

57
Q

What pharmacological effects do anti-muscarinics have on respiratory tracts?

A

Used to produce bronchodilation and diminish mucous production to treat COPD

58
Q

What pharmacological effects do anti-muscarinics have on body temperature?

A

Inhibit sweating, which can elevate body temperature

59
Q

What pharmacological effects do anti-muscarinics have on the GI tract?

A

Inhibit motility

Inhibit gastric secretions at very high concentrations

60
Q

What pharmacological effects do anti-muscarinics have on secretory glands?

A

Block parasympathetic mediated secretion

61
Q

What pharmacological effects do anti-muscarinics have on the heart?

A

Mild bradycardia seen with oral anti-muscarinics used to limit salivation
-this is due to selective inhibition of prejunctional M2 receptors that limit AcCh release

62
Q

What pharmacological effets do anti-muscarinics have on the urinary tract?

A

Detrusor muscles are relaxed by atropine
Sphincter and trigone muscles are contracted by atropine
These cause urinary retention

63
Q

What are some theraputic uses for anti-muscarinics?

A

Dilate pupils for opthalmic procedures
Treatment of COPD
diminish salivary secretion before oral procedures
Anti-spasmodics and anti-ulcer treatment (not useful b/c of side effects)
Antidote to anticholinesterases

64
Q

What are major adverse effects of Atropine?

A 
Increased intraocular pressure
Ventricular fibrilation
Tachycardia
Dizziness
Neausea
Dry mouth
Blurred vision
Extreme confusion and hallucinations
65
Q

What are anti-cholinergic toxidrone symptoms?

A 
Warm, dry skin from decreased sweating
Blurry vision
Decreased sweating/lacrimation
Vasodilation
Effects on the CNS
66
Q

What mediates AcCH Nicotinic receptors?

A

The CNS

67
Q

Nicotinic receptors mediate what?

A

Transmission of sympathetic and parasympathetic nerve impulses
Postsynaptic transmission of nerve impulses at skeletal muscles

68
Q

T/F - nicotinic receptors can have CNS effects

A

True - they can cross the BBB to produce a feeling of well being and decreased irritability

69
Q

Succinylcholine

A

Depolarizing blocking agent

More rapid onset of action and a shorter duration than non-depolarizing blocking agents

70
Q

What are the two phases Succinylcholine works in

A 
Phase 1 (short acting)
Phase 2 (long acting)
71
Q

Phase 1 of Succinylcholine function

A

Short acting
Activates AcCh receptors
But the chronic depolarization at the muscle end-plate leads to inactivation of Na channels and flaccid paralysis

72
Q

Phase 2 of Succinylcholine function

A

Long acting

Chronic exposure succinylcholine leads to desensitization of AcCh receptors

73
Q

What are some theraputic uses of neuromuscular blocking agents?

A

Endotracheal intubation
Adjuct to general anesthesia during surgery to block neuromuscular transmission
Brachoscopy
Relax vocal chords

74
Q

What are adverse effects of neuromuscular blockers?

A

Respiratory failure is the most significant
Arrythmias
Bradycardia

75
Q

Dental application for neuromuscular blockers

A

Occasionally need to produce jaw relaxation when performing surgery

AU15 - Pharmacology Test 2 (10 decks)

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