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AU15 - Pharmacology Test 2 > Cholinergic Drugs > Flashcards

Cholinergic Drugs Flashcards

(75 cards)

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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
What pharmacological effects do muscarinic receptors have on the eye?
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
26
What pharmacological effects do muscarinic receptors have on the heart?
Cardiac muscles contain M2 receptors | Activation reduces cardiac output
27
What pharmacological effects do muscarinic receptors have on vasodilation?
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
28
What pharmacological effects do muscarinic receptors have on bronchoconstriction?
M3 muscarinic receptors on the bronchial muscle mediate contraction
29
What pharmacological effects do muscarinic receptors have on GI tracts?
Mostly contractile | However, M2 receptors relax the sphincter muscles
30
What pharmacological effects do muscarinic receptors have on secretory glands?
M3 receptors lead to the release of Ca | This release stimulates the release of glandular contents from the secretory glands
31
What pharmacological effects do muscarinic receptors have on the Urinary tract?
M3 muscarinic receptors mediate detrusor muscle contraction - this aids in the voiding of bladder
32
What pharmacological effect do muscarinic receptors have on the CNS?
There are CNS effects, but they are complex and not part of common theraputic strategies
33
Which are absorbed better, tertiary or quaternary amines?
Tertiary, because they are uncharged. Quaternary amines are charged
34
Why are the effects of AcCh effects so quick?
Because AcCh is rapidly hydrolyzed
35
What patients have an increased risk of adverse effects of muscarinic agonists?
Patients with asthma Patients with cardiovascular disease Patients with ulcers
36
What are some adverse effects of activated muscarinic receptors?
``` SLUD responses (Salivation, Lacrimation, Urination, Defication) Hypertensive response ```
37
Acetylcholinesterase
An enzyme that hydrolyzes Ach into Acetic acid and choline
38
MOA
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
T/F - Some "reversible" anticholinesterases are rapidly hydrolyzed by cholinesterase
False - they are slowly hydrolyzed by cholinesterase
40
T/F - Anticholinesterases act in a unidirectional manner
False - Some anticholinesterases act in a rapidly reversible manner
41
What are Malathian and Sarin
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
Anticholinesterase drugs produce effects that are similar to what?
Cholinergic agonists | because they increase the concentration of ACh at the effector site
43
Greater cholinergic stimulation leads to what?
The greater the effect
44
Why do anticholinesterases not produce muscarinic receptor mediated vasodilation? How can we produce vasodilatory effects?
There is no parasympathetic innervation of vascular endothelium Can produce vasodilatory effects through autonomic ganglia
45
What effects can Physostigmine produce?
Vasodilatory effects in the CNS
46
Where is Physostigmine absorbed?
After oral subcutaneous and topical administration
47
What are some theraputic uses for cholinergic agonists and anticholinesterases?
``` Glaucoma Xerostomia Reversal of neuromuscular block Myasthenia Gravis Cross the BBB to improve cognitive function of Alzheiemer's patients ```
48
What is glaucoma?
Atrophy of the optic nerve and loss of vision due to elevation in intraocular pressure
49
How can cholinergic agonists and anticholinesterases treat glaucoma?
Stimulating musculature of the iris and ciliary body can increase outflow, decreasing the formation of the vitreous humor
50
What drugs can be used to treat glaucoma?
Pilocarpine (muscarinic agonist, short acting) | Physostigmain (anticholinesterase, longer acting)
51
What drugs can be used to treat Xerostomia?
Pilocarpine Cevimeline both are muscarinic agonists
52
How can muscarinic agonists treat Xerostomia?
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
What can be used to reverse neuromuscular blocks?
Anticholinesterases can be used to terminate neuromuscular block of curare-like agents in general anesthesia
54
What clinical features affect the choice of an anti-muscarinic drug?
Differing intensity of effect in different organs CNS contribution Differences in action of subtypes Onset and duration of action
55
Treatment with an anti-muscarinic does what to the target? What is an exception?
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
What pharmacological effects do anti-muscarinics have on the eye?
Will cause pupil dilation and paralysis of accomodation | Usually dont cause rise in intraocular pressure, except will raise pressure in narrown angle glaucoma
57
What pharmacological effects do anti-muscarinics have on respiratory tracts?
Used to produce bronchodilation and diminish mucous production to treat COPD
58
What pharmacological effects do anti-muscarinics have on body temperature?
Inhibit sweating, which can elevate body temperature
59
What pharmacological effects do anti-muscarinics have on the GI tract?
Inhibit motility | Inhibit gastric secretions at very high concentrations
60
What pharmacological effects do anti-muscarinics have on secretory glands?
Block parasympathetic mediated secretion
61
What pharmacological effects do anti-muscarinics have on the heart?
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
What pharmacological effets do anti-muscarinics have on the urinary tract?
Detrusor muscles are relaxed by atropine Sphincter and trigone muscles are contracted by atropine These cause urinary retention
63
What are some theraputic uses for anti-muscarinics?
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
What are major adverse effects of Atropine?
``` Increased intraocular pressure Ventricular fibrilation Tachycardia Dizziness Neausea Dry mouth Blurred vision Extreme confusion and hallucinations ```
65
What are anti-cholinergic toxidrone symptoms?
``` Warm, dry skin from decreased sweating Blurry vision Decreased sweating/lacrimation Vasodilation Effects on the CNS ```
66
What mediates AcCH Nicotinic receptors?
The CNS
67
Nicotinic receptors mediate what?
Transmission of sympathetic and parasympathetic nerve impulses Postsynaptic transmission of nerve impulses at skeletal muscles
68
T/F - nicotinic receptors can have CNS effects
True - they can cross the BBB to produce a feeling of well being and decreased irritability
69
Succinylcholine
Depolarizing blocking agent | More rapid onset of action and a shorter duration than non-depolarizing blocking agents
70
What are the two phases Succinylcholine works in
``` Phase 1 (short acting) Phase 2 (long acting) ```
71
Phase 1 of Succinylcholine function
Short acting Activates AcCh receptors But the chronic depolarization at the muscle end-plate leads to inactivation of Na channels and flaccid paralysis
72
Phase 2 of Succinylcholine function
Long acting | Chronic exposure succinylcholine leads to desensitization of AcCh receptors
73
What are some theraputic uses of neuromuscular blocking agents?
Endotracheal intubation Adjuct to general anesthesia during surgery to block neuromuscular transmission Brachoscopy Relax vocal chords
74
What are adverse effects of neuromuscular blockers?
Respiratory failure is the most significant Arrythmias Bradycardia
75
Dental application for neuromuscular blockers
Occasionally need to produce jaw relaxation when performing surgery

AU15 - Pharmacology Test 2 (10 decks)

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