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MS 2 - Unit 2 > Pharmacology - Autonomics II and III > Flashcards

Pharmacology - Autonomics II and III Flashcards

1
Q

M1/M3/M5 receptors couple to:

A

phospholipase C

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2
Q

M2/M4 receptors couple to:

A

adenylyl cyclase and/or K+ channels

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3
Q

Are M2 autoreceptors excitatory or inhibitory?

A

Inhibitory
utilize signaling pathways identical to M2 receptors in the heart - cAMP reduction and K+ channel activation
*decreases HR

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4
Q

Pilocarpine is a nonselective muscarinic ______.

A

agonist

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5
Q

Direct-acting cholinomimetic agents bind to and directly activate muscarinic or nicotinic receptors. The indirect agents act by:

A

inhibiting the action of acetylcholinesterase –> increase endogenous ACh in the synaptic clefts and neuroeffector junctions

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6
Q

Some cholinesterase inhibitors have a moderate direct action, for example some quaternary carbamates like ____

A

Neostigmine

active NM nicotinic cholinoceptors in addition to blocking cholinesterase

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7
Q

Bethanechol is used for:

A

postoperative and neurogenic ileus and urine retention
relieves paralysis of GI/GU tract
carbamic acid ester

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8
Q

Direct muscarinic effects of direct-acting choliniceptor stimulants:
Eye - sphincter muscle of iris

A

contraction (miosis)

muscarinic agonists can reduce intraocular pressure by causing contraction of the ciliary body so as to facilitate outflow of aqueous humor and perhaps also its rate of secretion…Pilocarpine, a well-absorbed, tertiary amine, can be used for this.

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9
Q

Direct muscarinic effects of direct-acting choliniceptor stimulants:
Eye - ciliary muscle

A

contraction for near vision

muscarinic agonists can reduce intraocular pressure by causing contraction of the ciliary body so as to facilitate outflow of aqueous humor and perhaps also its rate of secretion…Pilocarpine, a well-absorbed, tertiary amine, can be used for this.

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10
Q

Direct muscarinic effects of direct-acting choliniceptor stimulants:
Heart - SA node

A

Negative chronotropy
HR down
M2

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11
Q

Direct muscarinic effects of direct-acting choliniceptor stimulants:
Heart - Atria

A

decrease in contractile strength - negative inotropy
_______ in refractory period
M2

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12
Q

Direct muscarinic effects of direct-acting choliniceptor stimulants:
Heart - AV node

A

decrease in conduction velocity - negative dromotropy
increase in refractory period
M2

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13
Q

Direct muscarinic effects of direct-acting choliniceptor stimulants:
Heart - ventricles

A

small decrease in contractile strength

M2

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14
Q

Direct muscarinic effects of direct-acting choliniceptor stimulants:
Arteries and veins

A

dilation via NO (EDRF)

constriction is high dose direct effect

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15
Q

Direct muscarinic effects of direct-acting choliniceptor stimulants:
Bronchial muscle

A

contraction/bronchoconstriction

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16
Q

Direct muscarinic effects of direct-acting choliniceptor stimulants:
GI tract - motility

A

increase

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17
Q

Direct muscarinic effects of direct-acting choliniceptor stimulants:
GI sphincters

A

relaxation

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18
Q

Direct muscarinic effects of direct-acting choliniceptor stimulants:
GI secretion

A

stimulation

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19
Q

Direct muscarinic effects of direct-acting choliniceptor stimulants:
Urinary bladder - detrusor muscle

A

contraction

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20
Q

Direct muscarinic effects of direct-acting choliniceptor stimulants:
Urinary bladder - Trigone and sphincter

A

relaxation

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21
Q

Direct muscarinic effects of direct-acting choliniceptor stimulants:
sweat, salivary, lacrimal, nasopharyngeal

A

secretion (SLUDGE)

M3

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22
Q 
Neostigmine
Tacrine
Donepezil
Edrophonium 
Physostigmine
Pyridostigmine

These drugs are examples of:

A

cholinesterase inhibitors

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23
Q 
Isoflurophate
Sarin
Echothiophate
Parathion
Paraoxon

These drugs are examples of:

A

Organophosphate cholinesterase inhibitors

Poisons, insecticides and nerve gases

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24
Q

Sarin gas poisoning can be reversed by pralidoxime because:

A

Pralidoxime (PAM) is a strong nucleophile that regenerates acetylcholinesterase

**must work before “aging” which makes acetylcholinesterase permanently/irreversibly inactive

Sarin gas takes only 2 minutes to age, so administer quickly

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25
Q

Explain the effect of Neostigmine on muscle strength at LOW doses.

A

Increases ACh level

Under or overdoses in MG patients cause paralysis

26
Q

Explain the effect of Neostigmine on muscle strength at HIGH doses.

A

Depolarizing block

Under or overdoses in MG patients cause paralysis

27
Q

Major uses for cholinomimetics:

A

diseases of the eye ie glaucoma;
GI and urinary tension (is post-surgical atony, neurogenic bladder, impaired salivation);
NMJ issue ie MG, reversal of non-depolarizing blocker-induced neuromuscular paralysis;
cognitive enhancement in Alzheimer’s

28
Q

What drug can be used as a diagnostic tool for confirming MG in patients?

A

Edrophonium

transiently increases muscle strength, can be given IV to test

29
Q

SLUDGE effects can be reversed by administering:

A

Atropine (and pralidoxime (PAM))

30
Q

SLUDGE plus what symptoms characterize major cholinomimetic toxicity (as with suicide attempts)?

A

Respiratory collapse from CNS effects;
skeletal muscle paralysis;
bronchospasm

31
Q

Duration of action:

Edrophonium - MG and Ileus

A

5-15 minutes

32
Q

Duration of action:

Neostigmine - MG and Ileus

A

30 min to 2 hours

33
Q

Duration of action:

Pyridostigmine - MG

A

3-6 hours

34
Q

Duration of action:

Physostigmine - Glaucoma

A

30 min to 2 hours

35
Q

Duration of action:

Echothiophate - Glaucoma

A

100 hours

36
Q

What are the sites of action of the ganglionic blockers, Nn?

A

Adrenal medulla;
Norepi nicotinic receptor;
ACh nicotinic receptor

37
Q

Does atropine bind to nicotinic receptors?

A

No, while it is structurally similar to ACh, it binds only at muscarinic GPCRs.

38
Q

In general, tertiary amines are better absorbed and _______ than quaternary amines

A

penetrate the CNS better

have more central effects

39
Q

Give an example of a quaternary amine that has local effects but is too big to diffuse and affect the CNS.

A

Glycopyrrolate

40
Q

0.5mg of atropine has what effects?

A

slight cardiac slowing
drymouth
inhibition of sweating (cholinergic)

41
Q

5mg of atropine has what effects?

A 
rapid HR
palpitations
market drymouth
dilation of pupil (mydriasis) --> "belladonna"
blurring of near vision
42
Q

10mg and up of atropine has what effects?

A

hallucinations and delirium

coma

43
Q

Effects of Muscarine BLOCKING drugs:
CNS
–muscarinic subtypes unknown

A 
sedation
anti-motion sickness action
anti-Parkinsonian action
amnesia
delirium
44
Q

Effects of Muscarine BLOCKING drugs:
Eye
M3 receptors

A

Cycloplegia - paralysis of the ciliary muscle of the eye, resulting in a loss of accommodation;
mydriasis

45
Q

Effects of Muscarine BLOCKING drugs:
Bronchi
M3 receptors

A

Bronchodilation, especially if constricted

46
Q

Effects of Muscarine BLOCKING drugs:
GI
M1 and M3 receptors

A

relaxation

slowed peristalsis

47
Q

Effects of Muscarine BLOCKING drugs:
GU tract
M3 receptors

A

relaxation of bladder wall

urinary retention

48
Q

Effects of Muscarine BLOCKING drugs:

Heart

A

initially slight bradycardia at low doses - block of inhibitory presynaptic receptors
then tachycardia - block M2 receptors at SA node

49
Q

Effects of Muscarine BLOCKING drugs:
Blood vessels
M3 receptors on endothelium

A

block muscarinic vasodilation with NO

will not manifest unless a muscarinic agonist is present

50
Q

Effects of Muscarine BLOCKING drugs:
Glands
M1 and M3 receptors

A

reduction in salivation, lacrimation, sweating,

51
Q

Effects of Muscarine BLOCKING drugs:

Skeletal muscle

A

NONE!!! This is NMJ

52
Q

Hexamethonium
Mecamylamine
these drugs are:

A

Ganglion-blocking drugs
not really used therapeutically anymore
used to be used to prevent bleeding out by dropping BP on the battlefield

Ganglionic blockers competitively inhibit Nn receptors at both sympathetic and parasympathetic ganglia. Lack of selectivity –> side effects

53
Q

NMJ blockers inhibit what kind of receptor?

A

Nm

54
Q

Give an example of a nondepolarizing NMJ blocker.

A

Tubocurarine
Mivacurium
prevents opening of the end plate channel

55
Q

Give an example of a depolarizing NMJ blocker.

A

Succinylcholine
“desensitize” the end plate by causing persistent depolarization
flaccid paralysis

56
Q

Succinylcholine is made up of:

A

2 molecules of acetylcholine linked
AGONIST of NMJ (initial contractions)
**action is brief - 5-10 min
Hydrolyzed by butyrylcholinesterase in the plasma en route to site of action

57
Q

Uses for NMJ blockers:

A

surgery prep

intubation prep

58
Q

Length of effects - Tubocurarine

A

30-60 min

Mivacurium is much shorter bc hydrolyzed more rapidly

59
Q

Toxic effects of NMJ blockers:
Tubocurarine
Succinylcholine

A

respiratory paralysis

disturbance of autonomic function (Nn overlap effects)

60
Q

Pancuronium used in:

A

lethal injection. It’s a NMJ blocker

used with sodium thiopental and potassium chloride

61
Q

Botulinim Toxin A degrades what protein?

A

SNAP-25 which mediates fusion of synaptic vesicles with the presynaptic terminal membrane –> AP can’t get ACh released

useful in treating diseases with pathologic muscular tone (locally injected) - ie achalasia, strabismus, oromandibular dystonia (spasms of face/jaw/neck)

MS 2 - Unit 2 (26 decks)

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