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Pharmacology FINAL > Lecture 8 Part 2 > Flashcards

Lecture 8 Part 2 Flashcards

1
Q

what is the action of indirect acting cholinomimetics

A

they prevent the hydrolysis of acetylcholine by INHIBITING ACETYLCHOLINESTERASE

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2
Q

Name 3 types of structures that are indirect acting cholinomimetics

A

simple alcohols with a quaternary ammonium group** (edrophonium)

organophosphates

carbamic acid esters of alcohols that have quaternary or tertiary ammonium gorups

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3
Q

what is edrophonium

A

a simple alcohol with a quaternary ammonium group

an indirect acting cholinomimetic

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4
Q

what is echothiophate

A

an organophosphate

indirect acting cholinomimetic

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5
Q

what is neostigmine

A

a carbamic acid ester (carbamate) of an alcohol with quaternary or tertiary ammonium groups that is an indirect acting cholinomimetic

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6
Q

carbaryl

A

cholinesterase inhibitor (indirect cholinomimetic)

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7
Q

physostigmine

A

cholinesterase inhibitor (indirect acting cholineomimetic)

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8
Q

what is the action of organophosphates

A

cause all secretions to occur - pesticides

through inhibiting acetylcholine esterase - INDIRECT acting

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9
Q

name 4 organophosphate cholinesterase inhibitors

A

sarin
paraoxon (parathion)
malaoxon (malathion)
echothiophate

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10
Q

true or false

organophosphates are direct acting

A

FALSE

indirect acting cholinomimetics - inhibit acetylcholine esterase

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11
Q

true or false

organophosphates inhibit acetylcholine esterase

A

true

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12
Q

indirect acting cholinomimetics target acetylcholinesterases as well as….

A

butyrylcholnesterases

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13
Q

explain the mechanism of action of quaternary alcohols and give an example of one

A

edrophonium

reversibly binds electrostatically and hydrogen bonds to the active site of the ACHE receptor to prevent it from accessing acetylcholine and hydrolyzing it

NOT A COVALENT BOND - short lived (2-10mins)

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14
Q

explain the difference in the duration of actions of:

-carbamate esters
-organophosphates
-quaternary alcohols

A

all bind ACHE to prevent it from accessing acetylcholine, thus having indirect cholinomimetic effects

quaternary alcohols have the shortest duration, 2-10 minutes. bond is via electrostatic and hydrogen bonds to the active site

next is carbamate esters. attaches covalently to ACHE and is considerably more RESISTANT. duration is 30mins - 6 hours

longest = organophosphates. undergo initial binding and hydrolysis by the enzyme - results in a PHOSPHORLYATED ACTIVE SITE. covalent phosphate-enzyme bond is extremely stable and hydrolyzes in water at a VERY SLOW RATE (hundreds of hours - aging)

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15
Q

name a carbamic acid (carbamate) ester and state its duration of action

A

neostigmine
30 mins - 6 hours
covalently bound to ACHE

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16
Q

the duration of action of carbamates is determined by…….

A

inhibitor-enzyme complex

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17
Q

what is physostigmine

A

a carbamate (indirect acting)

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18
Q

explain the absorption of quaternary carbamates

A

poor absorption bc of charge
a lot of dose is needed if they are to be administered orally

an exception is physostigmine, which is NO CHARGE

thus, it is well absorbed from alll sites and can be used in the eye
bad side is that it also distributes in the CNS and is thus more toxic

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19
Q

explain the absorption of organophosphate cholinesterase inhibitors and any exceptions

A

all except echothiophate is well absorbed from the skin, gut, lung, and eye

all except echothiophate are distributed to all parts of body INCLUDING CNS – thus CNS toxicity is a poisoning component

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20
Q

explain the half life of organophosphate cholinesterase inhibitors

A

short half life

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21
Q

therapeutic use of edrophonium

A

treatment of myasthenia gravis (ACH not there and degrades so quickly)

ileus, arrhythmias

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22
Q

approximate duration of action of edrophonium

A

5-15 mins

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23
Q

what does neostigmine treat?
also give approximate duration of action

A

myasthenia gravis, ileus, arrhythmias

a carbamate, duration is 0.5-4 hours

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24
Q

what does pyridostigmine treat and what is its duration of action

A

myasthenia gravis
4-6 hours (carbamate)

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25
Q

what does physistigmine treat?
approximate duration of action

A

glaucoma
contraction of ciliary body to redeuce intraocular pressure and facilitate outflow of aqueous humor and diminish its secretion

0.5-2 hours (carbamate)

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26
Q

what does echothiophate treat and what is its approximate duration of action

A

glaucoma
100 hours (organophosphate)

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27
Q

besides cholinesterase inhibitors, what other drugs can be used to treat glaucoma?

A

muscarinic stimulants

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28
Q

explain the mechanism of how muscarinic stimulants and cholinesterase inhibitors treat glaucoma

A

glaucoma symptom is INCREASED intraocular pressure

these drugs decrease the intraocular pressure by contracting the ciliary body and causing the aqueous humor to flow away and possibly shorten the rate of its secretion

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29
Q

direct cholino agonists and cholinesterase inhibitors have been largely replaced by…….

A

prostaglandin derivatives and topical beta blockers

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30
Q

as mentioned, cholinergic agonists and indirect cholinomimetics have been largely replaced by prostaglandin derivatives and topical beta blockers

name 1 condition that they are currently still used for

A

cholinomimetic agonists are used to treat esotropia - strabismus (eye misalignment) in young children

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31
Q

if someone suffers from dry mouth, what drug(s) should be used?

A

acetylcholine agonists or ACHE inhibitors

enhance activity of PSNS
specifically pilocarpine

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32
Q

_________ is used in dry mouth to increase salivary secretion

give brand and generic name

A

pilocarpine (salagen)

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33
Q

name 2 drugs for postoperative ileus (paralysis/atony of stomach or bowel) and for urinary retention conditions, and to increase the town of lower esophageal sphincter in pts with reflux esophagus

A

bethanechol and neostigmine

proton pump inhibitors preferred for reflux esophagus tho

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34
Q

brand name of pilocarpine

A

SALAGEN

35
Q

Myasthenia gravis is what kind of disease and what does it affect?

A

autoimmune disease that affects neuromuscular junctions of skeletal muscle

36
Q

name some symptoms of myasthenia gravis

A

ptosis
diplopia
difficulty speaking/swallowing
weakness of extremities

37
Q

explain the mechanism of myasthenia gravis

A

antibodies produced against a1 subunits of the nicotinic receptor channel complex

not enough ACH action

38
Q

what drugs are exremely valuable as therapy for myasthenia gravis?

A

cholinesterase inhibitors like neostigmine and edrophonium

long term with pyridostigmine or neostigmine

39
Q

what drug was used to treat supraventricular tachyarrhymias?

what is used now?

A

edrophonium **
short acting cholinesterase inhibitor

now, calcium channel blockers are used

40
Q

what drug should be administered to someone who has taken too much of an antimuscaranic drug and is now suffering toxic effects?

what are some of these toxic effects?

give 2 examples of
antimuscarinic drugs that can cause these effects

A

administer PHYSOSTIMGINE with close monitoring

severe behavioral disturbances
arrhythmia in adults

atropine, tricyclic antidepressants

41
Q

someone has taken too much of direct acting muscarinic stimulants. name 2 potential drugs this could be.

what symptoms will be observed?

what is the treatment for this?

A

pilocarpine and choline esters

nausea, vomiting, diarrhea, urinary urgency, salivation, sweating, cutaneous vasodilation, bronchial constriction

treatment is ATROPINE 1-2mg parenterally — it is a cholinergic antagonist

42
Q

someone has taken too much acetylcholine and is experiencing negative side effects such as vomiting and diarrhea.

what should be given

A

atropine 1-2mg parenterally

43
Q

which is more important - acute nicotine poisoning or chronic?

A

chronic is more important bc of cancer risk and COPD risk

44
Q

what are neonicotinoids?

A

synthetic compounds that cause nicotine toxicity in insects. it’s an insecticide

45
Q

what is the fatal dose of nicotine?
why have more smokers not died from nicotine poisoning?

A

40mg or 1 drop of pure liquid

most of the nicotine in cigs is destroyed by burning or escapes via sidestream smoke

46
Q

the toxic dose of nicotine is 40mg of 1 drop of pure liquid

how have more kids not died from inhaling nicotine insecticides or smoke?

A

vomitting immediately follows, limiting the absorption

47
Q

explain 3 components of acute nicotine toxicity

A

it’s a CNS stimulant - causes convulsions that can bcome resp arrest/coma

respiratory paralysis - skeletal muscle depolarization blockade

hypertension and arrhythmias

48
Q

name 3 things that can be used to treat acute nicotine toxicities

A

atropine - to reverse the muscarinic effects

diazepam (anticonvulsant)

mechanical ventilation for the neuromuscular blockade

49
Q

nicotine works on what receptor

A

nicotinic

50
Q

name 5 components of chronic nicotine toxicity

A

lung cancer
COPD
stroke
asthma
reproductive effects (low birth weight, premature bb)
diabetes
other cancer

51
Q

name 2 drugs that can be used to stop smokine

A

varenicline - partial nicotinic agonist

buproprion - antidepressant

52
Q

name some adverse effects of varenicline

A

nausea
insomnia
exacerbation of psychiatric illness - inc anx and depression

53
Q

symptoms of cholinesterase inhibitor toxicity

A

TOO MUCH ACH

muscarinic effects: miosis (pupil constriction), salivation, bronchial constriction, vomiting, diarrhea, CNS convulsions, coma

nicotinic effects - depolarizing neuromuscular blockade

54
Q

name 2 types of drugs that are available as pesticides in the US

A

organophosphates

cholinesterase inhibitors

55
Q

what drugs were used as chemical warfare agents and why?

A

the cholinesterase inhibitors - soman, sarin, VX

they induced effects rapidly bc of their large concentrations

56
Q

Treatment for cholinesterase inhibitor toxicity

A

parenteral atropine in large doses as often as required for muscarine excess

watch vital signs - respiration may be impaired

decontamination to prevent further absorption - remove clothes, wash skin, etc

57
Q

what are soman, sarin, and VX

A

cholinesterase inhibitors used in chemical warfare

58
Q

besides atropine, what other drugs may be used for cholinesterase inhibitor toxicity?

A

pralidoxime
benzodiazepine for seizures

59
Q

what is the effect of binding to muscarinic cholinoceptors

A

parasympathetic nerve stimulation

60
Q

what is the effect of binding to nicotinic cholinoceptors

A

autonomic ganglia and skeletal muscle motor end plate are stimulated

61
Q

what happens when muscarinic agonists are instilled into the conjunctival sac of the eye?**

A

-smooth muscle of the iris sphincter contracts (pupil constriction - miosis)

-ciliary muscle contracts - resulting in accomadation, aquous humor output

USED TO TREAT GLAUCOMA

62
Q

Low doses of Ach cause vaso____.

what does this result in

A

vasodilation

causes a reduction in blood pressure — and a reflex increase heart rate to increase it

63
Q

LARGE doses of acetylcholine do what to the heart?

A

bradycardia (slow heart beat)
decreased AV node conduction velocity
hypotension

hyperpolarization
REDUCED action potential duration
decreased contractility of atrial and ventricular cells

64
Q

as mentioned, acetylcholine in low doses causes vasodilation

this vasodilation occurs via what mechanism?

A

activation of M3 receptors

65
Q

what is interesting about the cardiovascular effect of pilocarpine?

A

in general, cholinomimetics have similar effects to acetylcholine

however, pilocarpine is an exception bc when given IV it may produce HYPERTENSION after a brief initial hypotensive response

66
Q

what do muscarinic stimulants do to the respiratory system

A

bronchoconstriction

67
Q

which glands in the GI tract are stimulated the MOST when muscarinic agonists are adminsitered?
which are stimulated less?

A

most - salivary and gastric glands

pancreas and small intestine glands stimulated less

68
Q

true or false

when muscarinic agonists are administered, peristaltic activity is decreases and most sphincters are contracted

A

FALSE - REST AND DIGEST

peristaltic activity is increased and most sphincters are RELAXDED

69
Q

what happens to the genitourinary tract when muscarinic agonists are administered

A

detrusor muscle is stimulated
trigone and sphincter muscles relaxx

voiding is promoted

70
Q

true or false

muscarinic agonists stimulate secretion by THERMOREGULATORY sweat glands, lacrimal, and nasopharyngeal glands

A

true

71
Q

true or false

the CNS contains both nicotinic and muscarinic receptors.
the brain is richer in nicotinic sites and the spinal cord contains mostly muscarinic sites

A

FALSE

CNS does contain both but brain is richer in muscarinic sites and spinal cord in nicotinic sites

72
Q

what is M1 receptor involved with in the brain

A

cognition

73
Q

what is M2 receptor involved with in the brain

A

nociception and thermoregulation

74
Q

what is M3 involved with in the brain

A

decreased appetite/body fat

75
Q

_____ receptors allow ACh and nicotine to regulate the release of what 5 neurotransmitters?**

A

presynapticn nicotine receptors
glutamate
serotonin
GABA
dopamine
Norepinephrine

76
Q

chronic exposure to nicotine has a DUAL EFFECT at nicotinic receptors

explain this statement

A

there is activation (depolarization) followed by DESENSITIZATION

77
Q

What is the reason for nicotine addiction

A

activation of nicotinic receptors releases dopamine in the mesolimbic system

78
Q

in high concentrations, nicotine induces ___, ____, and stimulation of the ______

A

tremor, emesis, and stimulation of the respiratory center

79
Q

effect of nicotine on the cardiovascular system**

A

sympathomimetic
hypertension and increased heart rate

80
Q

effect of nicotine on GI and urinary tracts**

A

parasympathomimetic

increased motility, nausea, vomiting, diarrhea, voiding

81
Q

effect of nicotine on neuromuscular junction

A

depolarization of the end plate. causes muscle contraction

if the action persists, depolarization blockade, resulting in flaccid paralysis (weakness) of skeletal muscles

82
Q

the nicotine action on BOTH parasympathetic and sympathetic ganglia resembles….

A

simultaneous discharge of of PSNS and SNS

ie: cardiovasular is sympathomimetic and GI/urinary and parasympathomimetic

83
Q
A

Pharmacology FINAL (11 decks)

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