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Pharmacology > Exam II: Cholinergic Agonists > Flashcards

Exam II: Cholinergic Agonists Flashcards

1
Q

Cycle of ACh (All 6 steps)

A
  1. ACh made from acetyl-CoA and choline
  2. ACh stored in neurons (“quanta”)
  3. Release of ACh when neurons stimulated by an action potential
  4. ACh binds to ACh-R
  5. AChE breaks down ACh
  6. Acetyl-CoA and choline recycled
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2
Q

What are the two types of cholinergic receptors?

A

Muscarinic

Nicotinic

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3
Q

Are muscarinic receptors found in the sympathetic or parasympathetic nervous system…or both?

A

Parasympathetic

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4
Q

Where are nicotinic receptors found ( in terms of nervous system…not specific organ )

A

Ganglionic level of both parasympathetic and sympathetic sides of ANS

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5
Q

Do nicotinic receptors have inhibitory capabilities?

A

No. They only relay the efferent message sent from CNS

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6
Q

If a cholinomimetic agent acts to stimulate it is an ______. In contrast, if an cholinomimetic agent acts to inhibit it is an ______.

A

Direct agonist

```
Indirect agonist
by preventing breakdown of ACh
~~~

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7
Q

What are the two groups of direct-acting cholinomimetics?

A
  1. Esters of Choline

2. Alkaloids

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8
Q

List 4 examples of choline esters

A
  1. ACh
  2. Bethanechol
  3. Carbachol
  4. Methacholine
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9
Q

List 4 examples of alkaloids

A
  1. Lobeline
  2. Muscarine
  3. Nicotine
  4. Pilocarpine
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10
Q

What are the characteristics of choline esters?

A
  1. Hydrophillic
    (they poorly penetrate BBB b/c of their methyl groups pulling electrons and causing a positive charge
  2. Hydrolized by AChE
  3. Above properties vary on chemical structure
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11
Q

All alkaloids are _______ except for _____ which is a ___________.

A

Tertiary amines
Muscarine
quartenary amine

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12
Q

All choline esters are ________.

A

Quarternary ammoniums

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13
Q

What are the characteristics of direct acting alkaloids?

A
  1. Well absorbed after oral administration
  2. Lipid soluble –> allows for a larger VD
  3. NOT susceptible to AChE
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14
Q

What are the three types of AChE inhibitors?

A
  1. Simple alcohols
  2. Carbamate Esters
  3. Organophosphates
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15
Q

Contrast the three AChE inhibitor’s binding effects

A

Simple alcohols = bind weakly and reversibly
–> half life is very short (< 10 min)

Carbamate Esters = bind reversibly but stronger than simple alcohols
–> half life from 30 min to 6 hours

Organophosphates = covalent bonds make it nearly irreversible
–> half-life lasts hundreds of hours

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16
Q

Describe the effects cholinomimetics have on the eye and what these effects facilitate.

A
  1. Iris sphincter smooth muscle - contraction, causing miosis (pupil constriction)
  2. Ciliary muscle –> contraction (accomodation)

These facilitate aqueous humor flow from the anterior chamber and alter the amount and focus of light reaching the retina

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17
Q

What drugs are used to treat glaucoma? Describe the type of these drugs.

A

Pilocarpine (muscarine agonist)

Physostigmine (carbamate ester…AChE inhibitor)

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18
Q

Describe the effects cholinomimetics have on the respiratory system.

Do we use cholinomimetics to treat respiratory conditions?

A

Cause contraction of bronchiole muscles and stimulate secretion of bronchiole glands (inc. mucous)

We do not use cholinomimetics to tx respiratory conditions

19
Q

Describe the effects cholinomimetics have on the GI system

A

Increase motility (peristalsis), increase secretion, and relax sphincter muscles

20
Q

What is a GI disorder in which you would use a cholinomimetic to tx

A

Post-operative ileus –> use neostigmine (AChE inhibitor)

21
Q

Describe the effects of cholinomimetics on the GU system

A

Detrusor muscle –> contraction

Trigone and sphincter –> relaxation

22
Q

What are cholinomimetics can be used to treat urinary retention?

A

Bethanecol (Choine ester…direct acting)

Neostigmine (Carbamate ester…indirect acting)

23
Q

What secretory glands do muscarine agonists stimulate?

A
  1. Sweat glands –> diaphoresis
  2. Salivary glands
  3. Lacrimal glands
  4. Nasopharyngeal glands –> snot
24
Q

Muscarinic receptors in the CNS are found to:

A
  1. Induce tremor
  2. Cause hypothermia
  3. Interfer w/ nocieption (ability to sense stimuli)
25
Q

Nicotinic receptors in the CNS are found to:

A
  1. Induce tremor
  2. Stimulate emesis (vomitting)
  3. Stimulate respiratory center
26
Q

Indirect cholinomimetics in the CNS can cause:

A
  1. convusions
  2. coma
  3. respiratory arrest
27
Q

How are cholinomimetics used to threat Alzheimer’s Disease?

A

AChE inhibitors slow progression (do not cure)

28
Q

Name 4 AChE inhibitors used to treat Alzheimer’s Dz

A
  1. Tacrine
  2. Donepezil
  3. Galatamine
  4. Rivastigmine
29
Q

What drugs is used to treat smoking cessation? What does it do?

A

Varenicline

A direct nicotnic agonist that decreases cravings and pleasurable effects of cigarettes

30
Q

Describe how ACh acts at the neuromuscular junction

A
  1. ACh released from presynaptic neurons
  2. ACh binds to nicotinic receptors on muscle fiber
  3. This results in depolarization of muscle fiber
  4. Causes contraction of skeletal muscle
31
Q

Contrast the effects of low, medium, and high doses of indirect cholinomimetics at the neuromuscular junction

A

LOW DOSE: prolongs effects of ACh, increasing the strength of muscle contraction

MEDIUM DOSE: may cause muscles to fibrillate - muscles not effective

HIGH DOSE: block depolarization causing muscle paralysis

32
Q

Myasthenia Gravis

A

An autoimmune process of antibodies targeting nicotinic receptors. These antibodies block binding of ACh to receptors

33
Q

What are some symptoms of myasthenia gravis?

A

Ptosis
Difficulty speaking
Weakness

34
Q

What drugs are used to treat Myasthenia Gravis?

A

AChE inhibitors

35
Q

What cholinomimetic is used to reverse neuromuscular paralysis (usually following surgery)

A

Neostigmine (an indirect acting carbamate ester)

36
Q

What do you use to treat an excessive amount of anticholinergic action in the body?

A

AChE inhibitors (physostigmine) because you want to inc. the amount of ACh at receptor sites

37
Q

Jack eats a mushroom of the genus Inocybe (containing muscarinic alkaloids). What kind of cholinomimetic toxicity does Jack have and what can be done to treat him.

A

Toxicity of Direct muscarinic agonists

Tx: Atropine

38
Q

What is the fatal dose of nicotine?

A

40 mg or 1 drop of pure liquid.

2 ciagrettes has this much, but fortunately most gets destroyed by burning

39
Q

Acute nicotine toxicity can cause:

A
  1. CNS stimulation (convusions, resp. arrest, coma)
  2. Skeletal muscle depolarization –> leads to blockage and resp. paralysis
  3. Hypertension and cardiac arrhythmias
40
Q

How do you treat acute nicotine toxicity?

A

Supportive until drug is metabolized within a few hours

41
Q

What causes cholineresterase inhibitor toxicity?

A

Organophosphates and carbamate cholineresterase inhibitors

42
Q

What symptoms are displayed when one has toxicity of cholineresterase inhibitors?

A

Muscarinic excess

43
Q

How do you treat someone with cholineresterase inhibitor toxicity?

A
  1. Monitor V/S
  2. Decontaminate if possible
  3. Antidote w/ parenteral atropine or pralidoxime

Pharmacology (17 decks)

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