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Pharmacology - Exam 2 > Cholinergics > Flashcards

Flashcards in Cholinergics Deck (44)
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1
Q

What are the direct-acting Ach agonists?

A
  • Ach (not useful as a drug)
  • carbachol
  • bethanechol
  • nicotine
  • varenicline
2
Q

What are the indirect-acting Ach agonists?

A
  • neostigmine
  • physostigmine
  • doenpezil
  • sarin (no therapeutic value)
3
Q

What chemicals and enzyme synthesize Ach in cholinergic nerve terminals?

A

choline + acetyl-CoA

choline acetyltransferase (ChAT)

4
Q

What enzyme rapidly breaks Ach down in the synaptic cleft?

A

Acetylcholinesterase

5
Q

What are the two major types of cholinergic receptors?

A

nicotinic

muscarinic

6
Q

What kind of Ach receptor are all G-protein-coupled metabotropic receptors?

A

Muscarinic

7
Q

What are the two types of muscarinic receptors and what do they do?

A
  1. Evens (M2 and M4) - inhibition of cAMP production (stimulates smooth muscle) or activation of voltage-gated K+ channels (inhibits smooth muscle)
  2. M1, M3, and M5 - activate IP3, diacylglycerol cascase to increase intracellular Ca2+ (stimulates smooth muscle)
8
Q

What specific muscle do the M2 and M4 cAMP inhibiting receptors act on?

A

contracts GI muscle

9
Q

What specific muscle do the M2 and M4 K+ GTP receptors act on?

A

SA node cells (hyperpolarizes and slows HR)

10
Q

What specific muscle does the M1, M3 and M5 receptors act on?

A

Ciliary muscle - increased Ca2+ contracts

11
Q

Skeletal muscle postsynaptic receptors are what type?

A

Nicotinic

12
Q

Postsynaptic autonomic ganglia and adrenal medulla receptors are what type?

A

nictonic

13
Q

Presynaptic receptors in the CNS are what type?

A

mostly nicotinic

14
Q

Postsynaptic receptors on parasympathetic end organs and sweat glands are what type?

A

muscarinic

15
Q

What type of Ach receptor is on the postsynaptic receptors of the CNS?

A

Mostly muscarinic

16
Q

What is an important effect of direct acting muscarinic agents on small blood vessels?

A

causes release of NO which dilates vessels and decreases BP

17
Q

What are the direct-acting muscarinic agonists?

A
  • carbachol
  • bethanechol
18
Q

what type of drug is carbachol?

A

direct-acting muscarnic agonist

*also a nicotinic agonist at high doses

19
Q

what type of drug is bethanechol?

A

direct-acting muscarinic agonist

20
Q

Which muscarnic agonists are not broken down by Achesterase?

A

carbachol and bethanechol

21
Q

What are the indications for the direct-acting muscarinic agonists?

A
  • paralytic ileus (post-operative)
  • urinary retention
  • carbachol eyedrops in wide (open) angle glaucoma
22
Q

What are the adverse effects of the direct-acting muscarinic agonists?

A
  • hypotension
  • diarrhea
  • vomiting
  • bronchial constriction
  • sweating
23
Q

Who is contraindicated from receiving direct acting muscarinic agonists?

A
  • asthma
  • heart conditions
  • peptic ulcer
  • GI or urinary obstruction
  • hyperthyroidism (a fib)
24
Q

What are the effects of the muscarinic antagonists?

A
  • tachycardia
  • blunted reflexes
  • mydriasis
  • inability to sweat
  • constipation
  • urinary retention
  • GI antispasmodic
  • possible hallucinations
25
Q

What kind of drug is atropine and what does it do?

A

muscarinic antagonist

  • preanesthetic medication (reduce secretions, relax bronchi)
  • antispasmodic
  • antidiarrheal

*crosses the BBB

26
Q

What kind of drug is ipratropium and what does it do?

A

muscarinic antagonist

  • bronchodilation in COPD

*stays in lungs, limited Vd

27
Q

What kind of receptors are nicotinic?

A

excitatory ligand gated ion channels

permeable to Na+ and K+

*Nicotinic neuronal also permable to Ca2+

28
Q

What is the role of postsynaptic nicotinic receptors?

A

produce depolarization and excitation of neurons and skeletal muscle

29
Q

Where does Ach bind to nicotinic receptors?

A

The alpha subunit

30
Q

What is the function of presynaptic nicotinic receptors?

A

enhance release of many other neurotransmitters in the CNS

31
Q

vecuronium is highly specific for which receptor subtype?

A

NM

(Muscular)

32
Q

What drug is a potent nicotinic receptor agonist?

A

nicotine

*uncharged and readily passes into the BBB

33
Q

What does nicotine do in the brain?

A

Binds to presynaptic nicotinic Ach receptors, which causes Ca2+ to enter and excitatory NTs to be released

34
Q

How does nictoine become addictive?

A

increases the release of dopamine in the midbrain reward pathway, particularly in the nucleus accumbens

leads to pleasurable feeling

*same circuit as compulsive gambling

35
Q

What is the midbrain reward circuit for nicotine?

A

alpha 7 Ach presynaptic receptors on glutamate neurons–> ventral tegmental dopaminergic neurons –>dopmaine nucleus accumbens –>prefrontal cortex

Note that nicotine also binds to alpha4beta2 Ach presynaptic receptors in the ventral tegmental and nucleus accumbens to enhance dopamine release

36
Q

What are withdrawal symptoms from nicotine?

A

headache

irritability

inability to concentrate

weight gain

37
Q

What receptors in the brain are double in amount in smokers, leading to tolerance?

A

alpha4 beta 2 nicotinic

38
Q

What are some CNS effects of nicotine in naive users?

A

nausea and emesis

excitation, increased arousal

increased attention

39
Q

What are some CNS effects of nicotine in experienced users?

A

excitation, increased arousal

increased attention

relaxation

addiction

craving

40
Q

What are the peripheral effects of nicotine?

A

increased BP

increased HR

stimulation of all autonomic ganglia and adrenal medulla

GI: increased tone and activity

41
Q

What is a clinical use of nicotine?

A

smoking cessation (nicorette)

42
Q

Is vaping a good alternative to cigarette smoking?

A

Yes and No

fewer carcinogens in vapor

we don’t know the safety of flavors/propylene glycol/glycerin in vaping products

43
Q

What are some of the smoking cessation drugs?

A

nicotine replacement

buproprion (antidepressant)

varenicline (chantix)

44
Q

What is the mechanism of action of varenicline?

A

partial agonist at alpha4 beta2 nicotinic receptors

binds with 30-60% efficacy, competes with nicotine for access to these receptors

BLACK BOX: for neuropsychiatric symptoms, including depression, suicidal ideation