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Pharm for midterm > Cholinergics > Flashcards

Cholinergics Flashcards

1
Q

Hemicholinium

A

inhibits choline transport so you wont be able to make Ach

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2
Q

What are the responses mediated by muscarinic receptors when Ach binds?

A

Heart: decreased HR, AV node conduction
Eyes: contraction of sphincter muscle of iris and ciliary muscle
Gi: increase tone, motility and secretion
bladder: relaxed sphincter
secretory glands: increased secretions (sweat, bronchial, salivary)

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3
Q

M1 receptor

A

stomach-increased acid and pepsin secretion
ganglion-stimulation
CNS-neurotransmission

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4
Q

M2 receptor

A

SA node- increase K+ conduction, slow diastolic depolarization, bradycardia
Atria- decreased contractility, conduction velocity, and refractory period
AV node- slows conduction, AV block
Lung: bronchoconstriction, increased secretions
stomach- increased motility
bladder- contract detrusor, relax sphincter
penis- erection

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5
Q

M3 receptor

A

Eyes- meiosis, accommodation

glands- increase secretions

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6
Q

Direct-acting cholinomimetic drugs

A 
Receptor agonists (all of the following):
Choline esters: Ach, bethanecol, carbachol, methacholine

alkaloids: pilocarpine

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7
Q

Indirect-acting cholinomimetic drugs

A 
Cholinesterase inhibitors (all of the following)
Carbamates: physostigmine, neostigmine, pyridostigmine, edrophonium

phosphates: isoflurophate (irreversible)

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8
Q

Nicotinic receptor

A

skeletal muscle-contract
ganglion-stimulation
CNS-neurotransmission

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9
Q

Bethanechol

A

stimulates the atonic bladder in postpartum or postoperative urinary retention
-actions: increases intestinal motility and tone, stimulates detrusor muscle of bladder while trigone and sphincter are relaxed, causing expulsion of urine.
-Sites: smooth muscle of bladder and GI
direct Ach agonist. Poor substrate for AchE so not broken down well.
-unique: used to promote salivation in Sjogren syndrome (an alternative to pilocarpine)

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10
Q

Carbachol (carbamylcholine)

A

Rarely used; sometimes used as miotic for glaucoma.
Action: direct cholinomimetic, weak nicotinic agonist. Can cause release of epinephrine from adrenal medulla by nicotinic actions. Poor substrate for AchE so it has a longer time to work.
DOA: ~1hr
ADR: little to no side effects when used in the eye

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11
Q

Methacholine

A

Used as DIAGNOSTIC (not medicinally). “Methacholine challenge” for bronchial hyperreactivity and asthmatic conditions.

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12
Q

Cholinomimetic natural alkaloids and synthetic analogs

A

Pilocarpine(muscarinic action)
muscarine (acts at muscarinic receptor sites)
arecoline (acts at nicotinic receptors)

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13
Q

Pilocarpine

A

Emergency lowering of intraocular pressure of both narrow and wide-angle glaucoma. Opens canal of Schlemm, decreases pressure through increased drainage of aqueous humor.
Action: rapid miosis/contraction of ciliary muscle.
ADR: CNS effects, profuse sweating, salivation (some systemic absorption through eye)

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14
Q

Atropine

A

Anti-muscarinic. ANTIDOTE for Ach and Ach agonist toxicity.

This is an anticholinergic—muscarinic receptor antagonist.

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15
Q

Major contraindications to use of choline esters

A
  • Asthma (bronchoconstrictor action can precipitate asthma attack)
  • Hyperthyroidism(=A.fib)
  • Coronary insufficiency (hypotension=decreased coronary blood flow)
  • Peptic ulcer disease
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16
Q

Reversible Anticholinesterases

water-soluble.indirect-acting cholinomimetics

A
  • physostigmine
  • neostigmine
  • pyridostigmine
  • edrophonium
  • tacrine, donepezil, rivastigmine, galantamine
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17
Q

Physostigmine

A

Meiosis: used in glaucoma; increases intestinal and bladder motility; reverses CNS and cardiac effects of tricyclic antidepressants; reverses CNS effects of atropine
Action: amplifies effects of Ach by stopping its’ breakdown.
This is a water-soluble indirect-acting cholinomimetic drug.

18
Q

neostigmine
pyridostigmine
edrophonium

A

Used: Myesthenia Gravis, reversal of neuromuscular block. Used in surgery.
Action: amplifies effects of Ach, increases muscle strength.
Water-soluble. reversible.

19
Q

Isoflurophate

Echothiophate

A

Used: glaucoma (not first line of therapy. used if rxn to other drugs). Administered topically, so no systemic effects.
Action: amplifies effects of Ach.
Lipid-soluble=irreversible b/c it crosses the blood-brain barrier.

20
Q

Effects of excessive Ach

DUMBELS mnemonic

A 
D-diarrhea
U-urination
M-meiosis
B-bronchoconstriction
E-excitation (CNS, skeletal muscle)
L-lacrimation
S-sweating, salivarion
21
Q

nicotinic manifestations

M T W t(H) F mneumonic

A 
M-mydriasis, muscle twitching
T-tachycardia
W-weakness
tH- HTN, hyperglycemia
F-fasciculations
22
Q

Pralidoxime

A

choinesterase reactivator that breaks bond between drug and enzyme (ANTIDOTE)
Treatment for poisoning with organophosphate insecticides. Carried by military in case of exposure.

23
Q

Effects of muscarinic blocking drugs

A
  • CNS: amnesia, delirium, drowziness, anti-parkinsons actions, antimotion sickness action
  • eyes: lens accommodation inhibited, mydriasis, reduction in lacrimal secretions
  • bronchodilation
  • GI: relaxation, slowed peristalsis
  • urinary: relaxed bladder wall, urine retention
  • heart: bradycardia (initially from blocking M2 receptor in heart), then tachycardia (from blocking vagus)
  • Glands: secretions decrease
24
Q

Antimuscarinic drugs for CNS and applications

A
  • Benztropine: treat manifestations of Parkinson’s disease

- scopolamine- prevent/reduce motion sickness

25
Q

antimuscarinic drug for eye

A

Atropine- produces mydriasis and cycloplegia

26
Q

antimuscarinic drug for bronchi

A

ipratorium- bronchodilate in asthma

27
Q

antimuscarinic drug for GI

A

methscopolamine- decrease transient motility; used in combo w/ antiulcer drugs

28
Q

antimuscarinic drug for GU

A

oxybutinin- treats transient cystitis and post-op bladder spasms

29
Q

nicotinic antagonists (ganglionic blockers)

A

mecamylamine and trimethaphan
competitive antagonists of Ach at ganglionic nicotinic receptor.
-interfere w/ post-synaptic transmission of Ach
-block action of Ach on nicotinic receptors

30
Q

nicotinic antagonist (neuromuscular blockers)

A
  • -atracurium, cistracurium, mivacurium (eliminated via hydrolysis)
  • -tubocurarine, pancuronium (renal elimination
  • -rocuronium, vecuronium (liver metabolism
  • succinylcholine (hydrolysis by plasma cholinesterase’s)
31
Q

Botulinum (botox)

A
  • toxin inhibits Ach release, thus interferes w/ nerve impulses and causes flaccid paralysis of muscles
  • antagonistic effect b/c Ach never binds
32
Q

M1, M3, and M5 muscarinic receptors are coupled to G-proteins responsible for stimulation of what?

A

Phospholipase C

33
Q

M2, M4 muscarinic receptors are coupled to G-proteins and are responsible for what 2 things?

A

adenyl cyclase inhibition and K+ channel activation

34
Q

What are the 2 locations for nicotinic receptors?

A

At the autonomic ganglia and neuromuscular junction (somatic motor end plates)

35
Q

Responses Mediated by Nicotinic Receptors:

A

Autonomic ganglia: depolarization
Adrenal medulla: secretion of epinephrine (adrenergic effect)
Neuromuscular junction: depolarization of motor end plate

36
Q

How do ganglionic blockers work (for nicotinic receptors)?

A

Interfere with postsynaptic transmission of Ach
Block action of Ach on nicotinic receptors
Different subtypes of nicotinic receptors exist at ganglia and neuromuscular junctions.

37
Q

2 competitive antagonist of Ach at ganglionic nicotinic receptor

A

Trimethaphan and Mecamylamine

38
Q

Depolarizing neuromuscular blocking drug

A

succinylcholine, Decamethonium

Resistant to AChE so (doesn’t get broken down) they persist in the synaptic cleft and continually depolarize the neuromuscular junction end-plate thus action potential cannot be elicited

39
Q

long-duration, non-depolarizing neuromuscular blocking drug

A

tubocurarine

bind to nicotinic cholinergic receptors to induce a competitive blockade of Ach (Affinity without efficacy)

40
Q

short-duration, non-depolarizing neuromuscular blocking drug

A

vecuronium, pancuronium

Pharm for midterm (5 decks)

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