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Pharm (Geisel M2) > Term 1 Pharm - Cholinergic (Ach) > Flashcards

Term 1 Pharm - Cholinergic (Ach) Flashcards

1
Q

What is Acetylcholine (Ach) made of:

A

Acetate + ester bond + choline

Ach = Acetyl CoA + choline

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2
Q

Enzyme that breaks dow ACh

A

acetylcholinesterase

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3
Q

Once Ach is broken down what happens?

A

choline is recycled back into axon terminal and used to make more ACh

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4
Q

All cholinergic receptors are activated by?

A

Ach

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5
Q

What are the two categories of cholinergic receptors and where are they?

A

Subdivided into muscarinic or nicotinic

Muscarinic = Mostly located on parasympathetic effector cells, sweat glands of sympathetic post ganglions, endothelium

Nicotinic = Located in ganglia (Nn) and neuromuscular end plates (Nm)

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6
Q

Where is acetylcholine (ACh) the neurotransmitter?

A
  • All autonomic ganglia
  • Postganglionic termini of parasympathetic fibers (post synaptic)
  • Postganglionic termini of sympathetic-cholinergic fibers (sweat glands) (post synaptic)
  • Adrenal medulla (specialized sympathetic ganglion)
  • Termini of somatic motor nerves to skeletal muscle, neuromuscular junctions (NMJ)/motor end plates
    CNS
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7
Q

Toxic Syndromes with too much cholinergic inhibition:

A

Anti-cholinergic
(Classic example = Atropine)

1) Mad as a hatter: delirium, MOST DANGEROUS TOXICTY IN ADULTS (self harm)
2) Blind as a bat: mydriasis, blurred vision, inhibits ciliary muscle constriction, makes closed angle glaucoma worse
3) Dry as a bone: reduces secretions, saliva, skin, eyes, and bronchial secretions
4) Hot as a hare: elevated body temperature, MOST DANGEROUS IN PEDIATRICS as resistant to usual antipyretics, have to use ice bath
5) Red as a beet: skin flushing
6) Also urinary retention from blocked detrusor, bronchodilation, constipation, tachycardia and hypertension

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8
Q

Toxic Syndromes with too much cholinergic stimulation:

A 
D	diarrhea
U	urination
M	miosis
B	bronchorrhea
B	bradycardia
E	Excitation of skeletal muscle leading to paralysis (nicotinic receptor), Emesis (muscarinic)
L	lacrimation
S	salivation
S	sweating
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9
Q

Non-specific Direct Acting Cholinergic Agonist

A

Carbachol

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10
Q

(3) Muscarinic direct acting cholinergic agonists

A

1) Bethanechol
2) Pilocarpine
3) Methacholine

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11
Q

(3) Nicotinic direct acting cholinergic agonists

A

1) Varenicline
2) Nicotine
3) Succinylcholine

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12
Q

Non-selective muscarinic and nicotinic receptor agonist

Actions: Used as an ocular agent it causes miosis and increases aqueous humor outflow.

Uses: Open angle glaucoma

Toxicity:
Overdose could cause effects similar to nerve gas (DUMBBELSS) but as a topical agent this is unlikely

Other facts: topical, not broken down efficiently by acetylcholinesterase, therefore long duration of activity

A

Carbachol (generic)

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13
Q

Non-selective muscarinic receptor agonist

Actions: Used to increase detrusor muscle tone and GI motility post operatively

Uses: Urinary retention, neurogenic bladder, GERD

Toxicity:
reflex tachycardia (due to vasodilation), bronchoconstriction, increased secretory activity (sweat, GI/respiratory secretions)

Other facts: oral dosing

A

Bethanechol (generic)

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14
Q

Non-selective muscarinic receptor agonist

Actions: muscarinic receptor activation

Indications: glaucoma, acute angle-closure, open angle glaucoma, decreases intraocular pressure and dry mouth/xerostomia, Sjogren syndrome-or head and neck cancer-associated,

Toxicity: reflex tachycardia (due to vasodilation), bronchoconstriction, increased secretory activity (sweat, GI/respiratory secretions)

Other facts: eye drops or oral

A

Pilocarpine (Salagen)

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15
Q

Non-selective muscarinic agonist

Actions: Used to diagnose bronchial hypereactivity (asthma predominantly over COPD). “Methacholine challenge”, inhaled aerosolized methacholine with monitoring of bronchoconstriction

Uses: For diagnosis of asthma only

Other facts:
Inhaled only

A

Methacholine (Provocholine)

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16
Q

Nicotinic cholinergic agonist

Actions: binds to nicotinic receptors; slower action than the nicotine found in cigarettes

Uses: smoking cessation; nicotine withdrawal

Adverse drug reactions: bronchospasm, nicotine dependence transference

Other facts: gum/patch/nasal

A

Nicotine (generic)

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17
Q

Nicotinic receptor partial agonist

Actions: a partial agonist it reduces cravings for and decreases the pleasurable effects of cigarettes by inhibiting the ability of nicotine to stimulate the mesolimbic dopamine system

Uses: smoking cessation;
Adverse drug reactions: nausea, headache, insomnia, abnormal dreams

Other facts: oral

A

Varenicline (Chantix)

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18
Q

Indirect acting cholinomimetic (presynaptic)

Has largely replaced bethanachol for post-surgery gastroparesis and antiemetic

Acts by stimulating presynaptic D2 receptors to trigger ACh release

A

Metoclopramide

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19
Q

Indirect acting cholinomimetic
Cholinesterase inhibitor
Short acting (1)

A

Edrophonium

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20
Q

Indirect acting cholinomimetic
Cholinesterase inhibitor
Intermediate acting (4)

A

1) Neostigmine
2) Pyridostigmine
3) Physostigmine
4) Donepezil, (galantamine, rivastigmine)

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21
Q

Indirect acting cholinomimetic
Cholinesterase inhibitor
Long acting (3)

A

1) Echothiophate
2) Organophosphates (e.g. insecticides: parathion, malathion)
3) Nerve gases (e.g. Sarin, soman)

22
Q

Reversible acetylcholinesterase inhibitor
Indirect cholinergic agonist

Actions: blocks action of acetylcholinesterase

Uses: Used to diagnose myasthenia gravis

Toxicity: cholinergic reaction (DUMBBELS)

Other facts: very short half-life 10-30 mins duration, iv, highly charged does not cross blood brain barrier

A

Edrophonium (Tensilon test)

23
Q

Reversible cholinesterase inhibitor

Actions: increases acetylcholine availability for postsynaptic membrane receptors

Uses: Myasthenia gravis, nondepolarizing neuromuscular blockade reversal (rocuronium and vecuronium), urinary retention

Toxicity: cholinergic reaction (DUMBBELSS)

Other facts: iv/im/sc does NOT enter CNS

A

Neostigmine (Bloxiverz)

24
Q

Reversible cholinesterase inhibitor

Actions: indirectly stimulates both nicotinic and muscarinic acetylcholine receptors

Indications: glaucoma, Alzheimer’s disease, delayed gastric emptying, anticholinergic toxicity with CNS effects e.g. atropine overdose, nondepolarizing neuromuscular blockade reversal

Toxicity: cholinergic reaction (DUMBBELSS)

Other facts: crosses the BBB so not used for myasthenia gravis (uncharged and lipid soluble), iv/im

A

Physostigmine (generic)

25
Q

Reversible cholinesterase inhibitor

Actions: indirectly stimulates both nicotinic and muscarinic acetylcholine receptors

Indications: myasthenia gravis treatment, shorter half-life than neostigmine

Toxicity: cholinergic reaction (DUMBBELS)

Other facts: does not cross blood brain barrier, low oral bioavailability,

A

Pyridostigmine (generic)

26
Q

Reversible cholinesterase inhibitor

Actions: indirectly stimulates both nicotinic and muscarinic acetylcholine receptors

Indications: Alzheimer’s associated dementia

Toxicity: GI upset

Other facts: crosses blood brain barrier, 100% oral bioavailability,

A

Donepezil (Aricept)

Other drugs used for dementia:

  • Rivastigmine (Exelon) reversible cholinesterase inhibitor patch form reduces GI upset
  • Galantamine NN agonist and acetylcholinesterase inhibitor
27
Q

IRreversible cholinesterase inhibitor

Actions: binds irreversibly to acetylcholine binding site on cholinesterases (cholinesterase inhibitor)

Indications: glaucoma topical

Toxicity: lacrimation, stinging

Other facts: topical only, very long half-life

A

Echothiophate (Phospholine Iodide)

28
Q

the ONLY Indirect Cholinergic Antagonist = Anticholinergic (muscarinic and nicotinic)

A

Botulism toxin (BOTOX)

  • Botulinum toxin type A, Produced from Clostridium botulinus → botulism
  • Most toxic molecule known, large molecule
  • Inhibits release of ACh from synaptic vesicles
  • Blocks docking of vesicles and neurotransmitter release
29
Q

Anticholinergic = Parasypatholytic
Muscarinic Receptor Antagonists
(prototype)

A

Atropine

30
Q

Clinical uses of muscarinic anticholinergics

A
  • Motion sickness
  • Irritable bowel syndrome
  • Urinary urgency and bladder spasm
  • Ophthalmology (dilating pupil)
  • Parkinson’s disease
  • Bronchodilation in asthma and COPD
  • Cholinergic poisoning
31
Q

Muscarinic anticholinergic for Motion sickness:

A

Scopolamine

32
Q

Muscarinic anticholinergic for Irritable bowel syndrome

A

Dicyclomine

33
Q

Muscarinic anticholinergic for Urinary urgency and bladder spasms

A

Oxybutynin and Glycopyrrolate

34
Q

Muscarinic anticholinergic for Ophthalmology, dilating pupil

A

Tropicamide (shorter duration of action than atropine)

35
Q

Muscarinic anticholinergic for Parkinson’s disease

A

Benztropine

36
Q

Muscarinic anticholinergic for Bronchodilation in asthma and COPD

A

Ipratropium and tiotropium

37
Q

Muscarinic anticholinergic for Cholinergic poisoning

A

Atropine and 2-PAM

38
Q

Non-selective muscarinic receptor blocker

Actions: prevents action of acetylcholine, lowers activity of all muscles and glands regulated by the parasympathetic nervous system

Uses: organophosphate poisoning (insecticide, nerve gas –given with Pralidoxime/2-PAM), optically for pupil dilation, bradycardia, to reduce secretions

Toxicity: (Toxic Syndromes with too much cholinergic inhibition)

Other facts: SC; IM; IV; INJ lipid soluble so crosses BBB for when toxins have also crossed BBB

A

Atropine

39
Q

Reactivates cholinesterase

Actions: binds to organophosphate inactivated acetylcholinesterase and accelerates reactivation

Uses: cholinesterase inhibitor overdose, organophosphate insecticide poisoning, organophosphate nerve agent poisoning

Toxicity: when used with atropine, as it usually is, atropine toxicity is enhanced (Toxic Syndromes with too much cholinergic inhibition)

Other facts: iv/im only, useful if administered soon after exposure to toxin, military has stockpiles of auto-injectors in case of nerve gas use

A

Pralidoxime (2-PAM)

40
Q

Muscarinic (some M1 specificity) and histamine receptor blocker

Actions: centrally acting anticholinergic/antihistamine agent

Uses: parkinsonism, dystonia, extrapyrimidal symptoms

Toxicity: (similar to atropine)

Other facts: IM IV

A

Benztropine (Cogentin)

41
Q

Non-selective muscarinic receptor blocker

Actions: Some indication of M1 receptor specificity, anti-emetic (vomit)

Uses: motion sickness, to dilate eye

Toxicity: (similar to atropine)

Other facts: transdermal, can cross BBB,

A

Scopolamine (Scopoderm)

42
Q

Muscarinic receptor blocker, anticholinergic

Actions: inhaled bronchodilator (M3 receptors in lung)

Uses: asthma and COPD.

Toxicity: rare and only through overdosing, dry mouth and sedation, other atropine-like anticholinergic effects

Other facts: inhaled, bad taste, slower onset than beta-2 agonists (albuterol, etc.) can be combined with albuterol in 1 inhaler; duration 6-8 hrs.;

A

Ipratropium bromide (Atrovent HFA)

Tiotropium (Spiriva) longer acting used more for COPD.

43
Q

Non-selective muscarinic receptor blocker

Actions: relaxes smooth muscle, inhibits bradykinin- and histamine-induced bowel spasms

Uses: irritable bowel syndrome

Toxicity: similar to atropine, dry mouth, nausea, most common and at higher doses deliriant effects

Other facts: oral

A

Dicyclomine (Bentyl)

44
Q

What is the ONE depolarizing NM antagonist (NMJ blocker)?

Explain how it works?

A

Succinylcholine

  • Initial activation → subsequent deactivation
  • Initial depolarization leads to muscle fasciculations
  • Prolonged receptor occupancy with ACh leads to receptor phosphorylation and inactivation (termed: depolarization-desensitization blockade)
  • Result is a paradoxical flaccid paralysis which cannot be practically reversed; have to wait until agonist is cleared
  • Over activation of the nicotinic receptor produces a net K+ efflux from muscle → hyperkalemia
45
Q

Nicotinic NMJ blocker (depolarizing), Neuromuscular Blockers, nicotinic acetylcholine receptor agonist

Actions: production of complete skeletal muscle relaxation, flaccid paralysis, Initial stimulation of nicotinic receptors is not terminated and the motor endplate depolarizes, which causes flaccid skeletal muscle paralysis; is not broken down by acetylcholinesterases

Uses: short-term muscle relaxation in anesthesia and intensive care, intubation

Toxicity: BLACK BOX rare acute rhabdomyolysis w/ hyperkalemia followed by ventricular dysrhythmias, cardiac arrest, and death after admin. to apparently healthy children subsequently found to have undiagnosed skeletal muscle myopathy, most frequently Duchene muscular dystrophy;

Other facts: IV, short acting , ONLY NMJ depolarizing blocker in clinical use; do NOT give to patients lacking ChE (causes prolonged paralysis), no reversal agent

A

Succinylcholine (Anectine)

46
Q

Nicotinic NMJ blocker (non-depolarizing), Reversible competitive inhibition

*Prototypic nondepolarizing blocker

Actions: directly blocks receptors on nicotinic end plate, thereby causing flaccid skeletal muscle paralysis

Uses: production of complete skeletal muscle relaxation (surgery, etc), first of its class now replaced by safer alternatives (cisatracurium and rocuronium)

Toxicity: respiratory failure, produces paralysis in fully conscious patients, tachycardia, hypertension, histamine release, ganglionic and muscarinic side effects

Other facts; duration of action 30-60 minutes, neostigmine will reverse action, Quaternary amine so minimal CNS effects

A

d-Tubocurarine (curare)

  • 15th century Europeans met Amazonian Indians hunted with arrows dipped in curare extract
  • can eat prey b/c not orally bioavailable
  • Produces paralysis in fully conscious patients
  • Never give such a drug to an unanesthetized patient
  • Never let a patient emerge from anesthesia before reversing the paralysis
47
Q

Nicotinic NMJ blocker (non-depolarizing), Reversible competitive inhibition, aminosteroid

Uses: directly blocks receptors on nicotinic end plate, thereby causing flaccid skeletal muscle paralysis, used in drug cocktail for executions

Uses: production of complete skeletal muscle relaxation (surgery, etc.),

Toxicity: BLACK BOX admin. by adequately trained individuals familiar w/ actions, characteristics, and hazards. respiratory failure, produces paralysis in fully conscious patients, tachycardia, hypertension, histamine release, ganglionic and muscarinic side effects

Other facts; duration of action 30-60 minutes, neostigmine will reverse action, hepatic impairment: caution advised

A

Vecuronium (generic)

48
Q

Nicotinic NMJ blocker (non-depolarizing), Reversible competitive inhibition, Benzoisoquinolinium analogue

Actions: antagonizes motor endplate acetylcholine receptors

Uses: production of complete skeletal muscle relaxation (surgery, etc.), intubation

Toxicity: respiratory failure, produces paralysis in fully conscious patients, tachycardia, hypertension, histamine release, ganglionic and muscarinic side effects

Other facts; duration of action 30-60 minutes, neostigmine will reverse action

A

Cisatracurium (Nimbex)

49
Q

For nondepolarizing nicotinic blockers (competitive inhibitors) you reverse with:

A

Neostygmine (do not need CNS penetration)

50
Q

How do you reverse depolarizing nicotinic blockers (succinylcholine)?

A

There is no reversal agent only time will allow breakdown of succinylcholine by cholinesterases

51
Q

Nicotinic ganglionic blocker (non-depolarizing), Reversible competitive inhibition,

Actions: blocks both the sympathetic nervous system and the parasympathetic nervous system. It acts as a non-depolarizing competitive antagonist at the nicotinic acetylcholine receptor

Uses: rarely used but sometimes for hypertensive crisis or in dissecting an aortic aneurism

Toxicity: Very toxic and only used in emergency situations, Orthostatic hypotension, urinary retention, constipation, impaired accommodation of lens of the eye
Other facts; short-acting, IV, does not cross BBB

A

Trimetaphan (Arfonad)

52
Q

Bacterial exotoxin, inhibitor of ACh release from nerve terminals

Actions: causes botulism; interferes with docking proteins on the interior of the nerve membrane (vesicles containing ACh cannot dock properly and therefore cannot release Ach)

Uses: remove facial wrinkles and prevent hyperhydrosis (BoTox), migraines

Toxicity: BLACK BOX Distant Spread of Toxin Effect can produce sx consistent w/ botulinum toxin: asthenia, generalized muscle weakness, diplopia, blurred vision, ptosis, dysphagia, dysphonia, dysarthria, urinary incontinence, and breathing difficulties; swallowing and breathing difficulties may be life-threatening and deaths reported; sx occur hours to weeks after injection;

Other facts: Local injections to prevent systemic effects

A

Botulinum toxin (BoTox)

Pharm (Geisel M2) (15 decks)

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