Cholinergics and Anticholinergics Flashcards

1
Q

A direct anticholinergic drug used for the treatment of chronic obstructive pulmonary disease (COPD) and sometimes as an adjunct in the treatment of asthma.

A

Ipratropium bromide: a muscarinic antagonist

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2
Q

In certain genetically susceptible patients, succinylcholine can cause…

A

Apnea

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3
Q

A drug was given to cause surgical paralysis. After surgery, the paralysis was reversed with neostigmine. The drug could have been…

A

Pancuronium or any other non-depolarizing neuromuscular blocking agent (NMBA).

These drugs are direct competitive antagonists at the neuromuscular nicotinic receptors. Increasing the availability of ACh with an AChE inhibitor, such as neostigmine, competes with the antagonism.

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4
Q

Minutes after the initial transient activation that can cause fasciculations and depolarising block, succinylcholine still causes flaccid paralysis. What is the reason for this flaccid paralysis?

A

Secondary non-depolarising block due to desensitization of nicotinic receptors.

For depolarizing NMBAs, this is referred to as Phase II of the block to avoid confusion with non-depolarizing NMBAs (e.g., pancuronium).

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5
Q

Nicotine depolarizes cells opening and inactivating Na+ channels, preventing the firing of action potentials. What is this called?

A

Depolarizing block

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6
Q

List at least THREE non-cosmetic clinical uses for botulinum toxin.

A

Treatment of:
Cervical dystonia
Blepharospasm (excessive blinking)
Strabismus (squints)
Migraine and other headache disorders
Upper limb spasticity

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7
Q

Name at least TWO examples of drugs that increase acetylcholine availability at neuromuscular junctions?

A

Neostigmine, physostigmine, pyridostigmine, donepezil or any other acetylcholine esterase (AChE) inhibitors.

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8
Q

Explain the mechanism of action of botulinum toxin.

A

When injected into skeletal muscle, botulinum toxin acts as an indirect anticholinergic by inhibiting the vesicular exocytosis of acetylcholine (ACh) at synaptic terminals.

It works by cleaving the SNARE proteins required for the capture/docking of synaptic vesicles at the presynaptic membrane.

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9
Q

Can surgical paralysis with succinylcholine be reversed by the administration of an acetylcholine esterase (AChE) inhibitor?

A

No. Succinylcholine is a depolarizing NMBA. It is a potent agonist at neuromuscular junction nicotinic receptors causing depolarising block and receptor desensitization. The addition of an AChE inhibitor will increase the availability of the endogenous agonist acetylcholine and so will not reverse succinylcholine-induced surgical paralysis.

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10
Q

Succinylcholine is an indirect anticholinergic agent clinically used for…

A

Surgical paralysis

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11
Q

To which class of cholinergic or anticholinergic drugs does botulinum toxin injected into skeletal muscle belong?

A

Botulinum toxin is an indirect anticholinergic drug. It works by inhibiting vesicular exocytosis of acetylcholine.

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12
Q

Why does pancuronium sometimes cause increases in heart rate as an adverse effect?

A

Muscarinic receptor antagonism

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13
Q

Why does pancuronium sometimes cause flushing, oedema and hypotension at high doses?

A

Histamine release

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14
Q

List TWO important characteristics/properties of drugs selected to be nondepolarising neuromuscular blocking agents.

A

Low lipid solubility: do not penetrate BBB.
Small volume of distribution (Vd):

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15
Q

By what route are MOST non-depolarizing neuromuscular blocking agents (NMBAs) excreted?

A

Non-depolarizing NMBAs, such as pancuronium, are primarily excreted unchanged in the urine.

Exceptions are rocuronium and vecuronium and their metabolites which are found mainly in bile.

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16
Q

By what route are non-depolarizing neuromuscular blocking agents (NMBAs) administered?

A

IV

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17
Q

Pancuronium is an example of an intermediate-acting non-depolarizing neuromuscular blocking agents (NMBA). How fast a duration of action is considered intermediate for a non-depolarizing NMBA?

A

Approximately 2-5 min. All NMBAs have short durations of action due to a small volume of distribution and rapid excretion. This is essential to allow titration of the level of paralysis during surgery.

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18
Q

What is the clinical use of non-depolarising neuromuscular blocking agents (NMBAs)?

A

To paralyse skeletal muscle for surgical paralysis.

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19
Q

List at least TWO non-depolarising neuromuscular blocking agents (NMBAs) ranked from longest-acting to shortest-acting

A

Non-depolarizing NMBAs from longest-acting to shortest-acting: Tubocurarine (2-13 min) > Pancuronium/Atracurium (2-5 min) > Rocuronium (0.5-3 min).

Note that tubocurarine is now rarely used for surgical paralysis as its duration action is too long to allow fine titration of the depth of paralysis. However, it is still sometimes used to provide temporary muscle paralysis to allow stabilisation of the injured neck or joints.

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20
Q

What are the blanks in the following sentence? “Parasympathetic activation of ___ stimulates secretions in most tissues but gastric acid secretion is due to ___.”

A

M3 receptors
M1 receptors

Parasympathetic activation of _M3 receptors__ stimulates secretions in most tissues but gastric acid secretion is due to _M1 receptors__

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21
Q

What are the blanks in the following sentence? “Patients with organophosphate poisoning present with bradycardia due to
________ of cardiac ____ receptors.”

A

Activation
M2

Patients with organophosphate poisoning present with bradycardia due to _activation__ of cardiac _M2__ receptors.

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22
Q

In organophosphate poisoning, which occurs last (a) twitching/fasciculations of skeletal muscle, (b) rigid paralysis of skeletal muscle, or (b) flaccid paralysis of skeletal muscle?

A

Flaccid paralysis of skeletal muscle.

Organophosphate poisoning inhibits acetylcholine esterase resulting in increased availability of acetylcholine at the neuromuscular junctions. This first causes increased activity of muscle resulting in twitching and sometimes transiently rigid paralysis. However, continued excess of acetylcholine progresses to causing depolarizing and desensitizing block resulting in flaccid paralysis.

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23
Q

List at least FOUR parasympathomimetic symptoms of organophosphate poisoning.

A

Lacrimation
Blurred distant vision
Miosis resulting in darkening of vision
Salivation
Fluid in airways
Bronchoconstriction resulting in wheezing
Diarrhoea due to increased GIT motility and secretions
Urination

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24
Q

What are the blanks in the following sentence? “Pralidoxime is effective in treatment of malathion poisoning because it has a higher affinity for _____ than _____.”

A

Phosphate
AChE

Pralidoxime is effective in treatment of malathion poisoning because it has a higher affinity for _phosphate__ than _AChE__

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25
Q

Pralidoxime is a/an

A

Cholinesterase regenerator used as an antidote to poisoning with organophosphate pesticides and chemicals

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26
Q

Why are organophosphates are described as suicide inhibitors of AChE?

A

Because they donate their phosphate to AChE and so are destroyed in the process of inhibiting AChE

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27
Q

List at least TWO anticholinesterases ranked from longer-acting to shorter-acting

A

AChE inhibitors ranked from longer-acting to shorter-acting: Sarin > Malathion ~ Pyridostigmine > Neostigmine > Physostigmine > Edrophonium

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28
Q

The major clinical use of edrophonium is…

A

Diagnosis of myasthenia gravis

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29
Q

Edrophonium is used for diagnosis not treatment of myasthenia gravis because it…

A

Has a very short half-life

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30
Q

Name an example of an organophosphate insecticide

A

Malathion, parathion

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31
Q

Name an example of an indirect anticholinergic ganglionic blocker

A

High dose nicotine

32
Q

OXYBUTYNIN, a cholinergic antagonist, is CONTRAINDICATED in patients with…

A

Pyloric obstruction, retentive bladder, narrow-angle glaucoma

33
Q

Oxybutynin reduces gastric acid production due to

A

M1 antagonism

34
Q

The sedative effect of ipratropium bromide is likely due to

A

CNS effects of
bromide

35
Q

SCOPOLAMINE is a muscarinic antagonist used as an adjunct for anaesthesia. It is CONTRAINDICATED for patients with

A

Narrow-angle glaucoma

36
Q

An elderly patient experiences motion sickness and is prescribed scopolamine. Likely adverse effects could include…

A

Dry mouth, urinary retention, amnesia, constipation, drowsiness

37
Q

Name a muscarinic cholinergic antagonist used to treat motion sickness.

A

Scopolamine

38
Q

BENZATROPINE, a muscarinic antagonist used to treat symptoms of Parkinson’s disease, is contraindicated in

A

Narrow-angle glaucoma

39
Q

A patient with Parkinson’s disease is prescribed benzatropine. Likely adverse effects could include…

A

Dry mouth, urinary retention, amnesia, constipation, drowsiness

40
Q

Parkinsonism caused by antipsychotic drugs can be reduced by a…

A

Muscarinic antagonist

41
Q

Benzatropine used for the treatment of Parkinson’s disease is a tertiary amine. A TERTIARY AMINE is selected because it…

A

Cross the BBB well

42
Q

Name a cholinergic antagonist used for the treament of Parkinson’s disease

A

Benzatropine

43
Q

Ipratropium is a quaternary amine. Why is a quaternary amine selected for the treatment of asthma?

A

Limited systemic absorption

44
Q

Tertiary amines such as oxybutynin can cross the BBB. So why is oxybutynin used for urinary incontinence?

A

Although compared to a quaternary amine structure, the tertiary amine structure of oxybutynin increases the risk of the drug crossing the BBB, it also improves the GI absorption of the drug.

45
Q

Which of the following muscarinic antagonists is MOST likely to cause CONFUSION in an elderly patient: ipratropium prescribed for asthma or scopolamine prescribed for motion sickness?

A

Scopolamine

46
Q

Scopolamine (Hyoscine) can cause dry mouth by blocking which receptors in the salivary glands?

A

M3

47
Q

Atropine can increase heart rate by blocking which receptors in the heart?

A

M2

48
Q

What is the cardiovascular effect of HIGH DOSE atropine?

A

Tachycardia

49
Q

List at least THREE examples of DIRECT ANTICHOLINERGICS that are also PARASYMPATHOLYTICS.

A

Atropine, Benzatropine, Ipratropium, Oxybutynin, Scopolamine

50
Q

A patient with Alzheimer’s disease is prescribed donepezil. Likely adverse effects could include…

A

Nausea, vomiting, diarrhoea, frequent urination

51
Q

An indirect cholinergic agonist used to treat cognitive symptoms of Alzheimer’s disease

A

Donepezil

52
Q

The major clinical use of NICOTINE is…

A

Smoking cessation

53
Q

Drug that can be simultaneously BOTH sympathomimetic and
parasympathomimetic

A

Nicotine

54
Q

Cardiovascular effect of LOW DOSE nicotine?

A

Tachycardia

55
Q

What is the effect of atropine on vision?

A

Impairment of accommodation resulting in blurring of near vision. Mydriasis resulting in sensitivity to bright light. Dry eyes due to inhibition of lacrimation.

56
Q

MUSCARINIC AGONISTS accommodate the lens of the eye for…

A

Near vision

57
Q

A patient prescribed PILOCARPINE eye drops for glaucoma might experience…

A

Darkening of vision due to miosis
Burring of distant vision
Increased lacrimation (tearing)

58
Q

A patient with urinary retention is prescribed BETHANECHOL. Common adverse effects might include…

A

Nausea, vomiting, diarrhoea

59
Q

What is the effect of MUSCARINIC AGONISTS on the gastrointestinal system?

A

Increased motility and secretions, which can result in diarrhoea

60
Q

What is the MOST COMMON adverse effects of cholinergic agonist that cross the blood-brain barrier (BBB)?

A

Nausea

61
Q

What is the effect of parasympatholytics on the pupil of the eye?

A

Mydriasis (dilation of the pupil)

62
Q

Name a DIRECT MUSCARINIC AGONIST used for the treatment of XEROSTOMIA

A

Pilocarpine

63
Q

Pilocarpine is contraindicated in patients with…

A

Peptic ulcer, asthma

64
Q

Common adverse effects of PILOCARPINE, a muscarinic agonist used to treat xerostomia, include…

A

Sweating, nausea, diarrhoea

65
Q

The major muscarinic receptor subtype CONSTRICTING THE PUPIL of the EYE is…

A

M3

66
Q

The major muscarinic receptor subtype in the HEART is…

A

M2

67
Q

The major muscarinic receptor subtype in the LUNGS is…

A

M3

68
Q

Benzatropine would be used with CAUTION in patients with…

A

Alzheimer’s disease, glaucoma

69
Q

Cardiovascular effect of low dose atropine?

A

Bradycardia

70
Q

A drug for the treatment of dry mouth

A

Pilocarpine

71
Q

Muscarinic ANTAGONISTS are CONTRAINDICATED in patients with…

A

Narrow-angle glaucoma

72
Q

Muscarinic cholinergic receptors on eccrine sweat glands are targets of axonal projections that are

A

Sympathetic & cholinergic

73
Q

Effect of activation of the parasympathetic nervous system on the airways?

A

Bronchoconstriction, increased bronchosecretions

74
Q

The major muscarinic receptor subtype increasing SALIVATION is…

A

M3

75
Q

A muscarinic cholinergic agonist for the treatment of both open-angle and closed-angle GLAUCOMA…

A

Pilocarpine

76
Q

Pilocarpine would be used with CAUTION in patients with…

A

Asthma, peptic ulcer

77
Q

Effect of parasympathomimetic drugs on salivary glands?

A

Increased salivation