Cholinesterase Inhibitors.

Question 1

What are the functions of cholinesterase inhibitors?

Answer 1

It inhibits acetylcholinesterase.

Question 2

What happens when acetylcholinesterase is inhibited?

Answer 2

ACH builds up in the synaptic cleft and this increases cholinergic activity.

Question 3

What are the 2 categories of acetylcholinesterase inhibitors?

Answer 3

Reversible inhibitors.

Irreversible inhibitors.

Question 4

What are some examples of reversible acetylcholinesterase inhibitors?

Answer 4

Physostigmine.

Pyridostigmine.

Neostigmine.

Edrophonium.

Question 5

What are some examples of irreversible acetylcholinesterase inhibitors?

Answer 5

Organophosphate.

Question 6

What are the 2 active sites on ACHE?

Answer 6

An anionic site.

An esteratic site.

Question 7

What does the anionic site of ACHE bind to?

Answer 7

Positively charge molecules such as the nitrogen on ACH.

Question 8

What does the esteratic site of ACHE bind to?

Answer 8

The carboxyl group on ACH.

Question 9

How does ACHE break down ACH?

Answer 9

It combines with water to form acetic acid and choline.

Question 10

What happens to the choline that is formed via the breakdown of ACH by ACHE?

Answer 10

It is recycled.

Question 11

Is the ACHE enzyme re-usable?

Answer 11

Yes.

Question 12

How do reversible cholinesterase inhibitors work?

Answer 12

The bind to the ionic and esteratic sites of ACHE and are then slowly broken down by ACHE.

Question 13

How do organophosphate compounds inhibit ACHE?

Answer 13

They bind to the ionic and esteratic sites of ACHE and cannot be removed.

Question 14

Organophosphate compounds are found in what substances?

Answer 14

Pesticides.

Question 15

What are 4 examples of reversible cholinesterase inhibitors?

Answer 15

Physostigmine.

Neostigmine.

Pyridostigmine.

Edrophonium.

Question 16

Can physostigmine act in the CNS?

Answer 16

Yes, as it can cross the blood brain barrier.

Question 17

Is physostigmine a reversible or irreversible cholinesterase inhibitor?

Answer 17

A reversible cholinesterase inhibitor.

Question 18

What conditions is physostigmine used to treat?

Answer 18

Glaucoma.

It is the antidote for atropine toxicity.

Question 19

Physostigmine can be used as the antidote for what?

Answer 19

Atropine toxicity.

Question 20

How is neostigmine absorbed?

Answer 20

Orally.

Question 21

Does neostigmine affect the CNS?

Answer 21

Yes, but not as much as physostigmine.

Question 22

What receptors will neostigmine bind to?

Answer 22

Nicotinic receptors at the neuromuscular junction.

Question 23

What 2 conditions is neostigmine used to treat?

Answer 23

Myasthenia gravis.

Reverse neuromuscular blockade.

Question 24

Is neostigmine a reversible or irreversible cholinesterase inhibitor?

Answer 24

A reversible cholinesterase inhibitor.

Question 25

Is edrophonium a reversible or irreversible cholinesterase inhibitor?

Answer 25

A reversible cholinesterase inhibitor.

Question 26

How does edrophonium interact with ACHE?

Answer 26

It binds to the ionic site and the esteratic site.

Question 27

Edrophonium will compete with what to bind to ACHE?

Answer 27

ACH.

Question 28

Does edrophonium have a short or long duration of action?

Answer 28

A short duration of action.

Question 29

What conditions is edrophonium used for?

Answer 29

For diagnosis of myasthenia gravis. Anti curare.

Question 30

What is a significant side effect of edrophonium?

Answer 30

Bradycardia.

Question 31

What is the preferred drug for treatment of myasthenia gravis?

Answer 31

Pyridostigmine.

Question 32

What is the pharmacological effect of neostigmine on skeletal muscle?

Answer 32

Stimulation of nicotinic receptors.

Question 33

Will neostigmine be more likely to affect skeletal muscle at high or low doses?

Answer 33

At low doses.

Question 34

What are anticurare agents?

Answer 34

Antagonists to non-depolarising neuromuscular blocking agents.

Question 35

What are common pharmacologic effects of reversible cholinesterase inhibitors?

Answer 35

Ganglionic stimulation. Hypotension, bradycardia, arrhythmia. Bronchoconstriction. Contraction of the urinary bladder.

Question 36

What are the side effects of large doses of physostigmine?

Answer 36

Stimulation and then depression of the CNS.

Question 37

What are the side effects of massive doses of physostigmine?

Answer 37

Convulsions.

Question 38

What are the 6 side effects of neostigmine?

Answer 38

Skeletal muscle weakness. Nausea. Vomiting. Colic. Diarrhoea. Bradycardia.

Question 39

What is the antidote for toxic effects caused by reversible cholinesterase inhibitors?

Answer 39

Atropine.

Question 40

Will organophosphates penetrate the blood brain barrier?

Answer 40

Yes.

Question 41

What are 3 compounds that act as irreversible cholinesterase inhibitors?

Answer 41

Pesticides. Nerve gas. Dichlorvos.

Question 42

What is the mode of action of irreversible cholinesterase inhibitors?

Answer 42

It binds to and irreversibly inhibits ACHE.

Question 43

What are the symptoms of organophosphate poisoning?

Answer 43

Increased salivation. Vomiting. Diarrhoea. Frequent urination. Bradycardia. Hypotension. Muscle twitching/paralysis.

Question 44

What are the 2 antidotes for organophosphate poisoning?

Answer 44

Atropine as it will bind to ACHE and prevent the toxin from binding. Pralidoxime will help re-generate ACHE enzymes that are blocked.

Question 45

How does pralidoxime act as an antidote for organophosphate poisoning?

Answer 45

It removes the organophosphate from the ACHE.

Question 46

How soon should we give pralidoxime to victims of organophosphate poisoning?

Answer 46

As soon as possible.