Cholinomimetics

Question 1

Which receptors do cholinomimetics bind to?

Answer 1

Muscarinic or nicotinic receptors

Question 2

Name the direct acting cholinomimetics

Answer 2

Ach
Bethanecol
Carbachol
Methacholine

Cevimeline
Varenicline

Pilocarpine 
Lobeline 
Arecoline 
Nicotine 
Muscarin

Question 3

Name the quaternary cholinomimetics

Answer 3

Ach
Bethanechol 
Carbachol
Methacholine 
Muscarin

Question 4

Name the tertiary direct acting cholinomimetics

Answer 4

Pilocarpine
Lobeline
Arecoline
Nicotine

Question 5

What are the clinical uses of Bethanechol?

Answer 5

Non-obstructive GIT dysmotility e.g., Ileus, gastric atony, post op abdominal distension
Urinary retention

Question 6

What are the clinical uses of Carbachol?

Answer 6

Glaucoma (during surgery)

Question 7

What are the clinical uses of Acetylcholine?

Answer 7

No clinical use due to the half life.

Exception: when short myosin is needed e.g., cataract surgery

Question 8

What is the action of Methacholine?

Answer 8

Bronchoconstriction

Question 9

What is the clinical use of Methacholine?

Answer 9

Methacholine challenge for the diagnosis of pulmonary function

Question 10

What are the side effects of Bethanechol?

Answer 10

Sweating
Salivation 
Flushing 
Decreased BP 
Nausea
Abdominal pain 
Diarrhoea
Bronchospasm

Question 11

What is the antidote for bethanecol toxicity?

Answer 11

Atropine sulfate

Question 12

What is the clinical use of Cevimeline?

Answer 12

Sjogren syndrome

Question 13

What is the clinical use of Varenicline?

Answer 13

Cessation of smoking as it is a partial nicotinic agonist

Question 14

Which cholinomimetic is a partial nicotinic agonist?

Answer 14

Varenicline

Question 15

What are the clinical uses of Pilocarpine?

Answer 15

Glaucoma
Xerostomia
Sjogren syndrome
Salivary gland hypofunction due to radiotherapy of head and neck

Question 16

How is pilocarpine administered in the treatment of glaucoma?

Answer 16

Topically

Question 17

What is the mechanism of action of Pilocarpine in the treatment of glaucoma?

Answer 17

Pilocarpine causes myosin and ciliary contraction which decreases aqueous humour production which decreases IOP.

Question 18

What are the side effects of pilocarpine?

Answer 18

Cyclopegia
Night blindness
Brow ache

Question 19

What is the antidote for pilocarpine toxicity?

Answer 19

Parenteral atropine

Question 20

What are the alkaloids?

Answer 20

Pilocarpine
Lobeline
Arecoline
Arecoline
Nicotine
Muscarine

Question 21

What is the mechanism of action of Pilocarpine?

Answer 21

increased salivation

Question 22

What is the mechanism of action of Arecoline and Nicotine?

Answer 22

inhibits reward effect of nicotine in the limbic system

Question 23

Is muscarine a quaternary or tertiary amine?

Answer 23

Quaternary

Question 24

Can muscarine enter the CNS?

Why?

Answer 24

No

Quaternary amine

Question 25

What are the indirect acting cholinomimetics?

Answer 25

Ach esterase inhibitors

Question 26

What are the reversible AChEIs?

Answer 26

Edrophonium | Carbamates

Question 27

Is Edrophonium competitive or non-competitive?

Answer 27

Competitive

Question 28

Are carbamates competitive or non-competitive?

Answer 28

Non-competitive

Question 29

What are the characteristics of Edrophonium?

Answer 29

Short acting Alcohol Quaternary amine

Question 30

What is the duration of action of Edrophonium?

Answer 30

5-15 mins (injection)

Question 31

What is the clinical indication of Edrophonium?

Answer 31

Tensilon test

Question 32

What are the characteristics of Physostigmine?

Answer 32

Tertiary amine | Carbamate

Question 33

Can physostigmine enter the CNS? Why

Answer 33

Yes Tertiary amine

Question 34

What is the duration of action of Physostigmine?

Answer 34

0.5-2 hours

Question 35

What are the clinical uses of Physostigmine?

Answer 35

Glaucoma | Antidote in atropine overdose

Question 36

What are the characteristics of Rivastigmine?

Answer 36

Tertiary amine | Carbamate

Question 37

Can rivastigmine enter the CNS? Why?

Answer 37

Yes tertiary amine

Question 38

What is the clinical indication of Rivastigmine?

Answer 38

Alzheimer

Question 39

What is the duration of action of Neostigmine and Distigmine?

Answer 39

0.5h-2h

Question 40

What are the clinical indications of Neostigmine, Distigmine?

Answer 40

Ileus Urinary retention MG Reversal of non-depolarising Nm blockers

Question 41

What are the characteristics of Neostigmine and Distigmine?

Answer 41

Quaternary amins | Carbonate

Question 42

Can Neostigmine, Distigmine, Pyridostigmine, Ambenonium and Demecarium enter the CNS? Why?

Answer 42

No Quatenary amine

Question 43

What is the duration of action of Pyridostigmine?

Answer 43

3-6h

Question 44

What is the duration of action of Ambenonium?

Answer 44

4-8h

Question 45

What is the duration of action of Demecarium?

Answer 45

4-6h

Question 46

What is the clinical indication of Pyridostigmine?

Answer 46

- MG (chronic management) | - Prevention of nerve gas

Question 47

What is the clinical indication of Ambenonium?

Answer 47

MG (chronic management)

Question 48

What is the clinical indication of Demecarium?

Answer 48

Glaucoma

Question 49

What are the characteristics of Doneperzile and Tacrine?

Answer 49

Lipid soluble (CNS entry)

Question 50

What are the clinical indications of Doneperzile and Tacrine?

Answer 50

Alzheimers disease

Question 51

What are the clinical indications of Organophosphates?

Answer 51

Glaucoma

Question 52

What is the duration of action of organophosphates?

Answer 52

100 hours

Question 53

What are the characteristics of organophosphates?

Answer 53

Lipid soluble | Irreversible inhibitors

Question 54

What is the antidote given in reversible AChE inhibitors?

Answer 54

Atropine

Question 55

What are the symptoms of acute toxicity with cholinomimetics? (Muscarinic effects)

Answer 55

``` Diarrhea Urination Miosis Bradycardia Bronchoconstriction Lacrimation Salivation Sweating CNS stimulation ```

Question 56

What are the symptoms of acute toxicity with cholinomimetics? (Nicotinic effects)

Answer 56

Skeletal muscle excitation followed by paralysis (cholinergic crisis) - this is irreversible CNS stimulation

Question 57

What are the symptoms of chronic toxicity with cholimomimetics?

Answer 57

Peripheral neuropathy causing muscle weakness and sensory loss (Like MS) Demyelination not due to AChE inhibition

Question 58

Why does demyelination due to chronic toxicity of cholinomimetics occur?

Answer 58

AChE are very lipid soluble so they can go into the myeline sheath, bind to happen and then lead town immune response