Cholinergic drugs

Question 1

Cholinomimetics

Answer 1

Mimic action of ACh
a) Direct (receptor agonists)
b) Indirect (AchE inhibitors)

Question 2

Cholinergic antagonists

Answer 2

Reduce acton of ACh
a) antimuscarinic
b) antinicotinic

Question 3

Direct acting agonist and which receptors (M/N)
-Acetylcholine-

Answer 3

AChE susceptible
M: Agonist
N: Agonist

Question 4

Director acting agonists

Answer 4

-Acetylcholine,
-Bethanechol
-Muscarine
-Pilocarpine
-Nicotine

Question 5

Direct acting agonist and which receptors (M/N)
-Bethanechol-

Answer 5

Not AChE susceptible
M: Agonist
N: No activity

Question 6

Direct acting agonist and which receptors (M/N)
-Muscarine-

Answer 6

Not AChE susceptible
M: Agonist
N: No activity

Question 7

Direct acting agonist and which receptors (M/N)
-Pilocarpine-

Answer 7

Not AChE susceptible
M: Agonist
N: No activity

Question 8

Direct acting agonist and which receptors (M/N)
-Nicotine-

Answer 8

Not AChE susceptible
M: No activity
N: Agonist

Question 9

Indirect acting agonist (AChE inhibitors)

Answer 9

Physostigmine: intermediate-acting
Echothiophate: long-acting

Question 10

Antagonists

Answer 10

Atropine: M-
Trimethaphan: NN-
D-tubocurarine (NM-)

Question 11

Direct receptor agonists: Esters of Choline

Answer 11

Not absorbed/distributed well
a) Acetylcholine
b) Bethanechol

Question 12

Direct receptor agonists:
Alkaloids

Answer 12

Absorbed and distributed well, even in CNS
a) Muscarine
b) Nicotine
c) Pilocarpine

Question 13

True of fasle: Most cholinergic receptor agonists used clinically
are receptor sub-type selective

Answer 13

False: They are not receptor sub-type selective

Question 14

Muscarinic receptor activation activates:

Answer 14

• responses same as PSNS activation
• sweat glands
• endothelial-derived relaxation of blood vessels

Question 15

Nicotinic receptor activation activates:

Answer 15

• activates PSNS and SNS
• skeletal muscle contraction
  (nicotine: initially stimulates then blocks)

Question 16

What effect would pilocarpine have in the eye?

Question 17

If pilocaprine gets into the systemic circulation, what effect will it have in the heart

Question 18

If pilocaprine gets into the systemic circulation, what effect will it have in the blood vessels

Question 19

If pilocaprine gets into the systemic circulation, what effect will it have in the bronchi

Question 20

Nicotine activates which nervous response system at ganglia

Answer 20

Both PSNS and SNS (NN)

Question 21

What does nicotine activation of PSNS and SNS (NN) at ganglia cause

Answer 21

Increase release of ACh and NE in tissues

Question 22

When both PSNS and SNS systems are activated, response from which is observed

Answer 22

PSNS - it is dominant

Question 23

SNS response in blood vessels: which receptors cause what

Answer 23

a1: vasoconstriction (organs and skin)
B2: vasodilation (sk. muscle)

Question 24

Indirect acting choinomimetics: hydrolysis of ACh

Answer 24

ACh –> binds to active site of cholinesterase –> free choline + acetylated enzyme –> +H2O (hydration) –> acetate & choline

Question 25

How is effect of ACh amplified (hydrolysis of ACh)

Answer 25

Inhibitors bind to AChE - reduce ACh hydrolysis = increase local ACh

Question 26

Reversible inhibitors and how

Answer 26

-Carbamate esters: (physostigmine)
-Covalent bond between drug and AChE somewhat resistant to hydration (step 2 of hydrolysis) t ½ =
30 min – 6 h
-Poor absorption and distribution (except physostigmine)

Question 27

Irreversible inhibitors

Answer 27

-Organophosphates: (echothiophate)
-Covalent bond between drug and AChE
phosphate stabilizes bond
t ½ = days to weeks
-Absorbed and distributed well (even in CNS)

Question 28

Amplification of endogenous ACh causes increased ACh at…

Answer 28

-at PSNS and SNS ganglia
- tissues innervated by autonomic ACh-releasing
neurons
-at skeletal muscle
-in CNS