A3 Antagonists

Question 1

Pharmacological antagonism

Answer 1

when drugs counteract each other by binding to the same receptor type

Question 2

what is 1.occupation, 2. activation governed by

Answer 2

1. Occupation: governed by affinity

2. Activaion: governed by efficacy

Question 3

True or false antagonist has higher affinity for receptor than agonist

Answer 3

True - antagonist reduces agonist response

–> however increasing agonist conc will restore response

Question 4

Irreversible competitive antagonism

Answer 4

bond between antagonist & receptor so strong that increasing agonist conc cant displace antagonist
(often due to covalent bonding)
Can produce non-parallel rightward shifts of agonist conc response curves

Question 5

Non competitive antagonism

Answer 5

bind to other site (allosteric) than agonist binding site. Can produce non-parallel rightward shifts of agonist conc response curves

Question 6

What does the Gaddum equation assume

Answer 6

equal responses are produced by equal proportional occupation of receptor population. (quantifies rightward shift of curve)

Question 7

r of 2 means?

Answer 7

Twice as much agonist is required to produce the same response in presence of antagonist
(for Gaddum-Schild equation when r =2 XB = KB)

Question 8

1. What is the most accurate way of determine Kb
2. what would a slope = 1 mean?
3. the higher the pA2 = the higher the what?

Answer 8

1. Schild plot: KB is estimated as point which line crosses the axis.
2. antagonist is competitive
3. The higher the pA2 the higher the potency