Lecture 3 - How Drugs Bind to Their Targets

Question 1

means that a substance/drug binds to a receptor and influences its response to an agonist

Answer 1

antagonism

Question 2

what happens when a competitive antagonist is added to an agonist solution?

Answer 2

a higher concentration of the agonist is needed to generate a given response

Question 3

is agonist efficay changed in the prescence of a competitive antagonist?

Answer 3

no

Question 4

what happens when a noncompetitive antagonist is added to an agonist solution?

Answer 4

agonist efficacy is reduced, but there is no effect on potency

Question 5

where do competitive antagonists bind?

Answer 5

the same binding site as the agonist

Question 6

do competitive agonists elicit a biological response?

Answer 6

no

Question 7

at high enough agonist concentrations, antagonists can be ___

Answer 7

displaced

Question 8

the ratio of agonist EC50 in teh prescence vs. abscence of an antagonists

Answer 8

dose ratio

Question 9

how is the dose ratio measured?

Answer 9

dose ratio = (EC50 in the prescence of an antagonist) / (EC50 control)

Question 10

the x-intercept of a Schlid plot, the pki, reflects the ___

Answer 10

potency of the antagonist

Question 11

noncompetitive inhibition occurs due to antagonist binding at the ____ site

Answer 11

allosteric (different from agonist binding site)

Question 12

a drug that has an allosteric binding site that enhances the effects of an agonist (efficacy/potency)

Answer 12

positive allosteric modulator

Question 13

competitive antagonists bind to the ____ site

Answer 13

orthosteric (same site as the antagonist)

Question 14

is there a direct relationship between the fraction of receptors that are bound to a drug and the biological response?

Answer 14

no

Question 15

refers to the potency of direct binding of a drug to a receptor

Answer 15

Kd (dissociation constant)

Question 16

describes the potency of a drug in the context of measurement of an effect

Answer 16

EC50

Question 17

why can there be a mismatch between binding and effect?

Answer 17

one reason is that there might be more receptors present than are necessary to generate a full biological effect

Question 18

the difference between binding and effect is illustrated by a phenomenon called ___

Answer 18

receptor reserve (see notes for visual)