L7 Pharmacodynamics

Question 1

what is the y-axis of Drug Receptor binding curves?

Answer 1

of receptors that are bound

Question 2

what does the Kd tell us in Drug Receptor binding curves?

Answer 2

the affinity of ligand for receptor - the concentration of drug needed to get 50% of receptor population bound to the drug

Question 3

In a Drug Receptor binding curve, as the Kd decreases, what happens to affinity?

Answer 3

increases

Question 4

what is the x axis of Drug Receptor binding curves?

Answer 4

ligand/drug concentration

Question 5

what will go to 100% binding?

Answer 5

true agonists - can still have different affinities

Question 6

what type of affinity do we want in drugs?

Answer 6

high affinity - low dose = not as many side effects

Question 7

what is the x axis in Dose-response curves?

Answer 7

the LOG of the concentration of ligand/drug

Question 8

what does E stand for in Dose-response curves?

Answer 8

effect - the max effect you can get

Question 9

what is the y axis in Dose-response curves?

Answer 9

effect

Question 10

what is EC 50 in Dose-response curves?

Answer 10

concentration at which we are at a 50% max effect

Question 11

what do Dose-response curves tell us about the drug besides effect?

Answer 11

potency of the drug

Question 12

drug-receptor binding curves have ___

dose -response curves have ___

Answer 12

affinity

potencies

Question 13

define spare receptors

Answer 13

when EC 50 is less than Kd

“50% response/effect before we occupy 50% of the receptors” - may only need 10%

Question 14

what does the spare receptor tell us?

Answer 14

we don’t need to bind all receptors to get max cellular response

Question 15

what does ED stand for?

Answer 15

effective dose

Question 16

what is an agonist

Answer 16

binds to receptor and produces an effect in the cell

Question 17

what is an antagonist?

Answer 17

inhibits the action of an agonist, but has no effect in the absence of the agonist
just occupies receptor and prevent effect
don’t want the effects of an endogenous ligand that is produced by the body
“blocker”

Question 18

the drug-receptor complex is directly related to ?

Answer 18

[drug] - extent of receptor activation is proportional to [Drug]

Question 19

what is physiological antagonism

Answer 19

causes a physiological effect that is opposite to that induced by agonist

occurs when drug response mediated by activation of a receptor is antagonized by an opposite response produced by another drug acting on a DIFFERENT RECEPTOR

i.e. histamine (bronchocon) and NE (bronchodil)

Question 20

what is a chemical antagonist?

Answer 20

antagonist inactivates the agonist chemically before it can act - chemical neutralization

i.e. magnesium hydroxide - combines with acids = neutralizing it = prevents the effects of acid on stomach.

Question 21

in a dose-response curve, a competitve antagonist binds ____ to the _____ of the receptor

Answer 21

reversibly

active site

Question 22

in a dose-response curve, antagonists displace the relationship between [drug] and effect to the ____

Answer 22

right

Question 23

in a dose-response curve, antagonists do not effect

Answer 23

efficacy

Question 24

in a dose-response curve, antagonists cause a

Answer 24

loss of potency

Question 25

in a dose-response curve, a noncompetitive receptor antagonist binds to the active site ____

Answer 25

irreversibly - covalently or very high affinity

receptor cannot be activated!

Question 26

a high concentration of the drug in a dose-response curve would not do what

Answer 26

displace the antagonist from the receptor

Question 27

in a dose-response curve, with a noncompetitive receptor antagonist what do you find?

Answer 27

fall in efficacy

Question 28

in a dose-response curve, with a noncompetitive receptor antagonist what do you NOT find a change in

Answer 28

EC 50

Question 29

the ___ antagonist, the ____ decrease in Emax

Answer 29

larger concentration

bigger

Question 30

when are there no spare receptors?

Answer 30

when EC50 and Kd are equal

Question 31

when EC 50 and Kd are equal what do you find

Answer 31

fall in efficacy - not enough receptors unoccupries by antagonist to give full effect response

Question 32

how can you tell if it is a noncompetitive or competitive antagonist?

Answer 32

first see right shift in EC 50
then a drop in Emax
EC 50 change - competitive antagonist
EC 50 no change - noncompetitive antagonist 
Emax change - noncompetitive antagonist
Emax no change- competitive antagonist

Question 33

what is a partial agonist?

Answer 33

agonist that never gives us enough receptor activation to give a 100% biological effect even at max concentration

Question 34

what is the formula for therapeutic window and index?

Answer 34

TI = TD50/ED50

measure the difference between TD and ED
the wider the gap the safer the drug!