9 Pharmacodynamics

Question 1

binding site bs receptor?

Answer 1

binding site-can bind substance but are not themselves capable of initiating response
receptor-can bind a substance and are capable of initiating a subsequent response

Question 2

What is the percentage of receptors occupied dependent on?

Answer 2

the drugs

1. affinity
2. concentration

Question 3

What does KD=

Answer 3

[D][R]/[DR]

Question 4

What KD will drugs that have high affinity for receptors have?

Answer 4

low Kd values

Question 5

WHat does KD the affinity constant represent ?

Answer 5

the concentration of that drug required to occupy 50% of a receptor population

Question 6

What is the fractional occupancy equation tell you? What is it

Answer 6

-the binding of drugs to a receptor, dependent on drug affinity and drug concentration

1/(1+(KD/[D]))

Question 7

How many log KD units to get to 91% occupied?

Answer 7

3 log units of concentration to occupy 91% of receptors

Question 8

What is the magnitude of the response a function of?

Answer 8

some function f of the total number of receptors occupied

Question 9

Does selectivity decrease as a dose increases?

Answer 9

yes

Question 10

What is the dose response relationship?

Answer 10

increasing the dose increases the effect in a gradual manner but not right

Question 11

What is potency?

Answer 11

the concentration or dose of a drug needed to produce 50% of that drugs maximal response

Question 12

What is maximal efficacy?

Answer 12

-the maximal response produced by the drug

Question 13

Can biological activity be determined from fractional occupancy?

Answer 13

no!

equal affinity but different biological activity

Question 14

Are efficacy and potency independent properties of a drug?

Answer 14

yes

Question 15

What is the clinical effectiveness of a drug dependent on?

Answer 15

Maximal efficacy (Emax) not potency (ED50)

Question 16

To determine spare receptors you can take away number of total receptors, how can you tell when you exceed the reserves?

Answer 16

you see a reduction in E max

so like if it takes 20 receptors for E max and you take 10 away from 20 you cant get to Emax

Question 17

Competitive antagonism

Answer 17

Surmountable!

• shift to the right in the DR Curve
• increases ED50
• No change in Emax

Question 18

Competitive Antagonism

Answer 18

Insurmountable
-decrease Emax
-no change in ED50
(bad drug taking receptors and good drug has no reserves)

Question 19

What is antagonism by partial agonists?

Answer 19

1+1/2 is less than 1

-decreases total response by decreasing full agonist component

Question 20

What is chemical antagonism, physiological antagonism, and biologic antagonism?

Answer 20

chemical-chemical inactivation of drug

physiologic- opposing pathways to antagonize the effects of a drug

biologic-drug may affect metabolism of another drug

Question 21

What is the quantal dose response curve?

Answer 21

the relationship between drug dose and a specified effect in a population of individuals
-cumulative frequency distribution of doses of a drug that produce a specified effect

Question 22

What is the ED50 in the quantal dose response curve?

Answer 22

-median effective does

Question 23

How do you know an index of selectivity from a quantal dose response curve/

Answer 23

comparing ED50 for specified effects

Question 24

What can you compare on an quantal dose response curve to estimate the degree of safety for a drug for a specified effect? (therapeutic index )

Answer 24

LD50/ED50

Question 25

What is the therapeutic window?

Answer 25

a more clinically relevant index of safety

-dosage range between minimum affected therapeutic dose and the minimum toxic dose