Mechanism of action - how do drugs bind to receptors

Question 1

define affinity ?

Answer 1

affinity is the attraction between the drug and receptor

so the higher the affinity of the drug for a receptor, the lower concentration of the drug needed to occupy 50% of the drug

Question 2

how is the biological response to a drug recorded ?

Answer 2

the response to a drug can be classified by EC50 and Emax

Question 3

what is EC50?

Answer 3

the measurement taken of the conc of the drug that produces 50% of that response is known as EC50

it is the effective concentration of an agonist that produces 50% of its maximal response

Question 4

what is efficacy ?

Answer 4

the ability of a drug to bind to a receptor and cause a change in the receptors action is termed as efficacy is measured by emax

Question 5

what is term used for a drug that has positive efficacy which activates a receptor to promote cellular response

Answer 5

agonist

Question 6

what is a term used for a drug that has a negative efficacy that binds to receptors to decrease basal receptor activity?

Answer 6

inverse agonist

Question 7

what is a term used for a drug with no a efficacy that binds to the receptors but has no effect on activity

Answer 7

antagonist

Question 8

what is an agonist ?

Answer 8

a drug with a positive efficacy which will activate a receptie to promote cellular response

Question 9

what is an inverse agonist ?

Answer 9

a drug with negative efficacy which will bind to receptors to decrease the basal receptor activity - will cause a decrease when there is activity

Question 10

what is an antagonist?

Answer 10

a drug with no efficacy that binds receptors but has no effect on the ability - these can block the activity of an endogenous ligand from having an effect

Question 11

how is potency measured?

Answer 11

EC50 is used to measure the potency of an agonist

Question 12

what does higher potency of the agonist mean?

Answer 12

a lower ec50

Question 13

name the 2 types of agonims

Answer 13

agonists and partial agonists

Question 14

what are ( full) agonist ?

Answer 14

drugs which elicit the maximum tissue response

Question 15

what are partial agonist ?

Answer 15

that produce less than the maximum response

these cannot produce maximal response even at 100% receptor occupancy

Question 16

why are partial agonist produce maximal response event at 100% receptor occupancy ?

Answer 16

they have no issue binding to the receptor but when it binds to the receptor it does not change the conformation of the receptor which enables the receptor to be maximally activated

Question 17

what are the 2 things that the maximum response of a tissue to a drug is dependent?

Answer 17

the efficacy and tissue properties - a drug may appear to be partial agonist in one tissue and (full) agonist in another