Drug Receptor Theory

Question 1

What are the molecular targets for drugs

Answer 1

Ion channels
Transporters
Enzymes

Question 2

What are the types of receptors for drugs?

Answer 2

Ionotropic
Metabotropic
Tyrosine kinase
DNA linked

Question 3

What are ionotropic drug receptors?

Answer 3

On or inside the cell membrane
Fast response - milliseconds
Ligand gated - binding of ions
Increases or decreases action potentials

Question 4

What are metabotropic drug receptors?

Answer 4

G-protein coupled receptors
On cell membranes
Medium response - minutes
Ligand gated - hormones and neurotransmitters
(Ligand binds with receptor and then receptor binds with g-protein to transfer ligand)
Example; histamine receptors

Question 5

What is a tyrosine kinase drug receptor?

Answer 5

On cell membranes
Medium response - seconds to mins
Ligand gated - hormones and growth factors
Example; insulin receptors

Question 6

What are DNA linked drug receptors?

Answer 6

In the cytoplasm of cell
Slow response - hours
Ligand gated - hormones and glucocorticoids
Activates or inhibits gene transcription

Question 7

What is an agonist drug?

Answer 7

Drug binds to receptor and produces a response
(Has both affinity and efficacy)

Question 8

What is an antagonist drug?

Answer 8

Drug binds to receptor and blocks response
(Only has affinity)

Question 9

What is a partial agonist drug?

Answer 9

Drug agonists which cannot reach 100% response
(Cannot activate enough receptors)

Question 10

What is drug affinity?

Answer 10

How well a drug binds to receptors
(High affinity = less receptors need binding to, to produce effect)

Question 11

What is drug efficacy?

Answer 11

How well a drug activates the receptors
(High efficacy = less receptors need activating to produce effect)

Question 12

What is Kd?

Answer 12

The concentration of the drug needed to occupy 50% of receptors

Question 13

What is the EC50?

Answer 13

The concentration of the drug that gives you 50% of the response

Question 14

Why do high efficacy drugs not need to fill every receptor to produce a 100% response?

Answer 14

Because a high efficacy drug has an EC50 much lower than the Kd
This means the agonist does not need to occupy 50% of the receptors to reach 50% response, it can occupy less.

Question 15

What is the potency of a drug?

Answer 15

How much of the drug needed to produce the maximum effect

Question 16

What are the types of drug antagonism?

Answer 16

Competitive
Non-competitive
Uncompetitive
Physiological

Question 17

Define competitive drug antagonism

Answer 17

Binds at the agonist recognition site, preventing access of normal ligand
Can be reversible or irreversible

Question 18

Define non-competitive drug antagonism

Answer 18

Does not bind at the agonist site, but binds elsewhere to cause conformational change to binding site inhibiting normal agonist binding

Question 19

Define uncompetitive drug antagonist

Answer 19

Binding occurs to an activated form of the receptor

Question 20

What are drug antagonists?

Answer 20

Prevent agonists from activating their receptors
Can be reversible or irreversible

Question 21

Define reversible competitive antagonism

Answer 21

Will eventually dissociate allowing agonist to bind
Temporarily reduces the amount of receptors
Effects can be overcome by increasing amount of agonist

Question 22

Define irreversible competitive antagonist

Answer 22

Reduces number of available receptors
Eventually will have no receptors for agonist to bind to