Session 6: Pharmacodynamics

Question 1

What is a millimolar in standard form? (mM)

Answer 1

10^-3

Question 2

What is a micromolar in standard form? (Mew M)

Answer 2

10^-6

Question 3

What is a nanomolar in standard form? (nM)

Answer 3

10^-9

Question 4

What is a picomolar in standard form? (pM)

Answer 4

10^-12

Question 5

Most drugs bind reversibly to receptors. What is reversible binding?

Answer 5

Binding governed by association and dissociation.

Question 6

Define ligand.

Answer 6

A molecule or Ion which binds to a specific receptor.

Question 7

What is the binding of a ligand to a receptor governed by?

Answer 7

It’s affinity.

Question 8

Define ligand efficacy.

Answer 8

The ability of a ligand to cause a response.

Question 9

What is receptor activation governed by?

Answer 9

Intrinsic efficacy of a ligand.

Question 10

What do agonist ligands have?

Answer 10

• affinity (can bind to the receptor)
• intrinsic efficacy (ability to activate receptor)
• efficacy (ability to cause a response)

Question 11

What do antagonist ligands have?

Answer 11

• affinity ONLY(can bind to the receptor)

Prevents a response by preventing endogenous ligands from binding.

Question 12

How can drug-receptor interactions be measured?

Answer 12

Radioligands

Question 13

What is Kd

Answer 13

Dissociation constant

Question 14

What is Ec50?

Answer 14

POTENCY: Effective Concentration which gives 50% of the maximal response.

Question 15

Define concentration in relation to drug administering.

Answer 15

The concentration of drug at the site of action. E.g. receptor in tissues and cells

Question 16

Define dose in relation to drug administering.

Answer 16

The concentration at the site of action is unknown.

Question 17

What is the potency sum?

Answer 17

Affinity + Efficacy AND the number of receptors on a cell

Question 18

When are spare receptors present?

Answer 18

• signal transduction becomes amplified later on

- response limited by post-receptor event I.e. A muscle can only contract so hard

Question 19

Why are spare receptors present?

Answer 19

To increase sensitivity, I.e. It allows responses at low concentration of agonists

Question 20

TRUE OR FALSE: receptor numbers are fixed.

Answer 20

False: they tend to increase with low activity to up-regulation and visa versa due to physiological, pathological or drug-induced changes

Question 21

What is a partial agonist?

Answer 21

A ligand which does elicit a maximal response.

Question 22

What is usually different about partial agonists?

Answer 22

Usually have lower intrinsic efficacy.

Question 23

Give 3 reasons why partial agonists are important.

Answer 23

1. Allow a more controlled response
2. Work in the absence/ low levels of endogenous ligand
3. Can act antagonistic if levels of full agonist are high

Question 24

Give an example of a partial agonist.

Answer 24

Buprenorphine (higher affinity I.e. Lower Kd but lower efficacy than morphine)

Question 25

TRUE OR FALSE: increaseing the receptor number can change a full against into a partial agonist.

Answer 25

False: other way round silly!

Question 26

What is IC50?

Answer 26

The concentration of antagonist giving 50% inhibition.

Question 27

What impact do reversible competitive antagonists have on a concentration-response curve graph?

Answer 27

Shift to the right- think about it, the Kd will increase hence the affinity for the agonist ligand to the receptor will decrease with more molecules of competing ligand present:)

Can you tell I’ve been making these cards for too long now?