Pharmacodynamics definitions

Question 1

metric prefix subdivision in order of siza

Answer 1

molar –> millimolar –>. micromolar –> nanomolar –> picomolar

Question 2

Log10 of number

Answer 2

power by which 10 has to be raised to get that number

Question 3

what is the log number of 1000

Answer 3

10 x 10 x 10 = 10^3 log1000= 3

Question 4

Log10 of 0.000001m

Answer 4

Log10^ -6

Question 5

A ligand =

Answer 5

a substance that can interact with a target protein or receptor • Binds to specific site on that signalling protein • Ligands can endogenous (hormones, ions or NT) or exogenous

Question 6

An agonist=

Answer 6

a substance which binds to a receptor and activates the receptor to then produce a measurable biological response

Question 7

An antagonist=

Answer 7

a substance which binds to a receptor, but does not produce a biological response • block the effects of agonists

Question 8

Affinity=

Answer 8

is a measure of the strength of which a ligand or drug binds to a receptor

Question 9

What is the measurement used to define affinity?

Answer 9

Affinity is measured by Kd

Question 10

Kd=

Answer 10

the concentration of ligand at which 50% of all available receptors are bound • lower the value of Kd the greater affinity

Question 11

Intrinsic efficacy=

Answer 11

A term used to describe the ability of a ligand to generate the active form of the receptor (R*- active form of receptor)

Question 12

agonist has

Answer 12

intrinsic efficacy and affinity

Question 13

antagonist has

Answer 13

affinity but no intrinsic efficacy

Question 14

Ligand efficacy=

Answer 14

ability to cause a measurable biological response

Question 15

Clinical efficacy=

Answer 15

relates to response with therapeutic value e.g, does the drug reduce blood pressure

Question 16

Agonist potency=

Answer 16

the concentration of a drug that evokes 50% of its maximal response (Emax) -The term EC50 is used to represent this concentration

Question 17

The smaller the EC50

Answer 17

• the higher the potency of the drug

Question 18

Partial agonist=

Answer 18

ligands that evoke responses that are lower than the maximal response of the full agonist (i.e they have lower Emax values)

Question 19

Compared to a full agonist, a partial agonist has

Answer 19

lower intrinsic efficacy • Partial agonists have a lesser ability to activate the receptor • Therefore doesnt evoke the maximal biological response

Question 20

which drug has the highest intrnsic activity?

Answer 20

B

Question 21

Which drug has the highest potency?

Answer 21

A

Question 22

measuremnts used in the binding curves

Answer 22

Kd and Bmax

Question 23

concentration-response curve measurements

Answer 23

EC50 and Emax

Question 24

Bmax

Answer 24

the maximum amount of drug/luigand which can bind to the receptor

-can be used to measure the density of the receptor site in a particular tissue e.g. fluorescent tagging

Question 25

How to measure kd on a binding curve?

Answer 25

Question 26

how to emasure EC50 on a response curve?

Answer 26

Question 27

antagonism can be achieve by

Answer 27

1) Antagonism of the action of agonist at its receptor using a ligand
2) Antagonism of a cellular tissue event being mediated by one mechanism by another mechanism (functional) antagonism

Question 28

3 main types of antagonism

Answer 28

Reversible competitive antagonism

Irreversible competitive antagonism

Non competitive antagonism

Question 29

reversible compeitive antagonsim

Answer 29

◦Takes place at the same binding site as the endogenous ligand (orthosteric site)

◦Interaction is by relatively weak, non covalent bonding

Question 30

Irreversible competitive antagonism

Answer 30

◦Takes place at the same binding site as the endogenous ligand (orthosteric site)

◦Irreversible interaction reflects high affinity with very slow dissociation- may be covalent binding

Question 31

Non competitive antagonism

Answer 31

◦Binding occurs at separate allosteric site- no competition for orthosteric site access

◦Interaction can be either lo or high affinity and could include non covalent and covalentbonding

Question 32

Experiments show that only 10% of M3 receprtors in airway smooth muscle need to bind Ach to achieve maximal contraction, The EC50 for Ach is around 10^-7M compared to a Kd = 10-6M

what pharmacodynamic principele xplains the difference between the EC50 and Kd for ACh at the M3 receptor

Answer 32

Spare muscarinic M3 receptors

Question 33

a new drug Painex developed rto reduce chronic pain acts on a subset of glutamate receptors int he CNS. With increasing cocnenration, painex increases the Kd for glutamate. At higher cocnenretion it reduces the Emax of glutamate by 50%. What best describes the likely pharmacodynamic action of this drug?

Answer 33

non-competitive antagonist