pharmacodynamics

Question 1

what is pharmacodynamics

Answer 1

how drugs interact with receptors

Question 2

what is a ligand

Answer 2

can refer to drug, hormone or neurotransmitter too. Its something that binds to the receptor.

Question 3

what is affinity

Answer 3

how well the drug molecule likes interacting with that receptor to form complex. high affinity means it binds easily higher= stronger binding. dictates how much drug is administered.

Question 4

what is efficacy

Answer 4

cause a measurable response. ability to generate a response. governs activation of the receptor as this is part of creating a response. this is also obviously cell and tissue dependant as some muscle may contract easier than others.

Question 5

what is an agonist

Answer 5

a molecule which binds and activates a receptor. must have intrinsic efficacy and efficacy

Question 6

what is potency

Answer 6

how good a drug is at eliciting a response. can be shown using EC50. depends on both affinity and intrinsic efficacy. (e.g how well muscle contracts). this also dictates how much drug need to give. if works very well then don’t need to give much

Question 7

what is a partial agonist

Answer 7

only gives half response. all receptors are occupied but still not full response. this is because they cannot turn receptor into active shape as well as full agonists can

Question 8

what is moles equation and what do we use it for

Answer 8

moles=mass/mr. use it for drugs. 2 molecules may have very different molecular weights so even if have equal number of molecules due to the difference in weight they will have very different molar concentrations

Question 9

what is avagadros constant and what is it used for

Answer 9

each mole contains 6x10 to the power of 23. used to find out how many molecules/atoms there are present

Question 10

pharmacological efficacy vs clinical efficacy

Answer 10

pharmacological efficacy causes blood vessel to dilate but the clinical efficacy causes blood pressure to decrease. = generic term

Question 11

how do we measure binding

Answer 11

add radioactive label to ligands = radioligand. seperate the ligand bound and the amount of ligand not bound. if increase the conc of ligand more will bind. can draw graph to show proportion of receptors bound against conc of drug.

Question 12

what is the Bmax

Answer 12

the maximum binding capacity of ligand to receptors. found on graph as you would the vmax

Question 13

how do you find out kd from a proportion of ligands bound vs drug conc graph (dissociation constant)

Answer 13

find 50% of proportion of receptors bound and draw line across and then down

Question 14

what does the kd tell you

Answer 14

lower kd then ligand will have higher affinity. logical because lower means 50% bound at lower conc. helps estimate affinity

Question 15

what is a log (10) and effect it has on graph

Answer 15

power by which 10 has to be raised to to get thet number. hyperbola graph will turn sigmoidal. usually how drug graphs are drawn. remember than -3 log10 is 0.001M which is much larger than -9log10 which is 0.0000000001M

Question 16

what is the scale on the x-axis of a drug sigmoidal graph

Answer 16

always from -11log10 (largest) to -7log10(lowest)—-dont know exactly??

Question 17

how do we measure response rate

Answer 17

higher drug conc leads to increased response. plot this and gives you hyperbola graph. from this can find out emax and ec50. using log scale converts it to sigmoidal curve

Question 18

what is Emax

Answer 18

it is the maximum response a ligand can create.

Question 19

what is EC50

Answer 19

it is the effective concentration giving 50% of the maxmimal response. find 50% of response and draw across and down. shows the potency of a drug

Question 20

how to distinguish between dose and concentration on a response graph

Answer 20

concentration will be the known conc in a test tube and a dose is where you don’t know the exact conc at the receptor because its a dose.

Question 21

how asthma is treated and what is the problem

Answer 21

target beta 2 adrenal receptors causing relaxation of the bronchioles using an agonist (usually noradrenaline/adrenaline) but the problem is that this will also cause an increase in heart rate because the heart also has beta 2 adrenoreceptors = bad news

Question 22

solution to activating only beat 2 receptors in lung and not heart

Answer 22

use a selective drug which preferably binds to lungs than heart. kd will show the affinity and use drug which has much higher affinity for lung than heart. (this value will be lower). (can also be measured by ability to create response- efficacy)

Question 23

what is the concept of spare receptors

Answer 23

only need a certain number of receptors to be bound for a response. if more are bound than needed get same response. these extra receptors that are bound are spare receptors. however, more receptors could be due to amplification or due to the fact that a muscle can only contract by a certain amount for example

Question 24

why we need spare receptors

Answer 24

spare receptors alter potency. more receptors = lower concentration of drug needed for biological response. this means the sigmoidal curve will shift to left every time spare receptors increase as concentration of agonist needed is decreasing

Question 25

receptor numbers are not fixed why?

Answer 25

increase with low activity and decrease with high activity of drug use. this is bad because after a while a drug may stop working

Question 26

what is intrinsic activity

Answer 26

the size of the response of a partial agonist. if has larger response then also has larger intrinsic activity

Question 27

how are partial agonists important in clinical settings

Answer 27

allow a more controlled response, can act as antagonist if high levels of full agonist or work in absence of endogenous ligand

Question 28

example of partial agonist use

Answer 28

beupamorphine is partial agonist of opioid receptors. this means that its more controlled than morphine which is the full agonist. danger of morphine is that is can cause respiratory depression.

Question 29

example of partial agonist use (heroin)

Answer 29

also used used in opiod addict therapy. beupamorphine occupies receptors preventing heroin from binding and therefore will inhibit its affect and able to wean addict off heroin as they are not feeling full response (beupamorhpine)

Question 30

why does withdrawal occur when using partial agonists of heroin

Answer 30

when taking drugs the receptors are down regulated because they are over stimulated. this means when heroin is stopped there are not enough receptors for endogenous ligand to do its job so has the opposite effect of what you where taking drug for. e.g heroin causes pain

Question 31

what is reversible competitive antagonism

Answer 31

relies on dynamic equilibrium between ligands and receptors. agonist and antagonist compete for receptor. if increase antagonist then more likely for it to be binding to receptor. on graph of response vs antagonist coonc as antagonist increase the response decrease

Question 32

what is IC50

Answer 32

the concentration of an antagonist giving 50% inhibition of response of response vs antagonist conc graph

Question 33

what is IC50

Answer 33

the concentration of an antagonist giving 50% inhibition of response of response vs antagonist conc graph. regulated by affinity of antagonist for receptor. IC50 therefore shows potency of antagonist. higher = more potent. elicits a better response. better at inhibiting the receptor.

Question 34

competition between the agonist and antagonist. why can a full biological response always be ellicted

Answer 34

because they are competative. as antagonist conc increases, more agonist is required to outcompete it. draw this on a graph

Question 35

what is irreversible competitive antagonism

Answer 35

occurs when antagonist doesn’t dissociate from the receptor due to high affinity or a covalent bond. not surmountable. increasing agonist conc will not be able to outcompete antagonist. draw graph of this

Question 36

what is non-competitive antagonism

Answer 36

endogenous ligand binds at the orthosteric site and the non-competitive inhibitor will bind at the allosteric site. can enhance or inhibit effects of agonist. control its intrinsic efficacy

Question 37

what is non-competitive antagonism

Answer 37

endogenous ligand binds at the orthosteric site and the non-competitive inhibitor will bind at the allosteric site. can enhance or inhibit effects of agonist. control its intrinsic efficacy. used for HIV treatment which blocks HIV from getting into white blood cells via the receptor it usually uses.