pharmacodynamics

Question 1

what is pharmacodynamics

Answer 1

the study of the effects of drugs and their mechanism of action

Question 2

what are the 4 categories where drugs exert effect

Answer 2

• receptors
• ion channels
• transporters
• enzyme

Question 3

what is an acellular interaction

Answer 3

no cells to interact with

Question 4

how do receptors work

Answer 4

macromolecules on a cells surface that have an effect when a drug binds to it

Question 5

what are agonists

Answer 5

a drug that interacts with a receptor and initiates a cellular reaction similar to its endogenous neurotransmitter

Question 6

what are antagonists

Answer 6

a drug that interacts with a receptor that is unable to induce a cellular rection

Question 7

what factors affect a drugs affinity to its receptor

Answer 7

• size
• electrical charge
• shape
• atomic composition

Question 8

what is efficacy

Answer 8

• intrinsic activity of a drug that determines its ability to produce an effect - Emax
• the maximum response achievable

Question 9

what is potency

Answer 9

• a measure of necessary amount of the drug to produce an effect of a given magnitude - ED50
• the strength of the drug for the needed effect

Question 10

how does ED50 work

Answer 10

the lower the ED50 the more potent as less of a drug is needed to produce the same effect

Question 11

what is a partial agonist

Answer 11

produces maximal effect but is less than the amount produced by a full agonist

Question 12

what is a full agonist

Answer 12

• has a high affinity for a receptors
• produces maximal response by occupying a fraction of receptors

Question 13

what is the purpose of an antagonist

Answer 13

• prevent agonist from binding
• no effect on biological function
• decreases effect of agonist

Question 14

what are the different types of antagonism

Answer 14

• reversible antagonism
• irreversible antagonism
• non-competitive
• functional
• chemical
• physical
• pharmacokinetic

Question 15

what is reversible antagonism

Answer 15

• able to bind to the receptor but can be released
• higher agonist will displace antagonist

Question 16

what is irreversible antagonism

Answer 16

antagonist binding can’t be displaced = covalently bonded

Question 17

what is non-competitive antagonism

Answer 17

the antagonist binding site is not the active site

Question 18

what is functional antagonism

Answer 18

antagonist that works on a different receptor but results in reducing the effect of the other drug

Question 19

what is chemical antagonism

Answer 19

the chemical combination of an antagonist with the substance it is antagonising

Question 20

what is physical antagonism

Answer 20

based on the physical properties of the drug

Question 21

what is pharmacokinetic anatgonism

Answer 21

when one drug accelerates the metabolism or elimination of another

Question 22

what are the pharmacological actions targeting enzyme

Answer 22

• enzyme inhibitors
• false substrates
• prodrugs

Question 23

what are the different types of competitive inhibition

Answer 23

• reversible - change back to original state
• irreversible - can’t change back

Question 24

what are false substrates

Answer 24

drug molecules which chemically change to form abnormal products that overthrow the normal metabolic pathway

Question 25

what are prodrugs

Answer 25

drugs needing enzyme degradation to convert from inactive to active to have a therapeutic effect

Question 26

what is the function of carrier proteins

Answer 26

to selectively uptake and efflux compounds either unidirectionally or bidrecetionaly

Question 27

how do replacement molecules affect carrier proteins

Answer 27

replacements resemble indigenous molecules so they can travel through carrier proteins as they look the same

Question 28

how do inhibitors affect carrier proteins

Answer 28

prevent transport of molecules

Question 29

how do selective serotonin reuptake inhibitors work

Answer 29

• block uptake of 5-HT by nerve terminals in brain
• increasing 5-HT levels depresses symptoms

Question 30

how do false substrates affect carrier proteins

Answer 30

• out-compete natural ligand for the carrier protein
• transporter takes them up as they resemble the substance in our body

Question 31

example of false substrate on carrier proteins

Answer 31

methyldopa taken up by noradrenaline transporter -> false transmitter a-methylNA -> accumulates and displaces methylNA -> released -> less active than NA on a receptors -> less effective vasoconstriction

Question 32

how do ion channels work

Answer 32

selectively allow passage of ions that can’t go through the lipid bilayer

Question 33

how can drugs affect ion channel function

Answer 33

• activator
• inhibitor

Question 34

what indirect actions can drugs have on ion channels

Answer 34

• intracellular signalling molecule
• produce effects on channel

Question 35

what are acellular substances cause pharmacodynamic effects

Answer 35

• antacids
• heavy metal chelators
• absorbing agents

Question 36

what is the therapeutic index

Answer 36

ratio of dose producing toxicity in half the population to a dose producing a desired response in half the population

Question 37

what is the calculation for therapeutic index

Answer 37

TI = TD50/ED50

Question 38

what does a large therapeutic index show

Answer 38

a wide margin between doses that are effective and doses that are toxic

Question 39

what is the therapeutic window

Answer 39

the concentration range over which a drug produces its therapeutic effect

Question 40

what does a low therapeutic index mean

Answer 40

giving a higher dose that what is minimally required to get the desired effect can cause adverse effects