principles of drug action: week 5

Question 1

pharmacodynamics

Answer 1

what a drug does to the body - biological effects/mechanism of action

Question 2

pharmacokinetics

Answer 2

what the body does to a drug (absorption, distribution, metabolism, and excretion of drugs and metabolites

Question 3

what is a drug?

Answer 3

any synthetic or natural substances used in treatment, prevention, or diagnosis of disease

Question 4

why should drugs act with selectivity?

Answer 4

to be useful as a therapeutic agent

Question 5

how do drugs act?

Answer 5

by binding to target molecules

Question 6

where does drug selectivity result from?

Answer 6

chemical structure of the drug; the target only recognising ligands with a specific type

Question 7

drugs act by binding to regulatory proteins such as…

Answer 7

enzymes, carrier molecules, ion channels, receptors

Question 8

2 important additional drug targets

Answer 8

RNA & DNA

Question 9

receptors

Answer 9

macromolecules which mediate biological actions of hormones and neurotransmitters

Question 10

what is an agonist?

Answer 10

a drug that binds to a receptor to produce a cellular response

Question 11

antagonist

Answer 11

a drug that blocks the actions of an agonist

Question 12

how do agonists act?

Answer 12

bind to receptors to activate them

possess affinity and efficacy

Question 13

what is affinity?

Answer 13

strength of association between ligand and receptor

Question 14

low affinity

Answer 14

fast dissociation rate

Question 15

medium affinity

Answer 15

moderate dissociation rate

Question 16

high affinity

Answer 16

slow dissociation rate

Question 17

efficacy

Answer 17

the ability of an agonist to evoke a cellular responses

Question 18

how do antagonists act?

Answer 18

bind to receptors but don’t activate them
possess affinity but lack efficacy
block receptor activation by agonists

Question 19

relationship between agonist concentration and receptor occupancy

Answer 19

as agonist concentration increases, percentage receptor occupancy increases

Question 20

concentration/dose response relationship - linear plot

Answer 20

relationship between concentration/dose and response is hyperbolic

Question 21

the equation for the relationship between drug concentration and effect

Answer 21

E=(Emax x C)/(C + EC50)
E= effect observed at conc.
Emax= maximal response produced by the drug
EC50=conc. of drug that produces 50% maximal effect.

Question 22

concentration/dose response relationship - semi-logarithmic plot

Answer 22

relationship between concentration/dose and response is sigmoidal

Question 23

competitive antagonism

Answer 23

biding of agonist and antagonist occurs at the same site and is, therefore, competitive and mutually exclusive.

Question 24

non-competitive antagonism

Answer 24

agonist binds to orthosteric site and antagonist binds to separate allosteric site - therefore not competitive.

Both may occupy receptor simultaneously but activation cannot occur when the antagonist is bound.

Question 25

how competitive antagonists affect the agonist concentration-response curve

Answer 25

cause a parallel rightward shift of the curve with no depression of maximal response

Question 26

how non-competitive antagonists affect the agonist concentration-response curve

Answer 26

depress the slope and maximum of the concentration-response curve, but do not cause a rightward shift.