introduction to drug action

Question 1

Receptor:

Answer 1

(pharmacology) class of cellular macaromolecules that are concerned specifically w chemical signalling

Question 2

Pharmacology:

Answer 2

study of how the function of tissues and organs is modified by chemical substances

Question 3

Selectivity:

Answer 3

ability of a drug to distinguish between different molecular targets within the body

Question 4

Ligand:

Answer 4

substance bound to protein

Question 5

Pharmacology:

Answer 5

what a drug does to the body

Question 6

Pharmacokinetics:

Answer 6

what the body does to a drug

Question 7

Drug:

Answer 7

A chemical that affects physiological function in a specific way

Question 8

Medicine:

Answer 8

chemical preparation containing one or more drugs; therapeutic effect

Question 9

• Drug must act selectively for specific receptor

Answer 9

i.e. must have high degree of specificity for the binding site

Question 10

Specificity is a reciprocal arrangement:

Answer 10

certain drugs bind only to certain receptors.

Question 11

Importance of specificity:

Answer 11

drug specificity reduces amount of side effects as no other receptors are activated

Question 12

Rate at which ligand receptors form is

Answer 12

equal to rate that they deform (this is conc dependent)

Question 13

Ka :

Answer 13

concentration of ligand to occupy half of receptors

Question 14

lower Ka →

Answer 14

greater the affinity of ligand for receptor

Question 15

Agonist:

Answer 15

drug that binds to receptor to produce cellular response

Question 16

Antagonist:

Answer 16

drug that reduces or inhibits the actions of agonist by binding to same receptor

Question 17

Affinity:

Answer 17

how strongly medication binds to its receptor

Question 18

higher affinity =

Answer 18

higher potency

Question 19

Efficacy:

Answer 19

maximal effect medication can produce (EMAX)

Question 20

Potency:

Answer 20

amount of drug required to produce a desired effect

Question 21

Efficacy:

Answer 21

maximum response achievable from drug

Question 22

1st stage governed by

Answer 22

affinity

Question 23

2nd stage governed by

Answer 23

efficiacy

Question 24

EC50:

Answer 24

concentration of drug where 50% of effect (response) is produced

Question 25

maller EC50 →

Answer 25

less medication needed to get

Question 26

halfway EMAX→

Answer 26

more potient

Question 27

Partial agonist:

Answer 27

response is sub-maximal, even when all receptors occupied

Question 28

Competitive antagonism

Answer 28

• Binding of agonist and antagonist occur at same (orthosteric) site

Decreased - potiency, NO effect on efficacy (EMAX)

Question 29

Non-competitive antagonism

Answer 29

• Agonist binds to allosteric site
• Shape of receptor alters, ligand can no longer bind

Decreased efficacy (EMAX), NO effect on potiency

Question 30

Reversible competitive antagonist

Answer 30

• Antagonist competes with agonist for same binding site on receptor
  
  • inhibition can be overcome w increased ligand concentration
• Most common antagonist action

Question 31

Chemical antagonism:

Answer 31

antagonist combines in solution w chemical being antagonised

Question 32

Physiological antagonism:

Answer 32

2 agonists produce opposing physiological actions which cancel each other out

- e.g., adrenaline relaxes bronchial smooth muscle reducing the bronchoconstriction of histamine

Question 33

• Pharmacokinetic antagonism:

Answer 33

Antagonist reduces concentration of active drug at its site of action
- e.g., phenobarbitone increases hepatic metabolism of the anticoagulant drug warfarin