Intro to Pharmacology

Question 1

ligand definition

Answer 1

a chemical or compound that binds to a receptor

Question 2

agonist definition

Answer 2

a compound that binds to an activated a receptor

Question 3

antagonist definition

Answer 3

a compound that reduces the effect of an agonist at a receptor

Question 4

partial agonist

Answer 4

a low efficiency agonist that is unable to elicit the maximal response from a receptor, irrespective of the concentration applied

Question 5

affinity definition

Answer 5

a measure of the equilibrium constant of the reversible reaction between a drug (agonist or antagonist) and a receptor

Question 6

efficacy definition

Answer 6

a measure of the magnitude of the (cellular) response produced when an agonist binds to receptor

Question 7

potency definition

Answer 7

a measure of the concentration f a drug at which it produces an effect of a given magnitude

Question 8

specificity definition

Answer 8

a measure of the number of receptor sites that a given drug may bind to or the range of effects it may produce

Question 9

selectivity definition

Answer 9

the degree to which a drug binds to a given receptor site relative to other sites (related to affinity)

Question 10

what is a drug

Answer 10

a chemical substance intentionally administered that alters body function, which is used for the prevention of treatment of a disease

Question 11

what is the difference between a drug and a medicine

Answer 11

a medicine contains other substances
- stabilisers/ solvents
- more convenient

Question 12

what do drugs target (4)

Answer 12

receptors (most targeted)
enzymes
carrier molecules (transporters)
ion channels

Question 13

what does it mean if both agonist and antagonist can act on a receptor

Answer 13

there must be chemical similarities between them
there must also be chemical differences (why one activates and one blocks)

Question 14

affinity lock and key analogy

Answer 14

affinity is how well the key fits the locke

Question 15

efficacy lock and key analogy

Answer 15

efficacy is how well the key can turn the lock
efficacy is graded

Question 16

receptor occupancy

Answer 16

hyperbolic relationship
- as the receptor needs to be occupied to be activated in order to elicit a response, the dose-response curve of an agonist is also hyperbolic

Question 17

dose response curves

Answer 17

allows estimation of the maximal effect/ response (Emax) a drug can produce
- estimate the conc. of a drug needed to produce a half maximal response (EC50)
- EC50 used to compare efficacy between drugs

Question 18

measuring EC50 on hyperbolic curves

Answer 18

is harder
- common practice to plot the same data but on a semi-log scale

Question 19

high potency =

Answer 19

high affinity for the receptors

Question 20

do antagonists posses affinity and/or efficacy

Answer 20

only affinity
no response, no efficacy

Question 21

mechanisms of antagonist

Answer 21

by binding to the same site as the agonist and competing with it (competitive)
binding to a different site to the agonist, which causes a change in the receptor to prevent or restrict agonist binding (non-competitive)

Question 22

competitive antagonists

Answer 22

binds to the endogenous ligand and competes for binding
concentration and affinity determines the ‘winner’ of the competition
no response/ response
effect of a competitive antagonist can be overcome by increasing agonist concentration

Question 23

non-competitive antagonists

Answer 23

binds to a different site -> conformational change restricts agonist binding
cannot be overcome by increasing agonist concentration
partial response