receptor ligands

what determines the affinity of a ligand for a target?

• chemical bonds (#, strength)

is the binding of a ligand to a target reversible or irreversible?

• primarily reversible

which affinity is stronger?

100 nM vs 50 uM

100nM

• the lower/smaller # = higher affinity

as the inverse agonist increases, what happens to the activated receptor?

• decreases

what is a partial agonist?

• binds to both active and inactive receptor

T/F: sometimes partial agonists can be used as an antagonist

• true

full agonist

• response increases to maximum

• binds only to active agonists

inverse agonist

• binds to inactive receptor

• reduces active receptors

• removes basal activity by shifting everything to inactive conformation

which one removes basal activity by shifting everything to inactive conformation ?

a) inverse agonist

b) full agonist

c) partial agonist

d) neutral antagonist

a) inverse agonist

partial agonist

• somewhat higher affinity for active receptors

• increase in partial agonist → increase response/effect

• lower maximum than full agonist

neutral antagonist

• response does not change

• kept in 95:5 ratio

• basal activity can not change

neutral antagonists can also include what other ligand? (in therapeutic terms)

• inverse agonist (partial + full)

  • Response is still reduced

what is the difference between dose and concentration?

• dose = in humans/animals

• concentration - in tissue/cells

what is the difference between graded and quantal response?

• graded = numerical value (bpm, bp, mmHg, etc)

• quantal = yes or no

how is the potency (EC₅₀ or ED₅₀) of a drug determined?

• concentration/dose that produces 50% (half) of maximal response

potency looks at the (x/y) axis

• x -axis

efficacy looks at the (x/y) axis

• y axis

where to look for E_^max ?

• plateau of curve

if ED50 is lower, is it more or less potent?

• lower = more potent