occupancy theory Flashcards
what is pAx
the negative log of the concentration of antagonist that has a dose ratio of
what are the six assumptions for occupancy theory
(sorry this is such a long one)
-receptors and agonists are specialised for each other
- all agonists can cause the same max response
-drug-receptor interactions are reversible
-all receptors are equally accessible
-receptors don’t interact
-maximum response is when all receptors are occupied
why is it that not all agonists will produce a maximal response
some are partial agonists and will only have a weak response
what do partial agonists act as in the presence of a full agonist
a competitive antagonist
what is an intrinsic activity
ability for a drug to produce a conformational change
if a drug is a full agonist, what will the intrinsic activity be
= 1 (equal to 1)
if a drug is a partial agonist, what will the intrinsic activity be
< 1 (less than 1)
if a drug is an antagonist, what will the intrinsic activity be
= 0 (equal to 0)
what does the concept of ‘spare receptors’ mean
that there are spare receptors within the system that can be occupied to cause a response in low efficacy drugs
why do some drugs not have to bind to all receptors to cause a maximal response
they only have to bind to a small fraction of receptors to cause a response
how can we know if a full agonist has high efficacy or low efficacy
which state they bind to
what is an inverse agonist
an agonist that stabilises a receptor at its resting state
