W8 - Efficacy and partial agonists Flashcards
What is efficacy
ability of a drug to activate a receptor and cause a response
what is the measurement of binding
affinity
what is the measurement of effect
efficacy
what is emax
maximum response that an agonist can achieve
what is ec50
concentration of agonist required to produce 50% of the emax potency
what is the equation for fractional occupancy
ligand/ligand + kd
what is kd
dissociation constant and is a measure of affinity
how can we tell the difference between a full agonist and a partial agonist on a crc
full agonist will have a fractional response of one
partial agonist has fractional response of <1
how do we order efficacy
we use emax
how do we order potency
we use ec50
in cases where partial agonists provide the maximal response what has this meant
stimulus from drug receptor must be amplified to give the response
what does the stimulus in amplification rely upon
occupancy of receptors by drug
intrinsic efficacy of drug
is the statement that the response is not directly proportional true or false
true
what are reserve receptors
a proportion of receptors in a tissue are never used, these are reserve receptors
what doe the existence of reserve receptors mean
Signal amplification must occur i.e. The tissue contributes to the effect and begins to explain tissue specificity
