Drugs: Quantitative Action Flashcards
define affinity
the strength of and chemical forces involved in the association of a drug with the receptor
define efficacy
ability of a drug to activate the receptor and produce a response.
it is the property that determines the ability of the drug to change the receptor so that a (cellular/ tissue) response is triggered
define antagonist
a drug that combines with the receptor without producing a response (thus, it has affinity but
zero efficacy).
what determines the probability that a drug occupies the binding site?
drug affinity for the site
drug concentration
what position does a drug molecule reside in within the protein binding site?
the position of minimal free energy
what is the law of mass action?
the rate of a chemical reaction is proportional to the concentrations of the reating substances
if Ntot = total number of receptors
NAR = receptors occupied by a ligand A
NR = receptors with no ligand bound
what does Ntot =
what does [R]tot =
Ntot = NAR + Nr
[R]tot= [AR] + [R]
(as you divide the top equation by volume)
what are the units of concentration of a receptor?
if soluble = molar units
if in the plasma membrane they are insoluble therefore we use occupancy
what is the definition of occupancy?
the proportion of receptors that are occupied and free respectively
what do PAR and PR =
PAR = NAR/Ntot
PR = NR/Ntot
