pharmacodynamics ppm Flashcards
what are the two components of agonist actions
affinity - the ability to bind to the receptor
efficacy- it’s bality to produce a response
what does the KD value show
the kd value measures the affinity
- LOWER KD = HIGHER AFFINITY
what does the scatchard plot analysis show (the graph)
this meshes the bound radioligand and provides a info on the kd value
the X axis represents the B max value (this shows the saturation - the amount of active sites)
and the slope of the line is -1/KD = the inverse of this will be th kd value which will show you the affinity
what does the efficacy of the drug depend on
- efficacy of the drug receptor interaction depends on whether the receptor is occupied and activated
this can cause the opening of the ion channels, activation of GPCRs or activation of enzymes
what is bioassay
thais measures the biological response of living tissue to a drug or chemical entity
it can be done on animals (in vivo ) or tissues or cells (in vitro)
what is the purpose of dose response curves
to quantify the response of tissues to a drug
in this you can get the email value ( this teh is the maximum response) and the ec50 (conc or dose required to produce the 50% maximal dose - this can be used to measure POTENCY ( this sis how much of the drug is needed to elicit the needed response - however this is not used to get the accurate KD value because there are spare receptors which will allow a full response without 100% occupancy
maximal efficacy ND partial agonist
- efficacy is the measure of an agonists ability to levity a response by activitating a receptor
maximal efficacy is teh largest effect a drug can produce on a tissue
partial agonists only produce a small maximal response
full efficacy = 1
partial agonists efficacy = -1
what is inverse agonists
inverse agonists are ligands that reduce the fraction of receptors in an active conformation they bind to receptors and reduce constitutive activity in the absence of conventional agonists
what are the general classes of antagonists (explain)
- chemical antagonist - two substances combine in a solution and the effect of the active drug is lost
- physiological anatagonusts - two drugs act in a common pathway but have opposite effects
- pharmacokinetic antagonists - the rate of degradation of an active drug may be influenced by other drugs which increases it hepatic metabolism
- competitive antagonist - binds to a receptor blocking the binding and action of an agonist
- non competitive anatagonust - bind to alternative site off the receptor or downstream from the receptor activation and blocks component of signal transduction pathway.
antagonist/ agonist efficacy
- full agonist = high efficacy
partial agonist - low efficacy - antagonist - no efficacy - no response
competitive antagonism and their effects
reversible (competitive)
- binds to receptor to prevent agonist from binding and activation
irreversible
- bonds and forms irreversible bonds with receptors
- permanently prevents agonist from binding
when these are introduced this causes a rightward shift of agonist dose response curve
no change in EMAX
what are the effects if competitive anatagonism
- right shift of agonist dose response curve
- no change in emax value
- parallel shift of agonist dose response curves
- same for, of agonist dose response curve
what a the effects of irreversible antagonism
- agonist curve do not have the same form
- emax of agonist does response curve reduces
- ec50 increases
- antagonism cannot be surmounted
what is non competitive antagonism
- binds to non antagonist site
- reduces slopes and emax
- changes ec50
explain the two state hypothesis of agonist receptor interactions
receptors exist in two states active and inactive, agonists bind to the active state and induce a response
