Receptors 4 Flashcards
What is reversible competitive antagonism?
When the antagonist binds to the same receptor site as the agonist. The blockade of the antagonist can be overcome by increasing the concentration of the agonist and the maximum efficacy can still be reached.
produces parallel shift in log conc-effect curve
What is irreversible competitive antagonism?
The dissociation of antagonists is very slow and there is little to no displacement. Covalent bonds are formed to the receptor. The size of the maximal response is decreased with increasing concentration of antagonist.
no change in antagonist occupancy when agonist applied
What is non-competitive antagonism?
When the antagonist blocks the events that lead to the response. It has a similar graph to the irreversible competitive antagonist graph. Th antagonist binds to a different receptor site.
What are allosteric moderators?
Drugs that work in the same way as non-competitive antagonism and bind to an allosteric site. They can change the shape of an agonist binding site and can increase or decrease affinity.
What is chemical antagonism?
Two drugs combine in solution so that the effect of the active drug is lost.
What is pharmacokinetic antagonism?
When one drug reduces the concentrations of an active drug at its site of action, for example changing the rate of metabolism can alter how quickly the drug is removed from the body and changing the rate of absroption can result in more or less drug at the target site.
What is physiological antagonism?
The interaction of two drugs whose opposing actions cancel each other.
how does reversible competitive antagonism work
antagonism rate of dissociation high- equilibrium rapidly established by addition of agonist. Can displace antagonist because by occupying vacant receptors, agonist reduces rate of association of antagonist- so rate of antagonist dissociation>association, so antagonist occupancy falls
allosteric modulation
receptors have other allosteric binding sites in addition to site where agonists/antagonists bind (orthosteric)
through this binding site drugs can influence receptor function eg changing affinity for agonists or produce a response themselves
