S9 Pharmacodynamics Flashcards
What is a ligand?
Can be endogenous or exogenous.
A molecule that binds to a receptor and acts as an agonist or antagonist.
What is the definition of affinity?
Ability of a ligand to bind to a receptor - how strongly a ligand binds to a receptor
What is efficacy?
The ability to cause a measurable response (activate a receptor and produce a biological response)
What is intrinsic efficacy?
The ability to activate the receptor
What is an agonist?
A ligand that activates a receptor
What is an antagonist?
Ligand that binds to the receptor and blocks the binding site of an endogenous agonist
What is potency?
The dose of drug needed to produce a certain level of response
What is EC50
The concentration of drug that gives 50% of the maximal response
What is a partial agonist?
Agonists that only have partial efficacy (a partial response)
What is intrinsic activity?
The maximal response
What is functional antagonism?
The use of antagonists to prevent something from happening
What is reversible competitive antagonism?
Most common and important.
Relies on a dynamic equilibrium between ligands and receptors.
The more antagonist added, the greater the inhibition.
The more agonist, less antagonist binds - the inhibition is surmountable
What is irreversible competitive antagonism?
When the antagonist dissociates slowly/not at all
As the antagonist concentration increases and time increases, more receptors are blocked - non-surmountable
What is non-competitive antagonism?
Antagonist binds to allosteric site and the endogenous ligand binds to the orthosteric site
No competition
What do spare receptors do?
They increase sensitivity/potency - allows responses to occur at lower concentrations of agonist
