Pharmacodynamics Flashcards
What are GPCRs regulated by
Light, odorants, hormones, neurotransmitters, ions
What is a ligand
Something that binds to a receptor.
E.g drug, hormone, neurotransmitter
What does it mean if a drug binds reversibly to receptors
Binding governed by association and dissociation
What does a antagonist do
Block the binding of an endogenous agonist
What does a agonist do
activate a receptor
What’s the difference between agonists and antagonists
Antagonists only have affinity whereas agonists have affinity and intrinsic efficacy
What is intrinsic efficacy
Ability of receptor to be converted into active state
Can change confirmation of receptor
What is clinical efficacy
Indication of how well a treatment succeeds in achieving its aim.
How do we measure binding of receptors and ligands
By binding of radioactively labelled ligand to cells/ membranes prepared from cells.
You incubate the radioligand and receptor.
What is Kd
Concentration of ligand required to occupy 50% of the available receptors.
Index of Affinity
Lower the Kd the higher the affinity
Lower conc required to occupy receptors the higher the affinity.
What is EC50
Drug potency
Effective concentration giving 50% of your maximal response
What does potency depend on
Affinity
Intrinsic efficacy
Also cell/ tissue-specific components
Why can less than 100% occupancy lead to 100% response
There are spare receptors
Why have spare receptors
Increase sensitivity/potency allowing responses at low conc of agonist
Difference between full agonist and partial agonist
Partial agonist has no spare receptors so insufficient intrinsic efficacy for maximal response.
