L15 - Receptor Agonists - Inducing A Response Flashcards
What is an agonist?
Ligands that activate the receptor
= drives the response
What is affinity in terms of response?
How well a drug binds to a receptor
- receptor occupancy
What is efficacy in terms of response?
How well a drug activates a receptor
- receptor activation
How to measure response: the conc response curve:
- biological system exposed to inc conc of agonist
- chosen response recorded
- plot against conc on log scale
What are the 3 different parts of the response curve?
- initial low conc evoke limited response (low receptor occupancy, poor response)
- inc conc = inc response in linear fashion
- response is maxed out (full receptor occupancy, max bio response)
What is Emax?
Maximum effect produced by an agonist
- how effective the agonist is at producing a response
What is EC50? What is it a useful measure for?
Conc of agonist require to elicit 50% of max response (Emax)
- compare between different agonists in same system
How can drugs/agonists be compared?
Using response from the same biological system
- compare profile of con response curves, Emax and EC50
What happens if agonist A and B have same Emax?
Same efficacy
What happens if agonist A and B have different EC50 values?
Different potencies
What is a partial agonist?
Agonist receptor interactions that do not produce a full response in a biological system
What do partial agonists have that make them partial?
- poor affinity - limited receptor occupancy
- poor efficacy - can’t produce full response
What are full agonists?
Agonists that produce a full response
What are inverse agonist?
Agonists that can reduce the activity of a biological system from basal levels
What is biased agonism?
Promotes different activation states of receptors - different 2nd mes = different response
