Agonists/Antagonists Flashcards
(18 cards)
What are partial agonists?
Drugs whose maximum response is less than the full response the tissue is capable of
What proportion of receptors do partial agonists occupy to evoke a maximum response?
Occupy all receptors to evoke their maximum response
Describe the efficacy of partial agonists
Low
What configurations are receptors in mostly with partial agonists?
Inactive configurations
Describe the magnitude of response for partial agonists
Reduced
What are the EC50 values compared to Kd values like for partial agonists?
EC50 values close to Kd values
How does efficacy explain how partial agonists can occur?
Efficacy explains how response is not linearly proportional to receptor occupation
What is the “e” (intrinsic efficacy) of a full agonist?
1 (full response tissue capable of)
What is the “e” (intrinsic efficacy) of a partial agonist?
1 > e < 0
Do partial agonists have any receptor reserve?
No
What is the “e” (intrinsic efficacy) of an antagonist?
0
What is the “e” symbol for intrinsic efficacy also known as?
An epsilon
How is the drug response curve that a partial agonist produces similar to that of a full agonist?
Both the same shape - sigmoidal
Why do both partial agonists and full agonists produce the same curve shape?
Once binding has occurred = same process as full agonist, so same shape
How is the drug response curve that a partial agonist produces different to that of a full agonist? (2)
- Clear reduced max
- More rightward displacement of curve
Why are there differences in the drug response curve that a partial agonist compared to that of a full agonist?
Epsilon for intrinsic efficacy in partial agonist lower
What is the same with partial agonists and full agonists? (2)
- Receptor number
- Binding affinity (kd)
Can full and partial agonists be equipotent? Why?
Yes, as full/partial agonism only accounts for efficacy
