M&R Drugs And Receptors Flashcards
What is the most critical factor in determining drug action?
Concentration or drug molecules around a receptor
How do drugs exert their effect?
By binding to a target (mostly proteins)
How do you work out molarity?
Mwt
What is the binding of the ligand determined by?
Affinity of the ligand and receptors
What is the receptor activation governed by?
Intrinsic efficacy
What is the difference between intrinsic efficacy and efficacy?
Intrinsic efficacy is the ability to activate a receptor ligand complex whilst efficacy is the ability to generate a response
What do antagonists do?
They prevent the binding of agonists by blocking the sites
What is B max?
The maximum binding capacity of receptors
What is Kd?
The measure of affinity
The concentration of ligand required to occupy 50% of available receptors
What does a low Kd mean?
There is a high affinity for ligands (lower drug conc needed for 50% binding)
What are the scale of most drug graphs?
Logarithmic
What is the shape of the logarithmic curve?
Sigmoidal
What does the concentration response curve show?
The EC50 - gives 50% of max response
This is a measure of potency - affinity + efficacy
How does salbutamol ensure only B2 receptors are stimulated?
B2 selective efficacy
How does salmeterol ensure B2 stimulation?
Selective based on affinity
Why can there be not all receptors binded but still 100% response?
Spare receptors
Why do spare receptors exist?
Amplification in signal transduction
So few moles needed to impact whole cell response
How does spare receptors allow for increased sensitivity?
If 50% occupancy gives full response then the cell is more suspectible to full response with a lower conc of drug
What does changing the receptor number do?
Changes agonist potency and can effect the maximal response
Are receptor numbers fixed?
No, they can be up regulated or down regulated depending on what is required.
What are partial agonists?
Turns receptor on a bit, even with 100% receptor filled gamy get a full response
What are the 3 mechanisms of antagonists?
Reversible competitive
Irreversible competitive
Non competitive
