L2: Quantitative Aspects of Drug Action

Question 1

What does agonist action depend on?

Answer 1

It’s affinity and efficacy

Question 2

What are partial agonists?

Answer 2

Partial agonists are ligands that bind to the agonist recognition site but trigger a response that is lower than that of a full agonist at the receptor.

Question 3

What is mutually exclusive binding?

Answer 3

Cannot be both bound at the same time

Question 4

What is a dose ratio?

Answer 4

A factor by which concentration [agonist] needs to be multiplied in order to reach the same response without antagonist as in the presence of antagonist.

Question 5

What is Schild analysis? Why do we need it?

Answer 5

Schild regression analysis, based upon the Schild equation is a tool for studying the effects of agonists and antagonists on the response caused by the receptor or on ligand-receptor binding. Applying the Schild equation is the best method of determining whether an antagonist is competitive. One should use a large range of antagonist concentrations and determine full agonist-response curves at each concentrations.

Question 6

How is competitive antagonism determined from a plot?

Answer 6

For competitive antagonism, agonist-response curves show parallel shifts in the presence of increasing antagonist concentrations with no decrease in their maxima

Question 7

Why is Schild analysis so powerful?

Answer 7

The dose-ratio is independent of the agonist used in the assay. This is why Schild analysis is so powerful. No parameter in the Schild Equation is dependent on the agonist