Week 2 - Receptor Theory

Question 1

What is a receptor?

Answer 1

a macromolecule with a binding site for chemical molecules, which causes a change in cell function

Question 2

What is the Hill equation?

Answer 2

[AR]= [A] / K_A + [A]

Question 3

Why is a higher affinity of a drug to their receptor preferred?

Answer 3

• lower amounts of the drug will be required
• lower likelihood of the drug interacting with other receptors
• fewer side effects

Question 4

What is intrinsic activity?

Answer 4

• represented by α
• used to compare compunds which act through the same receptor but with different maximum responses
• E_max of test agonist / E_max of full agonist
• full agonist is 1
• partial agonist is between 0 and 1
• antagonist is 0

Question 5

What is constitutive activity?

Answer 5

• receptor is activated without the presence of an agonist stimulating it
• spontaneously switches between active and inactive forms

Question 6

What are the types of antagonism that don’t involve the receptor?

Answer 6

Chemical: combines and neutralises the substance
Functional/ physiological: opposite effect of the agonist to counteract it
Pharmacokinetic: drug that accelerates metabolism or elimination of the agonist
Indirect: acts on a downstream receptor that is linked to the agonist’s final response

Question 7

What are the types of antagonism that involve the receptor?

Answer 7

• compete for the binding site reversibly / irreversibly
• bind to adjacent site that overlaps with binding site
• bind to allosteric site at the same time as agonist to influence binding / effect of agonist