Lecture 9 - How to drugs work: Receptors and agonists

Question 1

Describe the importance of receptor binding in drug action

Answer 1

a. Plays a crucial role in specificity, efficacy, safety and development pf pharmaceutical agents
b. It is through receptor interactions that drugs are able to exert their therapeutic effects whilst minimising side effects and ensuring the selectivity of their actions

Question 2

What are the features of mass action in relation to receptor occupancy?

Answer 2

Mass action in receptor occupancy describes the direct and proportional relationship between the concentration of a drug and its binding to receptors, leading to a corresponding pharmacological response.

Question 3

What is potency and how is it measured?

Answer 3

a. Potency refers to the strength or effectiveness of a drug in producing a specific biological response or effect at a given concentration/dose.
b. Potency is not only dependent on affinity
c. Potency is typically measured using two parameters:
i. Effective concentration 50%
ii. Effective dose 50%

Question 4

Binding curve summary

Answer 4

a. Binding curve is sigmoid
b. High drug concentration may occupy all receptors
c. Half Rtot occupied when drug concentration = Ka
d. “location” of concentration vs occupancy curve is dependent on drug receptor affinity
e. Curves shift to the left = higher affinity (lower Ka but higher pKa)

Question 5

What are the factors that determine drug potency?

Answer 5

a. Affinity for the receptor
b. Efficacy
c. Drug-receptor interaction
d. Route of administration
e. Metabolism

Question 6

Describe the concept of intrinsic efficacy

Answer 6

a. Describes a drug’s ability to activate a receptor and produce a biological response
b. The stimulus generated upon receptor binding

Question 7

Why are tissue responses to drugs dependent on receptor expression?

Answer 7

Because receptors serve as the molecular targets that drugs interact with to produce their effects.