Session 8 - Drugs + Receptors/Pharmacokinetics

Question 1

1 mole of any substance contains how many particles?

Answer 1

6x10^23

Question 2

What is the relationship between molecular weight, grams per litre and molarity?

Answer 2

Molecular weight x Molarity = Grams per litre

Question 3

What is affinity?

Answer 3

The likelihood of a ligand binding to its target

Question 4

What is efficacy?

Answer 4

Likelihood of activation of the receptor

Question 5

In terms of affinity and efficacy which do agonists and antagonists have?

Answer 5

Agonists have both affinity and efficacy

Antagonists have just affinity

Question 6

What is Bmax?

Answer 6

Maximum binding capacity

Question 7

What is Kd?

Answer 7

The dissociation of constant, it is a measure of affinity.

It is the concentration of drug needed for 50% occupancy

Question 8

What does a low Kd value mean?

Answer 8

High affinity

Question 9

How do dose response curves differ from concentration response curves?

Answer 9

Conc response curves used in measuring a response at particular cells/tissues
Dose response curves used in measuring a response in the whole animal

Question 10

What is Emax?

Answer 10

The maximum possible response

Question 11

What is EC50?

Answer 11

Concentration giving 50% of the max response

Question 12

Why does salbutamol have small side effects?

Answer 12

Selective EFFICACY + route of administration limit Beta-1 activation

Question 13

Why does salmeterol have limited side effects?

Answer 13

Very high selective AFFINITY for beta-2 receptors

Question 14

Describe the concept of spare receptors?

Answer 14

In some cases less than 100% occupancy can still result in a 100% response, so there are are spare receptors

Question 15

How are spare receptors useful?

Answer 15

It allows for increased sensitivity, allowing for responses at lower concentrations of agonists

Question 16

What are partial agonists?

Answer 16

Partial agonists cannot produce a maximum response even at at 100% occupancy

Question 17

Name the partial agonist involved in morphine addiction

And how does it work?

Answer 17

Buprenorphine
It has a higher affinity for the opioid receptors than morphine, but a lower efficacy. This means it out-competes morphine for the receptors and provides sufficient pain relief but causes less respiratory depression than morphine

Question 18

Name the three types of antagonists

Answer 18

Reversible competitive
Irreversible competitive
Non-competitive

Question 19

List some of the main drug targets

Answer 19

• Enzymes (47%)
• GPCR’s (30%)
• Ion channels (7%)
• Transporters (4%)
• Nuclear hormone receptors (4%)