Pharmacology: Future Therapies

Question 1

Process of Ibuprofen discovery

Question 2

Benefit + disadvantage of drug discovery using animals to test/assay

Answer 2

Benefits

• Physiological inert

Drawbacks

• molecular target = unknown
• clinical studies showed GI side effects

Question 3

Similarities in COX diversity

Question 4

Differences in COX diversity

Question 5

Name 1^st generation COX-2 inhibitors

Answer 5

Nimesulide, Etodolac, Meloxicam, Dup697

Question 6

How did COX-2 inhibitors come about?

Answer 6

Came from animal models looking for potent anti-inflammatory agents with minimal side effects on the stomach

Question 7

What does COX-2 enzyme induce?

Answer 7

Inflammation

Therefore, 1^st generation compounds evaluated against COX-2

Question 8

Structural comparison between COX-2 to COX-1

Answer 8

Crystal structure of enzyme

Larger, more flexible access channel for substrates

Larger inhibitor binding site (25%)

Allowing binding models to be constructed using computers

Question 9

Process of COX-2 inhibitor discovery

Question 10

Benefits + drawbacks of COX-2 inhibitor discovery process

Question 11

Describe 3 strategies in drug discovery

Answer 11

Phenotypic = based on modulation of a cellular phenotype but MOA is unknown e.g. ibuprofen

Target-based = based on inhibiting a known target e.g. COX-2i

(1) Ligand-based = knowledge of candidate molecules

• create pharmacophore model
• define/refine model

(2) Structure-based = knowledge of COX enzyme

• dynamic modelling of target
• in silico screening of compounds

Question 12

Why is it vital for the drug target to be correctly chosen?

Question 13

Explain all strategies to identify potential drug targets

Answer 13

Target validation

• Human genetics information
• Genetic deletion studies
• Gene expression + functional studies in disease relevant cells
• Understand relevant biochemical pathways

Drug Discovery

• Conventional methods
  
  • High throughput screening
  • Structure-based drug discovery
  • Fragment-based drug-discovery
• Natural products

Question 14

Human genetics

• What do mutations lead to?
• Congenital defects?

Answer 14

Human genetics (best model in identifying drug targets)

Mutations lead to human pain axis changes

Congenital defects e.g. Na_v1.7 (good analgesic target)

• Loss of function mutation = decreased pain perception (+vice versa)

Question 15

Genetic deletion

• name targets which have been deleted
• which animal had target deleted to be later studied?

Answer 15

Analgesic target can be deleted from a mouse

Pain-related behaviours of the mouse can be studied

Targets include Nav1.7, Cav2.2, Mu-opioid receptor

Used for target validation

Question 16

Gene expression studies

• what neurones are isolated?

Answer 16

Nociceptive neurones isolated

• Gene expression spectrum monitored (even to individual neurones)
• A strategy is to define spectrum
• Compare it with non-nociceptive neurone
• Selective expression in the nociceptive neurone could be relevant to pain
  
  • Nav1.8 channels
  • P2X3 receptors

Question 17

How can nociceptive neurones be isolated and monitored?

Question 18

How can intracellular calcium concentration be elevated?

Answer 18

Capsaicin activates TRPV1 channel to increase intracellular Ca²⁺

• Investigate capsaicin inhibitors