Lecture 17 : Principles of Pharmacology 2

Question 1

Competitive Antagonists

Answer 1

Bind REVERSIBLY to the same site as the agonist, so compete with agonist.

Effects of this can be overcome by increasing conc of agonist. it is SURMOUNTABLE.

maximal effect still possible

Question 2

Non-competitive antagonists

Answer 2

Bind irreversibly to an allosteric site, reducing maximal response of agonist.

Effects cannot be overcome by agonist, INSURMOUNTABLE.

Question 3

Partial agonists can behave like antagonists…

Answer 3

Question 4

Concentration Ratio definition

Answer 4

Concentration of agonist producing specified response (like EC50) in PRESENCE OF ANTAGONIST

:

Concentration producing same response in absense of antagonist.

Question 5

Allosteric Modulators

Answer 5

Ligands binding to distinct allosteric site on receptor. Either increases or decreases desired product

Question 6

Negative Allosteric Modulators

Answer 6

Question 7

Positive Allosteric Modulators

Answer 7

Question 8

Example Positive Allosteric Receptor

Answer 8

Question 9

Example of an allosteric antagonist

Answer 9

Question 10

Question 11

What are channel blockers

Answer 11

Bind inside channel to prevent passage of ions

Enhanced by receptor activation

Eg. Phencyclidine (PCP) at NDMA receptor

Question 12

Physiological antagonists

Answer 12

Produce opposite effect on tissue

Eg. ACh and adrenaline at heart

Question 13

Desensitisation

Answer 13