Antagonists

Question 1

Define antagonists.

Answer 1

Drugs which bind to the receptor and block the action of endogenous regulatory molecules.

Question 2

Describe reversible antagonists including effect on dose-response curve

Answer 2

Can be displaced by an excess of agonist, shifts dose response curve to the right

Question 3

Describe irreversible antagonists including effect on dose-response curve.

Answer 3

Bind the receptor covalently, lowers curve to degree of bound antagonist.

Question 4

Describe competitive antagonists including effect on dose-response curve.

Answer 4

Binds to same site as agonist (in competition) maximum effect unchanged but agonist dose required is increased.

Question 5

Describe competitive antagonists including effect on dose-response curve.

Answer 5

Binds to same site as agonist (in competition) maximum effect unchanged but agonist dose required is increased.

Question 6

Describe non-competitive antagonists including effect on dose-response curve.

Answer 6

Binds to a different site on agonist, reversible, cannot be overcome by increasing [agonist]. Emax is reduced

Question 7

Explain population studies for “all or none” responses.

Answer 7

Studies done to determine effective and lethal doses of drugs to determine general safety vs efficacy.

Question 8

Define therapeutic index.

Answer 8

= LD50/ED50

-A drug with a narrow TI has a narrow margin of safety

-A drug with a wide TI has a wide margin of safety