Pharmacodynamics

Question 1

In what case a partial agonist can behave as an antagonist?

Answer 1

Partial agonist acts in presence or pretreat with full agonist ▶️ former displaces the last from receptor ▶️ ⬇️ response

Question 2

How can you reverse the effect of competitive antagonist? What is impact on the agonist? Effect on the D-R curve.

Answer 2

⬆️ dose of agonist
⬇️ potency of agonist
Shift to the right

Question 3

Could you reverse the effect of no competitive antagonist? Impact on the agonist. Effect on the D-R curve.

Answer 3

Partially reverse by ⬆️ doses of agonist 
⬇️ efficacy (⬇️ maximal response) 
Shift downward (non parallel shift to the right)

Question 4

Effects of potentiation on a agonist. Effect on a D-R curve.

Answer 4

⬆️ potency

Shift to the left

Question 5

How do you expect the therapeutic index (TI) in a “safe” and likely toxic drug?

Answer 5

“Safer drug” ▶️ larger TI

Likely toxic drug (care for interactions too) ▶️ TI

Question 6

How can you reverse a competitive antagonist? Example with BZD.

Answer 6

⬆ concentration of agonist

Competitive Antagonist of Diazepam - flumazenil on GABA receptor

Question 7

No competitive antagonist of norepinephrine. Effect.

Answer 7

Phenoxybenzamine (Alfa blocker)

⬇️ efficacy (not overcome by ⬆️ substrate)

Question 8

Partial agonist of morphine. Which receptors bind?

Answer 8

Buprenorphine

Opioid u-receptors