1 - Pharmacodynamics

Question 1

What is pharmacodynamics?

What are the key steps in the pharmacodynamic process?

Answer 1

Pharmacodynamics is what the drug does to the body.

Question 2

Answer 2

What happened: He was given a beta-blocker that prevented his beta-agonist (albuterol) from doing its job.

Question 3

Define:

• Receptors
• Ligand
• Second Messenger
• Agonist
• Antagonist

Answer 3

Question 4

Explain the effect of agonists.

Answer 4

Note that the bonds are reversible, so ligands are popping on and off. The presence of an agonist drug, in addition to the physiologic ligand, increases effect.

Question 5

Explain the process / effect of antagonist drugs.

Answer 5

Question 6

Explain Simple and Modified Occupancy Theories.

Answer 6

Simple Occupancy Theory: The more receptors that are occupied, the greater the effect. When all receptors are occupied the effect will not increase.

Modified Occupancy Theory: Helps explain why drugs that target the same receptor may have different levels of effect. See picture.

Affinity = Potency: At the same concentration, a more potent drug is more likely to bind.

Intrinsic Activity = Efficacy (how much of a biologic response is generated on binding. This determines the maximal achievable effect.

Question 7

What two factors determine the relationship between drug dose and effect?

What qualities of a ligand can determine the response of a receptor?

Answer 7