Pharmacodynamics

Question 1

Define pharmacodynamics.

Answer 1

Pharmacodynamics is the term used to describe the effects of a drug on the body, which are usually described in quantitative terms.

Question 2

How can the binding of a drug to a receptor be plotted?

Answer 2

Drug-receptor binding curves

Question 3

How can the pharmacodynamics of a drug be quantified?

Answer 3

By looking at the relationship between the dose (concentration) and the organism’s/patient’s response to that drug. The two major types of dose-response relationships are graded and quantal. These can be plotted in dose-response curves.

Question 4

What is the difference between a graded and quantal dose-response relationship?

Answer 4

• Graded: describe the effects of various doses of a drug on an individual.
• Quantal: show the effects of various doses of a drug on a population of individuals.

Question 5

What types of responses can be quantified using a quantal dose-response curve?

Answer 5

• Median effective dose (ED50)
• Median toxic dose (TD50)
• Median lethal dose (LD50)

Question 6

Define therapeutic window.

Answer 6

The therapeutic window is the range of doses (concentrations) of a drug that elicits a therapeutic response, without unacceptable adverse effects (toxicity), in a population of patients. The therapeutic window can be quantified by the therapeutic index (TI): TI = TD50/ED50