Lecture 1: Intro to Pharmacodynamics

Question 1

Define the term pharmacodynamics and distinguish pharmacodynamics from pharmacokinetics

Answer 1

• Pharmacodynamics: effects of drugs on the body (drug receptors, dose-response curves, and MODA)
• Pharmacokinetics: effects of the body on drugs (absorption, distribution, metabolism, elimination)

Question 2

A specific molecule in a biological system that plays a regulatory role defines what?

Answer 2

Receptor

Question 3

What kind of curve is typically seen when you plot a drug dose arithmetically?

Answer 3

Hyperbolic

Question 4

What kind of curve do you get when you plot a concentration-effect curve (logarithm of drug vs. response)

Answer 4

Sigmoidal

Question 5

What type of response answers the question: “How much?”

This response typically represents which value within a population or a single subject?

Answer 5

• Graded
• Mean value

Question 6

What type of response is used to examine the frequency of (i.e., number of individuals showing) a response within a large population?

Answer 6

Quantal response

Question 7

What is a Non-cumulative vs. Cumulative quantal dose response curve?

Answer 7

• Non-cumulative: number or % of individuals responding at a dose of a drug and only at that dose
• Cumulative: number or % of individuals responding at a dose of a drug and at ALL doses LOWER than that dose

Question 8

How to calculate therapeutic index (TI)?

What does a higher TI indivate in regards to drug safety?

Answer 8

TI = TD₅₀ / ED₅₀

*Higher the TI the safer the drug

Question 9

The range of doses of a drug or of its concentration on a bodily system that provides for the safe and effective therapy, defines what?

Answer 9

Therapeutic window

Question 10

The ability of a drug to change a receptor function and produce a physiological response upon its binding to a receptor, defines what?

Answer 10

Intrinsic activity

Question 11

Define physiologic antagonism

Answer 11

Occurs between endogenous pathways regulated by different receptors

Question 12

A pharmacologic antagonist that binds agonist binding site and is reversible is considered what type of antagonist?

Answer 12

Competitive; can be displaced from receptor by other drugs

Question 13

A pharmacologic antagonist that binds the agonist binding site and is irreversible is considered what type of antagonist?

Answer 13

Noncompetitive agonist site antagonist

Question 14

List the non-covalent bonds from stongest to weakest.

Answer 14

Ionic > Hydrogen > Hydrophobic > Van der Waals forces

Question 15

How readily and tightly that a drug binds to its receptor describes its what?

Answer 15

Affinity

Question 16

A property of a drug determined by its affinities at various binding sites describes what?

Answer 16

Selectivity

Question 17

(T or F) Antagonists have intrinsic activity?

Answer 17

False

Question 18

Cholestryramine is a bile acid-binding resin that is used for the Tx of hypercholesterolemia. It absorbs aspirin, preventing its absorption in GI tract and antagonizing its effects.

Cholestyramine is an example of what type of antagonist?

Answer 18

Chemical antagonist

*Chemical antagonism: when chemical antagonist makes the other drug unavailable

Question 19

Describe a covalent bond drug receptor interaction

Answer 19

Irreversible; drug removal requires new synthesis of a recptor or enzymatic removal of the drug

Question 20

How do you plot a dose response curve? (i.e., what’s on each axis)

Answer 20

Dose on x axis and drug effect on y axis (hyperbolic curve)

Question 21

What is ED50?

Answer 21

Effective dose: dose of drug that produces 50% of its maximal effect

Question 22

What does a qunatal response require?

Answer 22

Pre-defined response (i.e., death, falling asleep, 10% reduction in BP)

Question 23

What is the parameter that describes affinity?

Answer 23

• Kd = drug concentration at which 50% of the drug receptor binding sites are occupied by the drug; unit used is molar
• Lower Kd = higher affinity

Question 24

What is a full agonist?

Answer 24

• Fully activate receptors
• Produce maximal pharm effect when all receptors occupied
• Maximal intrinsic activity

Question 25

What is an inverse agonist?

Answer 25

• Decrease receptor signaling
• Decrease response at receptors w/ significant level of constitutive receptor activity
• Intrinsic activity is present and related to the inhibition of receptor function

*Inverse agonist would bind and cause low BP, while an antagonist would prevent the agonist from binding, thus preventing high BP

Question 26

What is chemical antagonism?

Answer 26

When the chemical antagonist makes other drug unavailable

Question 27

Describe what competitive antagonism does to the dose response curve?

Answer 27

Increases EC50, but does NOT change Emax

Question 28

Describe what non-competitive antagonism does to the dose response curve?

Answer 28

Decreases Emax but does NOT change EC50

Question 29

What is drug efficacy and how is it represented?

What happens when the value representing it increases?

Answer 29

• Maximal pharmacological effect that a drug can produce; represented by Emax
• Greater the Emax, the more efficacious the drug
• Efficacy is related to the total number of receptors available to bind a drug
• Determines clinical effectiveness

Question 30

What is drug potency and how is it represented?

Answer 30

• Amount of drug required to produce a specific pharm effect
• Represented by the ED50
• The lower the ED50, the more potent the drug