Pharmacodynamics: DOSE- RESPONSE RELATIONSHIPS

Question 1

Define POTENCY:

Answer 1

A measure of drug activity expressed in terms of amount of drug that produces an effect of given intensity. A drug is considered potent if a small dose produces large biological effect.

Question 2

POTENCY is relatively UNIMPORTANT in clinical use of drugs.
True/False

Answer 2

True

Question 3

With respect to POTENCY, Fentanyl is more potent than meperidine.
T/F

Answer 3

True . At low dose fentanyl is able to evoke the same intensity of response as meperidine will at high concentration.

Question 4

Define EFFICACY:

Answer 4

The ability of a drug to produce effect.

Question 5

Emax is the minimal effect that can be produced by a drug. T/F

Answer 5

False. It is the MAXIMAL effect that a drug can produce.

Question 6

Efficacy is determined mainly by:

Answer 6

Properties of the drug
Receptor-Effector System

Question 7

Efficacy is an important clinical measure.
T/F

Answer 7

True.

Question 8

Potency is a much more important clinical measure than efficacy.
True/False

Answer 8

FALSE! Efficacy is a much more important clinical measure as potency is relatively UNIMPORTANTLY in clinical use of drugs.

Question 9

______ help in estimating the safety of a drug.

Answer 9

Dose- Response Curve

Question 10

Therapeutic Index is given as(it’s formula):

Answer 10

T.I= LD50/ED50
LD50: MEDIAN LETHAL DOSE OF DRUG IN ANIMALS(from slide)

ED50- is the conc. given to 50% of the population to produce clinical effect.
LD50- is the conc. given to 50% of the population to produce toxic/lethal effects.

Question 11

Types of Antagonism:

Answer 11

Pharmacological
Physiological
Chemical

Question 12

Chemical antagonism, it is caused by:

Answer 12

Combination of agonists with antagonists with resulting inactivation of the agonists

Question 13

Example of chemical antagonism:

Answer 13

Binding of Dimercaprol to mercury ion. Dimercaprol is used as an antidote in mercury poisoning.

Question 14

Physiological Antagonism, involves:

Answer 14

An agonist and antagonist acting at two independent sites and inducing independent but opposite effects.

Question 15

Histamine and Adrenaline is an example of physiological antagonism. T/F

Answer 15

True.

Question 16

The type of antagonism involving the action of both the agonist and antagonist on the same site is _______ antagonism

Answer 16

PHARMACOLOGICAL Antagonism

Question 17

Pharmacological Antagonism consists of two types:

Answer 17

Competitive Antagonism
Non-competitive Antagonism

Question 18

Example of non-competitive antagonism is:

Answer 18

Action of epinephrine and Dibenamine

Question 19

Competitive Antagonists include:

Answer 19

Acetylcholine and Atropine

Question 20

Dose-Response Relationship is dependent on a number of factors,namely:

Answer 20

Adsorption of the drug
Metabolism of the drug
Elimination of the drug
The site of action of the drug in the body
Presence of other drugs or disease

Question 21

At relatively LOW doses, the response to a drug generally INCREASES in direct proportion to INCREASE in dose. T/F

Answer 21

True

Question 22

The relationship between the concentration of the drug and the observed effect(response) is graphically represented as a _____ curve

Answer 22

HYPERBOLIC

Question 23

At higher does of a drug, the amount of change in response to an increase in dose gradually decreases until a dose is reached that produces no further increase in the observed response(I.e) plateau).
T/F

Answer 23

True!

Question 24

What is the major factor that controls drug effect?

Answer 24

CONCENTRATION OF THE DRUG AT THE SITE OF ACTION

Question 25

________ is therefore defined as the measurement of the relationship between the quantity/concentration of a substance and it’s overall effect on an organism.

Answer 25

Drug-Response Effect

Question 26

Response against the logarithm of drug concentration gives a _____ dose-response curve.

Answer 26

SIGMOIDAL

Question 27

A steep curve that begins to climb even at a small dose suggests a chemical of _____

Answer 27

HIGH POTENCY

Question 28

The more potent the chemical, the less it takes to kill. T/F

Answer 28

True

Question 29

Types of Dose-Response curve:

Answer 29

Graded dose-response curve
Quantal dose-effect curve

Question 30

Characteristics of Graded D-R curve:

Answer 30

• Measured in a single biological unit
• Continuous scale(increase in dose= increase in effect)
• Relates dose to intensity of effect

Question 31

Characteristics of Quantal Dose-Response:

Answer 31

• Population studies
• all-or-none pharmacological effect
• Relates dose to frequency of effect

Question 32

Potency is often measured at 50% concentration or dose level.
True/ False

Answer 32

True