Pharmacology Chapter 5 - Pharmacodynamics

Question 1

Pharmacodynamics - def

Answer 1

Study of biochemical and physiological effects of drug….Basically, the study of what drug does to the body and how that happens.

Question 2

Dose-response relationship (3 things.)

Answer 2

1. Determines the minimum amount of drug that can be used.
2. Determines the maximal response that drug can elicit.
3. Determines how much you need to increase dosage to produce the desired response.

Question 3

Dose response could be ____ vs ____.

Answer 3

Grades vs. all or none.

Question 4

Graded means..

Answer 4

dosage is increased as response becomes larger.

Question 5

All or none means…

Answer 5

response produces only one intensity and cannot be tailored to fit individual.

Question 6

Basic features of dose-response (3 phases.)

Answer 6

Phase 1 - occurs at low doses - curve is flat because response is too low to measure.
Phase 2 - increase in doses elicits increase in response.
Phase 3 - occurs at high dose - higher dose does not increase response. May elicit toxicity.

Question 7

Maximal efficacy - def

Answer 7

largest effect that a drug can produce. One drug may have a greater efficacy than another, no matter how much you give (Demerol vs Talwin.)

Question 8

A drug with high maximal efficacy is/is not always more desirable than a drug with lower efficacy.

Answer 8

IS NOT ALWAYS. We don’t want to give Morphine to treat a headache - that’s what Advil is for!

Question 9

Relative Potency

Answer 9

Refers to the amount of drug we must give to elicit an effect…..also compares two drugs.
A drug that produces greater effect at a lower dose is more potent.

Question 10

Why is Relative Potency important?

Answer 10

Important only when potency is so low that huge doses are required for needed effect (rarely happens.) Like, morphine is not superior to Meperidine.

Question 11

potency of a drug has nothing to do with its maximal efficacy (T/F) ??

Answer 11

True. Drug A & B can be equally effective even though one is more potent.

Question 12

What does the statement “This drug is very potent” mean?

Answer 12

the drug produces powerful effects (does not mean that the drug produces its effects at a low dose.)

Question 13

Receptor - def

Answer 13

Any functional molecule in a cell to which a drug binds to produce its effects.

Question 14

How many receptor kinds are there?

Answer 14

4

Question 15

4 Types of Receptors…

Answer 15

Cell Membrane embedded enzymes, Ligand-gated ion channels, G-protein coupled receptor, transcription factors.

Question 16

Cell membrane embedded enzymes…

Answer 16

Span full width of membrane. Response within seconds. Ligand binding domain is external and catalytic binding region is on the inside of membrane.

Question 17

Ligand-gated ion channels

Answer 17

Span membrane, response extremely fast. Regulates flow of ions in and out of cells. When ligand bind channels open…allowing ions to flow either inward or outward.

Question 18

G-protein coupled receptor systems.

Answer 18

Have three components - the receptor, G protein, effector.
domain is located in a pocket accessible from the cell surface.
Response is rapid.

Question 19

Transcription factors

Answer 19

Found with the cell rather than on the surface.

regulate protein synthesis through RNA synthesis.

Question 20

Some drug interactions Do/Do Not involve binding to receptors.

Answer 20

DO NOT. They act through simple physical or chemical interactions with other small molecules. Examples? Antacids, Antiseptics, Laxatives, etc.

Question 21

Drug can __ or __ normal hormone/neurotransmitter/molecule binding.

Answer 21

Mimic (increase response) or block (decrease response.)

Question 22

Drugs can only ____ or ____ the action of the body’s own regulatory molecules.

Answer 22

Mimic or block.

Question 23

Drugs can/cannot give new functions to the cell.

Answer 23

Cannot

Question 24

Can a drug theoretically be made to alter the rate of any biological process for which receptors exist?

Answer 24

YES.

Question 25

Even though a drug is selective for one receptor, is it possible for that drug to produce nonselective effects?

Answer 25

YES, is a single receptor is responsible for several physiological processes.

Question 26

Selectivity does/does not guarantee safety?

Answer 26

DOES NOT.

Question 27

Simple Occupancy theory - def

Answer 27

Intensity of response to a drug is proportional to the number of receptors occupied by that drug.

Question 28

Maximal response occurs when all available receptors…..___

Answer 28

have been occupied.

Question 29

Modified occupancy theory (two parts.)

Answer 29

Affinity Binding and intrinsic binding.

Question 30

Affinity Binding - def

Answer 30

Strength of the attraction between drug and the receptor. The greater the affinity, the greater the potency. Drugs with low affinity require higher concentrations to bind to receptor.

Question 31

Intrinsic activity - def

Answer 31

ability of a drug to activate its receptor - High intrinsic activity relates to high maximal efficacy. 2 drugs can bind to same # of receptors with different intensities of response.

Question 32

Agonist - def

Answer 32

molecules that activate receptors (mimicry.)

Question 33

Agonist has high….___

Answer 33

high affinity and high intrinsic activity.

Question 34

Antagonists - def

Answer 34

produce effects by preventing receptor activation by endogenous regulatory molecules and drugs. Has high affinity for receptor but NO intrinsic activity.

Question 35

Partial Agonists (Partial Antagonist?)

Answer 35

has moderate intrinsic activity & therefore the maximal effect that a PA can produce is lower than that of a full agonist.

Question 36

ED-50 - def

Answer 36

Effective dose 50. Dose required to produce a defined therapeutic response in 50% of the population = middle of the frequency distribution curve.

Question 37

Therapeutic index -

Answer 37

measure of a drug’s safety. Defined as the ratio of drugs LD50 to its ED50.

Question 38

LD50 - def

Answer 38

dose that is lethal to 50% of the animals treated.

Question 39

A ___ therapeutic index indicated that a drug is unsafe while __ indicates that a drug is relatively safe.

Answer 39

small/large.