Exam1Lec5Pharmacokinetics

Question 1

As the concentration of a drug in contact with a tissue increases, what happens the magnitude of effect

Answer 1

Increases

Question 2

What is EC 50 of a drug?

Answer 2

The concentration that produces one half the maximum efffect (Emax/2)

Question 3

What does EC50 compare?

Answer 3

Potency of drug (x-axis) and Efficacy ( y-axis) of drugs with SAME RECEPTOR.

If the drug needs less concentration for same EC50=incr poteneny

Question 4

What is KD?

Answer 4

Binding of the drug to a receptor. The KD of a drug is the concentration that produces one-half the maximum binding

Question 5

The EC50 value for a response is often ____ than the Kd value, since there is often ____ between occupancy

Answer 5

smaller, amplification

Kd>EC50 b/c of amplification

Question 6

What is an agonist?

Answer 6

Drug or ligand that binds to the same site as the endogenous ligand and produces a signal.

Question 7

Agonsits can be ____ agonists or ____ agonists.

Answer 7

Full, partial

Question 8

Full agonists have affinity for what?

Answer 8

Only for active state

Question 9

Partial agonists have affinity for what?

Answer 9

Higher affinity only for active than inactive state. You wont reach 100%

still can bind to inactive state,
more than 50% effect but less than 100%

Question 10

A ____ agonist can produce the greatest maximal response while the ____ agonsist produces a response that is less than a full agonist.

Answer 10

full, partial

Question 11

What is potency?

Answer 11

Measurement of the amount of a drug needed to produce a given effect. It is used to differentiate between a series of compounds by comparing EC50 values

Question 12

What would the most effacacious agonist do?

Answer 12

It would be the drug can produce the greatest maximum effect

ex: morphine is more effacacious than codeine

Question 13

What is an antagonist?

Answer 13

A drug that binds to the site used by the endogenous ligand (or separate sire) and diminishes or blocks the signal produces by the endogenous ligand.

these inhibit the action of the agonst or receptor

Question 14

Do antagonists initiate a response on their own?

Answer 14

NO AND IT DOESN’T CHANGE EQULIBRIUM OF ACTIVE TO INACTIVE

Question 15

Are competitive antagonists reversible or irreversable?

Answer 15

reversible. You can incr the concentration of the agonist to overcome the antagonist to get the full effect. (on a graph, you see the sigmoidal curve shift to the right and its still reaching max effect)

compete for same binding site and whoever is at higher concentration dominates

Question 16

Are non-competitive antagonists reversible or irreversable?

Answer 16

Irreversible, so it prevents the agonists, at any concentration from producing a maximum effect on a given receptor (on a graph, you see the sigmoidal curve move down)

Question 17

What are inverse agonists?

Answer 17

Reduce the constitutive activity of a receptor

shifts the equilibrium to inactive state =decr.

Question 18

What do inverse agonists have affinity for?

Answer 18

Only for inactive state and they shift equilibrium

Question 19

What does continued stimulation of a receptor with its agonist result in?

Answer 19

A state of desensitization such that the effect that follows continued ot subsequent exposure to the same concentration drug is diminished.

Question 20

What is an example of desensitization?

Answer 20

Attenuated response to the repeated use of beta-adrenergic agonits as branchodialtors for treatment if asthma.

also note for exapple that after you become desensitized, when you stop the drug, after some time, the effect of the drug incr again when taken again after stopping it

Question 21

What happens to the number of receptors with continous or repeated exposure to an AGONIST?

Answer 21

decr the number of receptors

Question 22

What happens to the number of receptors with continous or repeates exposure to an ANTAGONIST?

Answer 22

Incr the number of receptors.

Question 23

Receptor desensitization and down regulation is often responsible for what?

Answer 23

Pharmacodynamic tolerance

Question 24

What is pharmacodynamic tolerance?

Answer 24

Incr doses of drug are required to produce a given magnitude of effect. Also known as tachyphylaxis

Question 25

Explain the concept of spare receptors?

Answer 25

A maximal apparent effect is achieved when a relatively small fraction of the receptors are occupied.

-Max effect with low number of receptors.
-more rececptors=more chance agonist will bind=full effect without occupying more receptors

Question 26

What does the quantal dose-effect curve plot?

Answer 26

The number (percent) of indiv responding to the drug against dosage.

Question 27

What is ED50 ?

Answer 27

Median effective dose
The median effective dose that causes 50% of individuals to respond.

gives us our therapeutic dose

Question 28

What is TD50?

Answer 28

Median toxic dose
The dose that produces a toxic effect in 50% of individuals

Question 29

What is LD50?

Answer 29

Medial lethal dose

The median lethal dose that kills 50% if the tested animals

Question 30

Therapeutic index fomula

Answer 30

Therapeutic index=TD50/ED50

LD/ED for animals

Question 31

For a drug to be safe what ratio do you want of TD50 and ED50?

Answer 31

High TD50 and Low ED50 so you can get a LARGE therapuetic index

Question 32

Which is better
TD 50=10 and ED 50=1
OR
TD50=5 and ED50=2

Answer 32

TD 50=10 and ED 50=1