Dosing Regimens

Question 1

What is the goal of dosing regimens?

Answer 1

to achieve and/or maintain a therapeutic concentration while avoiding toxicity

Question 2

What are different type of dosing regimens?

Answer 2

• single dose (bolus)
• continuous infusion
• intermittent dosing (fixed-dose/fixed time)

Question 3

Toxicity can be manifested as what?

Answer 3

side effects

Question 4

What does this describe:
- plasma levels increase as drug distributes until the peak is reached
- levels fall due to metabolism and elimination

Answer 4

single dose

Question 5

When you give an IV, when will you see the max peak of concentration?

Answer 5

right after you administer the drug

Question 6

In a single oral dose, what happens?

Answer 6

• you take it once
• after period of time, it reaches its peak
• tapers off over time

Question 7

In a single IV dose, what happens?

Answer 7

• max concentration occurs at time it is given
• tapers off over time

Question 8

What is the goal of intermittent dosing?

Answer 8

to achieve a steady-state concentration

Question 9

How can intermittent doses be given?

Answer 9

oral or IV

Question 10

How many half-lives does it take to achieve steady-state?

Answer 10

5 half lives
(90% steady-state is 3.3 half-lives)

Question 11

Where might you see side effects/toxic effects of an intermittent dose?

Answer 11

at the peaks

Question 12

What is the lowest point on concentration before the next dose in an intermittent dose?

Answer 12

trough

Question 13

What is an example of intermittent doses?

Answer 13

blood pressure medication - given continuously, patient reaches a steady-state if they are taking it correctly

Question 14

If we cannot wait 5 half-lives to reach a steady-state, what can we give patients?

Answer 14

loading dose

Question 15

What is the goal of loading dose?

Answer 15

to achieve a target blood level quickly

Question 16

What types of drugs are beneficial to use loading dose?

Answer 16

• long half-life drugs
• immediate effect is needed

Question 17

What describes when a large initial dose followed by maintenance doses to maintain therapeutic blood levels?

Answer 17

loading dose

Question 18

Does loading dose get a patient to steady-state?

Answer 18

no, it isn’t taken continuously

Question 19

What is not effective if plasma concentration is independent of efficacy?

Answer 19

loading dose

Question 20

When will you reach a steady-state?

Answer 20

after 3.3 half-lives

Question 21

why is there more potential for side effects if intermittent dosing is every 24 hours?

Answer 21

dose is higher

Question 22

Can you increase the rate of a continuous IV infusion to get to steady-state faster?

Answer 22

no, its always after 3.3 half lives

Question 23

If there is a longer timeframe between doses of a drug, what happens?

Answer 23

higher dose is given

Question 24

Increasing rate of drug will increase what?

Answer 24

concentration of the steady state, but WILL NOT effect time to get to steady-state

Question 25

We expect to see the effect of the drug in who?

Answer 25

most people most of the time "most people" = young, middle aged adults

Question 26

Drugs are rarely studied in who?

Answer 26

children and elderly

Question 27

What should be made with respect to the results seen in the individual regardless of what is seen in the population?

Answer 27

clinical monitoring and adjustments

Question 28

What is a standard curve showing how concentration changes over time after oral administration of a drug?

Answer 28

concentration vs time curve

Question 29

What is AUC?

Answer 29

area under the curve

Question 30

What measures the total exposure to drug after a dose?

Answer 30

area under the curve

Question 31

Drugs/total drug exposure can be what % off under the curve?

Answer 31

20%

Question 32

What is Cmax?

Answer 32

maximum concentration of drug/peak effect of drug you will get

Question 33

What is MEC?

Answer 33

minimum effective concentration (concentration needed to see a minimum effect)

Question 34

What is tmax?

Answer 34

time it takes to reach maximum concentration

Question 35

What is the lag period?

Answer 35

period of time after administration where it is not working

Question 36

What can be the same for IV, oral, and extended release drugs?

Answer 36

area under the curve

Question 37

What is used to demonstrate the expected response to a given dose of a drug?

Answer 37

dose-response curve

Question 38

What includes the range of concentrations needed to demonstrate a relationship is so great a semi-log plot is used rather than the linear format?

Answer 38

dose-response curve

Question 39

Linear formatted dose-response curves are hard to determine what?

Answer 39

different concentrated, so log plots are used to get a better range of concentration

Question 40

What is the dose required to produce a response?

Answer 40

potency

Question 41

What does potency of a drug depend on?

Answer 41

its affinity

Question 42

What describes the strength of binding between a receptor and its substrate (how much does the drug like the receptor)?

Answer 42

affinity

Question 43

What is measured by Kd (equilibrium dissociated constant)?

Answer 43

affinity

Question 44

What does a high Kd value mean?

Answer 44

low affinity, so strength of binding between receptor and substrate is decreased, so potency is decreased (will take longer to reach desired efficacy)

Question 45

What does a low Kd value mean?

Answer 45

high affinity, so strength of binding between receptor and substrate is increased, there will be a stronger response, and potency will increase

Question 46

Two drugs do the same thing, but one requires 5 mg to be effective (drug A), and the other requires 20 mg to reach same effectiveness (drug B), which is more potent?

Answer 46

Drug A

Question 47

What is EC50?

Answer 47

concentration of drug that produces half the maximal effect

Question 48

What is used to identify the relative potency of a drug?

Answer 48

EC50

Question 49

What is helpful in comparing potencies of drugs that are designed to produce the same effect?

Answer 49

EC50

Question 50

How is EC50 determined?

Answer 50

in a test tube (in-vitro comparison)

Question 51

What is described as the maximum effect a drug is capable of producing (how much of an effect after drug binding)?

Answer 51

efficacy

Question 52

What is described as the degree to which a response is achieved?

Answer 52

activity

Question 53

What is Emax?

Answer 53

maximal effect of drug