Chapter 14 - Loading Dosing

Question 1

the dosing interval recommended by the manufacturer is based on….

Answer 1

the rate constant of elimination of the drug

Question 2

give an example of when giving a loading dose is recommended

Answer 2

if the time for the drug to reach steady state in the body represents an unacceptable delay

ie - if pt has a serious illness/drugs with a long half life

Question 3

2 other names for the loading dose

Answer 3

priming dose
initial dose

Question 4

true or false

the loading dose is LEAST USEFUL in cases where the therapeutic plasma range of a drug is known

Answer 4

FALSE - this is when loading dose is most useful - we know what we need to get to

Question 5

true or false

giving a loading dose reduces the time of drug onset

Answer 5

true

steady state conc achieved right at the start of treatment

Question 6

true or false

the size of the loading dose is not always larger than the maintenance dose

Answer 6

FALSE - it is

Question 7

the SIZE of the loading dose depends on what?

Answer 7

the dosing interval of the maintenance dose

Question 8

the concentration of steady state depends on what? (HINT - JUST LOOK AT THE FORMULA)

Answer 8

the rate constant of elimination (K)/t 1/2

Co (conc of drug in plasma right after administration of maintenance dose)

tau (the dosing interval)

Question 9

TRUE OR FALSE

in linear pharmacokinetics, the Co is not directly proportional to the size of the dose

Answer 9

false - it is

Question 10

-K does not change
-dose does not change
-dosing interval (tau) does not change

then what does the time to reach Css depend on?

Answer 10

the rate constant of elimination (therefore the half life)

Question 11

true or false

the dose was reduced by 25%. therefore, Co will also reduce by 25%

Answer 11

true

Question 12

if dosing interval = biological half life, the time to reach Css will be approximately _________ half lives of the drug

Answer 12

7 or 8

Question 13

a drug has a half life of 6 hours and the dosing interval is also 6 hours

around when will the drug reach steady state concentration?

Answer 13

2 days

Question 14

true or false

if the dose is SMALL, there will be more fluctuation in the plasma profile between cmax and cmin

Answer 14

false - less fluctuation

Question 15

the size of the loading dose needed to achieve steady state can be calculated based on either the ____ or ____

Answer 15

cmax ss or cminss

Question 16

true or false

drugs with a SHORT HALF LIFE reach a steady state FASTER than drugs with a long half life

Answer 16

true

Question 17

true or false

time to reach steady state is independent of half life

Answer 17

FALSE - dependent

Question 18

the purpose of the loading dose is to attain maximum concentration of _______ as soon as treatment is initiated

Answer 18

Cmaxss

Question 19

in giving a loading dose, the goal is for ____ to = ______

Answer 19

Co to equal cmaxSS

Question 20

symbol for loading dose

Answer 20

D*

Question 21

loading dose is a function of what 3 things

Answer 21

D
the maintenance dose
persistence factor (e-kt)

Question 21

true or false

before we can determine loading dose, we need to know the maintenance dose

Answer 21

true

Question 22

the size of loading dose depends on what 3 things

Answer 22

maintenance dose
elimination rate constant (therefore, half life)
dosing interval

Question 23

if we dont change the drug and given to the same patient, is the k constant?

Answer 23

YES

therefore, when calculating loading dose, we really only can play around with the maintenance dose and the dosing interval

Question 24

true or false as the dosing interval (tau) increases and the dose and K stay the same, the loading dose will decrease

Answer 24

TRUE

Question 25

true or false we can only base the loading dose on CmaxSS

Answer 25

false - can base on CminSS also

Question 26

true or false as dosing interval decreases, loading dose increases

Answer 26

true

Question 27

as the dosing interval decreases, what happens to accumulation factor and persistence factor? what about loss factor?

Answer 27

as the dosing gets more frequent, the accumulation factor and persistence factor increase and the loss factor decreases

Question 28

when will the loading dose be exactly 2x the maintenance dose

Answer 28

when the dosing interval = the half life

Question 29

if tau is smaller than half life, we need a larger loading dose explain this

Answer 29

the drug is administered more frequently and thus accumulates more and there are HIGH PLASMA LEVELS need a very high loading dose to achieve these levels

Question 30

true or false just like for IV, the calculation of EV loading dose also depends on the CminSS or CmaxSS

Answer 30

true

Question 31

B depends on what 5 things

Answer 31

D F Vd Ka K

Question 32

tmax is a function of __ and ___

Answer 32

Ka and K

Question 33

adding the factor "G" (Ka tau) to the EV formula to calculate loading dose accounts for what?

Answer 33

the delay in drug accumulation due to absorptive phase