PK of IV Infusion

Question 1

1 mg/hr to mg/min

Answer 1

0.0167 mg/min

Question 2

1 mg/hr to mcg/min

Answer 2

16.7 mcg/min

Question 3

1 mg/L to mcg/ml

Answer 3

1 mcg/ml

Question 4

1 L/hr to ml/min

Answer 4

16.7 ml/min

Question 5

steady-state

Answer 5

rate in = rate out

Question 6

Rate in

Answer 6

R

Question 7

Rate out

Answer 7

Cl * C

Question 8

when infusion starts

Answer 8

R > Cl * C

Question 9

What happens to elimination rate when you increase concentration?

Answer 9

Increases

Question 10

When you increase the infusion rate, what happens to Css?

Answer 10

Increases

Question 11

If you increase the R, what happens to tss?

Answer 11

it doesn’t change because tss is only impacted by half-life

Question 12

when is Css achieved?

Answer 12

3.3 t1/2

Question 13

Which formula do you use when choosing the bigger R method for reaching the targeted Css?

Answer 13

R=Cl* C / (1-e^-kt)

Question 14

Continuous infusion before s-s

Two concepts/formulas

Answer 14

1) rate in > rate out
2) C = Css (1-e^-kt)

Question 15

At s-s, which formula do we use?

Answer 15

1) rate in = rate out
2) R=Cl*Css

Question 16

Stopped infusion

concept/formulas

Answer 16

1) rate in = 0
2) C = Css * e^-kt
3) DL=Css * V

Question 17

1t1/2

Answer 17

50% Css

Question 18

2 t1/2

Answer 18

75% Css

Question 19

3 t1/2

Answer 19

87.5% Css

Question 20

3.3 t1/2

Answer 20

90% Css

Question 21

What does being at steady-state mean?

Answer 21

rate of drug infused is equal to rate of drug eliminated

Question 22

what are the units of R?

Answer 22

mg/hr

Question 23

Why do we say that drug input is independent?

Answer 23

the concentration of the drug in the body does not affect the rate of administration

Question 24

formula for the time required to reach fraction x

Answer 24

tx = -1.44 * t1/2 * ln(1-x)

Question 25

time to steady-state is only determined by

Answer 25

t1/2 which is 3.3 t1/2

Question 26

t1/2 is only determined by

Answer 26

clearance and volume

Question 27

clearance is only determined by

Answer 27

clearance hepatic and clearance renal

Question 28

Vd is only determined

Answer 28

1. body weight for most drugs
2. fraction unbound for drugs with a high Vd

Question 29

if t > 3.3 t1/2

which formula do we apply?

Answer 29

Apply the C after stopping formula and use Css instead of C when stopped

Question 30

For IV bolus, we can say that C0 is equal to

Answer 30

Css

Question 31

When it takes too long to reach Css on the R we have chosen, what are the two options we can use?

Answer 31

1. Choose a bigger R
2. Give a bolus dose