Clinical Applications of Pharmacokinetics Flashcards Preview

Pulmonary and Renal Physiology > Clinical Applications of Pharmacokinetics > Flashcards

Flashcards in Clinical Applications of Pharmacokinetics Deck (23):
1

Clearance

Cl= rate of elimination/C

2

Slope of the Log C vs T relationship is...

Inverse of Half-life! Steeper slope, shorter half life

3

Vd equation

Vd=A/C

4

T1/2 Equation

T1/2 = (.7xVd)/Cl

5

Vd after distribution is complete

Vd extrap = A / C0extrap

6

Does a higher concentration of free drug increase or decrease Vd?

Increases Vd! More available to move into tissues. This also increases the half life.

7

Css

Steady state concentration that occurs when a drug is infused. This is assuming that nothing happens to change the clearance of the drug.

8

At Css, rate of infusion = _________ .

Rate of elimination.

9

Equation for Css

Css=IR/Cl

10

Does Vd affect css?

No, but a drug with a higher Vd will take longer to reach Css.

11

How long does it take to reach Css?

Generally about 4-5 half lives.

12

How long does it take to get from one Css to a new one?

4-5 more half lives. New Css is reached when infusion rate is increased.

13

How to reach Css without waiting 4-5 half lives?

Loading dose!

14

Correct loading dose equation

Dl = Css * Vd

15

What else do we need to consider for oral administration of a drug?

Bioavailability and rate of absorption

16

How to determine bioavailability (F)?

Compare AUC oral vs AUC IV.

17

Amount of drug entering body after oral administration?

A=Dose * F

18

Clearance equation w/bioavailability

Cl = (D*F)/ AUCoral

19

Slow absorption effect on Cmax and T max

Decreases Cmax, increases Tmax

20

What happens to rate of elimination of average concentration rises?

Rate of elimination increases

21

Does it take more time to remove all of a drug from a previous dose during repeated administration or a single dose?

Single dose

22

Cssav equation

D*F/T*Cl

Where T is the interval between doses.

23

Does slower oral absorption result in larger or smaller peaks and troughs?

Smaller - more even activation.