Clinical Pharmacokinetics Flashcards
1
Q
define volume of distribution (Vd)
A
- a measure of the apparent space in the body available to contain the drug
- Vd is the volume that would be required to contain all of the drug in the body at the same conc. as it is in the blood
- Vd = amount of drug in body / plasma drug conc.
- units = volume
2
Q
describe high vs low Vd
A
- Low Vd means that most of the drug is in the plasma
- High Vd means that most of the drug is in the extravascular compartments
3
Q
how can Vd be determined?
A
- Vd = Dose/C0
- If we want to achieve a target plasma concentration (TC) quickly, we can calculate the dose required as:
- Dose = Vd x TC
4
Q
define clearance
A
- Clearance is defined as the the volume of blood cleared of drug per unit time (vol/time)
- the rate of drug elimination is directly proportional to the drug concentration
- Rate of elimination = CL x C (drug conc.)
- first-order kinetics