Volume of Distribution Flashcards
1
Q
Volume of Distribution Definition
Formula
A
Parameter relating total drug in body to plasma concentration
V=Total amount of drug/[plasma]
2
Q
What determines the Volume of Distribution
4 things
A
Binding to tissue
Binding to plasma proteins (higher less VofD)
Molecular weight (higher less VofD)
3
Q
How is it calculated?
A
Use [drug]vs time chart and calculate VofD using starting dose over extrapolated concentration at start of therapy
4
Q
What is the purpose of the VofD?
A
To calculate a loading dose
5
Q
What is the formula of a loading dose
A
Loading dose = Vx [target plasma]
6
Q
Rate of Distribution
A
Determines the onset and offset of drug effect.
For instances the peak effect of digoxin occurs long after the plasma concentration decreases as it redistributes to its site of action
