Half-Life Flashcards
1
Q
What is half life?
A
time taken for the plasma concentration to fall by half.
2
Q
Elimination rate constant
A
Concentration at various times = [initial] x logkt
kt being elimination rate constant
Expresses the proportion of drug eliminated per unit time
3
Q
What is the formula for half life
A
Half life = 0.693 x Vof D/ Clearance
4
Q
What affects half life
A
Increased by
Increase VofD
Decreased clearance
5
Q
What does half life determine?
3 things
A
The duration of action after a single dose
The time require to reach steady state with chronic dosing - it takes 3-5 half lives
The dosing frequency required to avoid too large fluctuations in plasma concentration
