Exam 2 - Two-Compartment Model: IV Bolus Flashcards
What are the two-compartments?
Central (plasma) & Peripheral (tissue)
In which compartment does elimination occur?
Central (plasma)
Dependent Variables
Cp & Ct
Independent Variable
t
Parameters
Cp0, k12, k21, k10
Drug is administered into which compartment?
Central (plasma)
What are the “transfer” rate constants?
k21, k12, k10
What are the apparent rate constants?
alpha & beta
Vp
volume of the plasma compartment
Vt
volume of the tissue compartment
Vp + Vt
total volume
What is assumed about the apparent rate constants?
beta < alpha
What is the distribution phase effected by?
alpha & beta
What is the elimination phase effected by?
beta only
Vd(ss)
Volume of distribution at steady state
Vd(exp)
Extrapolated volume of distribution
Vd(B)
Volume of distribution by area
Vp equation
Vp = D(0)/(A+B)
Vd(exp) equation
Vd(exp) = D(0)/B
What is Vp used for?
To estimate Cp immediately after the dose
What is Vd(ss) used for?
To describe protein binding effects on distribution
What is Vd (exp) used for?
To estimate drug in the body (D) during the elimination phase
What is Vd(area) closely related to?
Overall CL (based on AUC)
Compare Vd(exp), Vd(area), Vd(ss), & Vp
V(exp) > Vd(area) = Vd (ss) > Vp
t1/2 equation
t1/2 = 0.693/beta
What is the half-life known as in this model?
Terminal half-life
CL equation
CL = D(0)/[AUC]
