Pharmacokinetic Model

Oral Administration

GIT

F Dose

ka

Systemic
Circulation

(Vd)

k

IV Administration

IV bolus

Dose

Systemic
Circulation

(Vd)

k

  • Dose :  The administered dose, mg

  • F :  The drug bioavailability, no units

  • ka :  The first order absorption rate constant, hour -1

  • Vd :  The volume of distribution, liters

  • k = (CLT/Vd) :  The first order elimination rate constant, hour -1

Model Assumptions:

- The drug is eliminated completely by the liver, i.e. the hepatic clearance is equal to the total body clearance.

- The hepatic blood flow and the liver intrinsic clearance are independent.

- After oral administration, the drug is completely absorbed to the portal circulation and the only cause of incomplete bioavailability is drug metabolism during the first-pass through the liver.

- Drug elimination follows first-order process.

IV Dose Simulation Oral Dose Simulation