2. We can also calculate the pharmacokinetic parameters kel and V if we know the dose given and the plasma concentrations at two (or more) times after an I.V. bolus administration. This time we could use the equation:
ln Cp = ln Cp0 - kel*t
If Cp2 hours = 4.5 mg/liter and Cp6 hours = 3.7 mg/liter after a 400 mg I.V. bolus dose then:
= - 0.0489 hr- 1
thus kel = 0.0489 hr- 1
Now ln Cp 2 hr = ln Cp0 - kel * t
ln 4.5 = ln Cp0 - 0.0489 x 2
ln Cp0 = 1.504 + 0.098 = 1.602
Copyright 2001 David W.A. Bourne