Pharmacokinetic parameter determination and dosage recommendation

Assumptions:

1- Assume a single Michaelis-Menten elimination pathway.

2- Assume steady state plasma conc with repeated administration of a fixed dose.

3- Two different steady state conc during administration of two different doses.

A - Mathematical method

The relationship that relates the administered dose and the steady state conc is:

FD

τ
=

Vmax Cpss

Km + Cpss

When two different steady state conc are determined while administration of two different doses, two different equations can be constructed:

FD 1

τ
=

Vmax Cpss 1

Km + Cpss 1
   and   

FD 2

τ
=

Vmax Cpss 2

Km + Cpss 2

These two equations can be solved simultaneously to determine the two unknown pharmacokinetic parameters Vmax and Km.