Plasma conc-time profile

a- After a single iv bolus dose

Assuming that drug elimination is via a single metabolic pathway that follows Michaelis-Menten kinetics:

iv

A

Vmax Cp

Km + Cp

-dA

dt =

Vmax Cp

Km + Cp

The rate of decline of the drug amount in the body is equal to the rate of metabolism.

Integration cannot give an explicit expression for the conc vs. time relationship.

Cp = Cp0 + Km In(Cp0/Cp) - Vmax t/Vd

This expression cannot be used to calculate the plasma conc at any time (t) after drug administration.