Michaelis-Menten kinetics

The rate of drug metabolism via a single metabolic pathway is:

Rate =

Vmax Cp

Km + Cp
Vmax
Km

Vmax

2
Theoretically, all metabolic pathways can
be saturated at very high drug conc.
However saturable drug metabolism is of
great clinical importance when saturation
happens after administration of
therapeutic doses.

Vmax is the maximum rate of drug metabolism (amount/time, or conc/time)

Km is the M.M. constant and it is equal to the drug conc when the rate of drug metabolism is half Vmax (amount/volume)

This hyperbolic relationship indicates that as the drug conc increases the rate of drug metabolism increases until it reaches a plateau at very high drug conc. At this plateau the enzyme system is saturated and the metabolic rate is at its maximum value.