Nonlinear or capacity limited pharmacokinetics can occur whenever a process involved in the absorption, distribution or elimination of a drug becomes saturated. This model demonstrates nonlinear elimination (metabolism) using phenytoin as the model drug. Specifically, it demonstrates how increasing doses of the drug produce disproportionate increases in the plasma concentration. It also demonstrates how the model parameters, Km and Vmax influence of the plasma concentration -time profile.
Link to Model

Basic Pharmacokinetics and Pharmacodynamics: An Integrated Textbook and Computer Simulations 2nd Edition
By: Sara E. Rosenbaum
Purchase from Amazon