The instantaneous concentration of alcohol at a time t is represented by C(t). Change in concentration over time is represented by dC(t)/dt. Vmax represents the maximum metabolism rate. Km is known as the Michaelis-Menten constant and represents the concentration of the drug where metabolism is ½ of the maximal rate. Figure 5 depicts the enzymatic activity of several primary ADH isoforms as a function of alcohol concentration. It is important to note that the enzymatic activity and concentrations are measured in vitro, and therefore, estimates of Km and Vmax can vary as a function of the experimental conditions. While these studies provide valuable simulations for comparing the kinetics of different isozymes under the same conditions, they represent a simplified model of the complex physiological processes involved in alcohol metabolism in vivo.
