Fig. 6. The relation between the probability of loss of consciousness (LOC) and the effect site concentration of propofol for lipid emulsion ( A ) and microemulsion formulation ( B ). The estimates of Ce50(the effect site concentration of propofol associated with 50% probability of LOC) with SE and interindividual variability presented as % coefficient of variation are 1.73 μg/ml (0.07, 22.0%) for lipid emulsion and 1.67 μg/ml (0.07, 20.9%) for microemulsion. The estimates of γ (the steepness of the concentration- vs. -response relation) with SE and interindividual variability presented as % coefficient of variation are 11.8 (1.13, 50.4%) for lipid emulsion and 12.7 (1.43, 54.4%) for microemulsion. The mean Ce95(the effect site concentration of propofol associated with 95% probability of LOC) with SD is 2.22 ± 0.44 μg/ml for lipid emulsion and 2.11 ± 0.44 μg/ml for microemulsion. Interindividual random variability was modeled using a log-normal model. * Effect site concentrations of propofol at LOC and ROC.