According to Dedrick et al, the free drug concentration in the peritoneal cavity is described as its exponential decrease since the drug diffuses down the concentration gradient into the bloodstream. The characteristic diffusion length depends on the distance from the serosal surface (x). At minimal distance (x0), the concentration difference has decreased to 37% of its maximum value. Considering this fact, I used peritoneum-blood diffusion rate for propofol as b = 0.37. The drug concentration in the blood was successfully predicted using a single-compartment model after i.p. injection (Dose = 3.0 mg/ml). Its concentration in the brain was calculated from the experimental logBB value.