• Archives of Pharmacal Research
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• v.3 no.1
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• pp.13-16
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• 1980

The model of an isolated organ system has been constructed to simulated the behavior of drug in the circulatory system of an acting organ or site. The model is developed on the following assumptions : The drug in the microcirculatory system cannot permeate the capilary walls. The capilary bed is modeled as a simple ideal plug flow system with and without radial concentration gradient. The mathematical model is developed from basic considerations of drug distribution with hemodynamical and pharmacokinetical meanings. It is considered that a nonmetabolic drug substance is injected into the arterial inflow site of an isolated organ at a constant rate. The concentration of the drug in the outflow site is mathematically expressed as a function of time.

• Progress in Medical Physics
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• v.18 no.3
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• pp.161-166
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• 2007

A model theory of passive-targeted drug delivery in sphere-shaped solid tumors is introduced on the basis of Fick's law of diffusion, with appropriate boundary and initial conditions. For a uniform initial concentration inside the tumor, the concentration is obtained as a function of time and radial position. The concentration is shown to approach the equilibrium distribution as the time elapses, as is expected by the Gedanken Experiment. The time-evolution rate is found to be determined by the diffusion coefficient of the drug in the tissue, the size of the tumor, the volume of the drug-injected region, and the concentration gradient at the boundary.