The delivery of medication across skin tissue with a transdermal drug delivery(TDD) system is dependent on the transport mechanism called diffusion. Diffusion is influenced by the following important local variables: 1) Scale of the species; 2) Convection conditions; 3) Environmental conditions; 4) Time scale; and 5) other Material Properties (mechanical, electrical, chemical, biological). The goal of this research is to model and study the mechanisms of transport of medication from a foreign source to a target site within the human body. This project focuses on bio-mechanics aspects of diffusion.
An approximation of the second order non-homogeneous equation for diffusion in two-dimension is made numerically through the use of a finite-difference method (Crank-Nicolson). A FORTRAN program is developed to generate concentration data for a grid area over time. Visualization of the output resulting from this program is used to help understand the intricacies of the diffusion model. The diffusion model is representative of the transport of medication from the TDD system to the first metabolically active site within the tissue. Metabolic processes add nonlinear and unquantifiable phenomena to the diffusion model of drug transport. In conclusion the medication transport model will be improved when the effects of metabolic processes are included in the diffusion model.
Page Section 1. Introduction -Introduction 1 -Current drug delivery systems 2 -Problem definition 3 Section 2. The Analytical Transdermal Drug Deliver Model -Formation of a diffusion model 5 -Transport parameters 7 -Main variables 9 Scale and geometry Heat dissipation Competing mechanisms Section 3. The Numerical Diffusion Model -Program information 14 -Defining input variables 15 -Visualizing the output 16
Section 4. Conclusion -Conclusions 20 -Recommendations and future work 21 Acknowledgments 23 References 24 Appendices I Numerical Implementation of Finite Difference Theory II Finite Difference Model Theory 25 III Download FORTRAN program and data files 34
Sanjiv D. Parikh
College of Engineering