| Popis: |
This chapter examines the application of mathematical modeling to transdermal drug delivery. Several robust mathematical models for describing and predicting percutaneous drug delivery have been developed with the aim of reducing animal experiments. Mathematical modeling can also accelerate transdermal product design and provide more reliable safety assessment. In addition, mathematical equations can assist researchers in elucidating transdermal transport mechanisms. Several methods, including analytical and numerical statistical techniques such as finite element modeling, finite difference modeling, finite volume modeling as well as quantitative structure–permeation relationship modeling, are routinely used to characterize transdermal permeation. Diffusion models typically use Fick’s second law of diffusion to predict drug concentrations locally and temporally. Drug diffusion through a transdermal device and the skin can be regarded as Fickian transport through a simple homogeneous membrane or a heterogeneous multilayer membrane. Macroscopic models view the skin as a homogeneous region while more complicated microscopic models focus on the stratum corneum and regard it as corneocytes embedded in anisotropic lipid bilayers or a brick-and-mortar structure with impermeable or permeable corneocyte “bricks” immersed in an isotropic, homogeneous lipid phase “mortar.” Artificial neural network can also be used in transdermal drug delivery research to deal with certain mathematical modeling challenges especially those that cannot be solved with analytical methods. |
