A multiscale computational study of the effects of fluid flow and drug metabolism on drug delivery

In this study, a heterogeneous multiscale method based mass transport model is developed for delivering drug into biological tissues. In the model, fluid flow and drug metabolism are modelled at the continuum scale, whereas the diffusion phenomenon is incorporated through macro-micro coupling. Darcy's law is used for fluid flow calculation, and the drug metabolism is determined using the Michaelis-Menten equation. Using the model, penetration and distribution of a drug in a tissue are investigated. Mainly, the effects of fluid flow and drug metabolism together with the particle size effects on drug delivery are explored. It is observed that the particles of sizes 10 and 100 nm can penetrate the tissue with advection; however, without advection, such particles accumulate around the capillary, the source of the drug to the interstitium. In fluid flow regions, drug metabolism may not affect penetration and distribution of drug; the results are similar to those without drug metabolism. However, metabolism may significantly reduce drug penetration in the absence of fluid flow. It is observed from the sensitivity analysis that the model is most sensitive to the parameters that model the transport processes of extracellular space while least sensitive to those that incorporate the intracellular processes.