Multi-scale Drug Release Modeling for Targeted Oral Drug Delivery (TODD)
B.N. Haddish, C. Nyquist, K. Haghighi, H-A Wu, C. Corvalan, J. Rickus and A. Keshavarzian
Purdue University, US
drug delivery, targeted, drug release, mathematical modeling, multi-scale, numerical methods, stochastic modeling
Conventional oral dosage forms deliver their active ingredient at rates that are high initially and decline afterward, showing a first order kinetics with the release determining step considered as the dissolution rate of the active ingredient. However, dosage forms are now being replaced by smart delivery systems (e.g. TODD) that exhibit complex non-linear drug release kinetics. This study deals with the development of a multi-scale mathematical model of the drug release of different commercially available delayed release capsules that deliver 5-ASA (5-Aminosalicylic Acid) to the colon, based on underlying physical and biochemical principles governing the involved processes (e.g., diffusion, dissolution). It was attempted to derive macro-scale transport properties of the capsule components and their interaction with the drug molecule from their molecular descriptors. Coarse grain molecular simulation work is in progress to estimate the transport properties that serve as coupling coefficients between the micro and macro-scales. The existing inter/intra subject variability of the gastrointestinal tract (GIT) environmental factors (e.g. pH and residence time) is also taken into account. The model was validated using in-vitro dissolution experimental data performed by mimicking different pH conditions. Some initial simulation results look promising and the experimental work to obtain the data is underway.
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Nanotech 2005 Conference Program Abstract