Abstract
Various swelling drug delivery devices are promising materials for control drug delivery because of their ability to swell and release entrapped therapeutics, in response to physiological stimuli. Previously, many mathematical models have been developed to predict the mechanism of drug release from a swelling device. However, some of these models do not consider the changes in diffusion behaviour as the device swells. Therefore, we used a two-phase approach to simplify the mathematical model considering the effect of swelling on the diffusion coefficient. We began by defining a moving boundary problem to consider the swelling process. Landau transformation was used for mitigating the moving boundary problem. The transformed problem was analytically solved using the separation of variables method. Further, the analytical solution was extended to include the drug release in two phases where each phase has distinct diffusion coefficient and continuity condition was applied. The newly developed model was validated by the experimental data of bacterial cellulose hydrogels using the LSQCURVEFIT function in MATLAB. The numerical test showed that the new model exhibited notable improvement in curve fitting, and it was observed that the initial effective diffusion coefficient of the swelling device was lower than the later effective diffusion coefficient.
Highlights
The safe and effective delivery of therapeutics at the target site of action is a challenging task for drug delivery scientists
In this study, we developed a mathematical model for estimating drug release from a swelling hydrogel-based drug delivery device considering the dynamical constant diffusion coefficient by adopting the idea of two-phase drug release
We successfully developed a new two-phase drug release model considering device swelling
Summary
The safe and effective delivery of therapeutics at the target site of action is a challenging task for drug delivery scientists. Numerous mathematical models have been presented for hydrogel-based drug delivery devices, which have been reviewed comprehensively in other studies [13,14,16] The development of these drug release models began with Fick’s law of diffusion, and other phenomena, such as swelling, polymer degradation, the microstructure of hydrogel, glassy/rubbery shifts, the geometry of the drug delivery device, and stimuli response, were considered in these mathematical models [13]. Peppas et al introduced an empirical equation by assuming a time-dependent power law function, which is widely used in the study of drug release owing to its simplicity [13] This model helps in distinguishing the different release mechanisms of a device that can be swelling-controlled, diffusion-controlled, or anomalous transport. In this study, we developed a mathematical model for estimating drug release from a swelling hydrogel-based drug delivery device considering the dynamical constant diffusion coefficient by adopting the idea of two-phase drug release.
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