Abstract
Dissolution of drug from its solid form to a dissolved form is an important consideration in the design and
optimization of drug delivery devices, particularly owing to the abundance of emerging compounds that are
extremely poorly soluble. When the solid dosage form is encapsulated, for example by the porous walls of an
implant, the impact of the encapsulant drug transport properties is a further confounding issue. In such a case,
dissolution and diffusion work in tandem to control the release of drug. However, the interplay between these
two competing processes in the context of drug delivery is not as well understood as it is for other mass transfer
problems, particularly for practical controlled-release considerations such as an encapsulant layer around the
drug delivery device. To address this gap, this work presents a mathematical model that describes controlled
release from a drug-loaded device surrounded by a passive porous layer. A solution for the drug concentration
distribution is derived using the method of eigenfunction expansion. The model is able to track the dissolution
front propagation, and predict the drug release curve during the dissolution process. The utility of the model is
demonstrated through comparison against experimental data representing drug release from a cylindrical drugloaded
orthopedic fixation pin, where the model is shown to capture the data very well. Analysis presented here
reveals how the various geometrical and physicochemical parameters influence drug dissolution and, ultimately,
the drug release profile. It is found that the non-dimensional initial concentration plays a key role in determining
whether the problem is diffusion-limited or dissolution-limited, whereas the nature of the problem is largely
independent of other parameters including diffusion coefficient and encapsulant thickness. We expect the model
will prove to be a useful tool for those designing encapsulated drug delivery devices, in terms of optimizing the
design of the device to achieve a desired drug release profile.
Anno
2023
Autori IAC
Tipo pubblicazione
Altri Autori
Ankur Jain, David King, Giuseppe Pontrelli, Sean McGinty
Editore
Elsevier
Rivista
Journal of controlled release