Abstract
In this paper, we consider a multi-layer diffusion model of drug release from a composite
spherical microcapsule into an external surrounding medium. Based on this model, we present two approaches
for estimating the release time, i.e. the time required for the drug-filled capsule to be depleted. Both approaches
make use of temporal moments of the drug concentration at the centre of the capsule, which provide useful
insight into the timescale of the process and can be computed exactly without explicit calculation of the full
transient solution of the multi-layer diffusion model. The first approach, which uses the zeroth and first temporal
moments only, provides a crude approximation of the release time taking the form of a simple algebraic expression
involving the various parameters in the model (e.g. layer diffusivities, mass transfer coefficients, partition
coefficients) while the second approach yields an asymptotic estimate of the release time that depends on
consecutive higher moments. Through several test cases, we show that both approaches provide a computationally-
cheap and useful tool to quantify the release time of composite microcapsule configurations.
Anno
2019
Autori IAC
Tipo pubblicazione
Altri Autori
G. Pontrelli, E. Carr