Application of mathematical modelling in sustained release delivery systems

Introduction: This review, presenting as starting point the concept of the mathematical modelling, is aimed at the physical and mathematical description of the most important mechanisms regulating drug delivery from matrix systems. The precise knowledge of the delivery mechanisms allows to set up powerful mathematical models which, in turn, are essential for the design and optimization of appropriate drug delivery systems. Areas covered: The fundamental mechanisms for drug delivery from matrices are represented by drug diffusion, matrix swelling, matrix erosion, drug dissolution with possible re-crystallisation (as in the case of amorphous and nano-crystalline drugs, for example), initial drug distribution inside the matrix, matrix geometry, matrix size distribution (in the case of spherical matrices of different diameter) and osmotic pressure. Depending on matrix characteristics, the above reported variables may play a different role in drug delivery; thus the mathematical model needs to be built solely on the most relevant mechanisms of the particular matrix considered. Expert opinion: Despite the somewhat diffident behaviour of the industrial world, in the light of the most recent findings, we believe that mathematical modelling may have a tremendous potential impact in the pharmaceutical field. We do believe that mathematical modelling will be more and more important in the future especially in the light of the rapid advent of personalised medicine, a novel therapeutic approach intended to treat each single patient instead of the “average” patient.