Drug delivery and in vivo absorption

It is probably not well known that 4000 years B.C. Sumerians were able to prepare many medicaments and illness was considered a sort of divine punishment while healing was the consequent purification, a viewpoint that have heavily affected the western world up to the modern age. The scientific darkness permeating Europe after the end of the Roman Empire favoured the survival of this concept while the golden age of the Arab Science (9th -13th centuries) and Renaissance represented the seeds of a paramount change. However, it is only at the end of the 19th century that, under a rigorous experimental Galilean approach, the real origins of many diseases were discovered. As a matter of fact, the modern age of drug delivery started after the 2nd world war and the first example of mathematical modelling in this field dates back to 1961. The clear affirmation of mathematical modelling in the biopharmaceutical field took place in the last twenty years of the 20th century thanks to valuable researchers such as Peppas and Langer. The third millennium opened with new important challenges such as the simultaneous modelling of drug release, Adsorption, Distribution Metabolism and Elimination (ADME), processes that rule drug fate in vivo. Thus, the aim of this chapter is to describe and to comment the most recent advances in the mathematical modelling of drug release and ADME processes in the light of Paracelsus’ belief of the human body as a chemical plant.