Drug delivery and in vivo absorption

It is probably not well known that 4000 years BC. 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 has heavily affected the Western world up to the modern age. The scientific darkness permeating Europe after the end of the Roman Empire favored 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 World War II and the first example of mathematical modeling in this field dates back to 1961. The clear affirmation of mathematical modeling in the biopharmaceutical field took place in the last 20 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 modeling of drug release, adsorption, distribution metabolism and elimination (ADME), processes that rule drug fate in vivo. Thus, this chapter aims to describe and comment on the most recent advances in the mathematical modeling of drug release and ADME processes in the light of Paracelsus’ belief of the human body as a chemical plant.