The talk starts with the first applications of first-order kinetics in Physics. It introduces the Bateman equation based on a model with three radioactive species, namely, mother, daughter and granddaughter. This equation was adopted by Dost in 1953 to describe the concentration-time curve of drug absorption after oral administration assuming one-compartment model system. The extensive use of first-order kinetics in oral drug absorption phenomena along with the governing role of the absorption rate constant will be described. Emphasis will be given to the unphysical assumption of infinite time of absorption associated with the use of Bateman equation in pharmacokinetics. A minimal model of gastrointestinal drug absorption based on the Finite Absorption Time (F.A.T.) concept will be described. The assumptions of the model are as follows: i) Drugs are absorbed passively under sink conditions. ii) The limiting property is solubility and/or permeability in accord with drug’s BCS classification. iii) Physiological time limits were applied for drug absorption in the small intestines or colon. Differential equations for drug’s permeation rate were written considering the drug’s BCS classification. Simulations were carried out using the model equations. Fittings of these equations were also performed to experimental data.

Panos Macheras, Ph.D.

Panos Macheras is Emeritus Professor (after obligatory retirement September 2014) of the Department of Pharmacy at the National and Kapodistrian University of Athens, Athens, Greece. He is the founder (1991) of the Laboratory of Biopharmaceutics and Pharmacokinetics at the University of Athens. In 2016, he established the PharmaInformatics Unit of the Research and Innovation Center ATHENA; he is currently head of the Unit. He has been Adjunct Professor, Department of Pharmaceutical Sciences, State University of New York (SUNY), Buffalo, USA, since 1/2/2018.

He received his B. Pharm. (1970) and Ph.D. degree in Pharmaceutical Chemistry (1977) from the University of Athens, Greece. He also received a Ph.D. degree (1981) in Biopharmaceutics-Pharmacokinetics from King's College, University of London, U.K. He was Visiting Associate Professor at the College of Pharmacy, University of Michigan (Sabbatical 1988). He has published more than 180 journal articles (7000 citations, h=40 in google) and seven books in the field of Biopharmaceutics-Pharmacokinetics-Pharmacodynamics. His research interests include experimental, theoretical and computational (modeling and simulation) studies on drug dissolution, release, gastrointestinal absorption, protein binding, drug-cyclodextrins interaction, bioequivalence, biopharmaceutic classification of drugs, pharmacokinetics, fractal and fractional kinetics, applications of fractal concepts in biopharmaceutical systems and nonlinear dynamics. He has received many international awards and honors e.g. he was selected by the AAPS to receive the 2014 Dale E. Wurster award in pharmaceutics, (San Diego, CA), he received “Commander of the Order of Honor” award by the Hellenic Republic, 2015, he received two Honorate degrees (Doctor honoris causa), from the Semmelweis University Budapest, Hungary 2015 and from the University of Bucharest, Romania 2007, he selected as the recipient of the 2010 Pharmaceutical Sciences World Congress Research Achievement Award (New Orleans), he received the nation-wide "2011 Xanthopoulos-Pneumatikos Award for Outstanding Academic Teaching" 

He serves on the Editorial Board of the journals Pharmaceutical Research, International Journal of Pharmaceutics and European Journal of Pharmaceutical Sciences.