As I recently retired from Chiba University, I would like to describe how I began my research career, some of my accomplishments in the research field of modeling and simulation, and future prospects in this area. Here, I discuss the research topics of drug interactions, the oral absorption of drugs, analyses of between-group and individual differences in pharmacokinetics based on the theories of physiologically-based pharmacokinetics and population pharmacokinetics, and my roles in implementation of the drug interaction guideline. Furthermore, I also discuss modeling topics unrelated to pharmacokinetics, i.e., the analyses of the long-term progression of chronic diseases, such as Alzheimer's disease, Parkinson's disease, and chronic obstructive pulmonary disease using individual patient information
the spread of the coronavirus disease 2019 (COVID-19) pandemic
and prognostic factors of chronic heart failure with the view towards personalized medicine. After completing my Master's course at Hokkaido University, I joined a pharmaceutical company and worked as a pharmacokinetics researcher for 21 years, while obtaining my doctoral degree. I spent the next 9 years as a hospital pharmacist focusing on scientific research at the University of Tokyo Hospital, and the last 10 years as a Professor of Clinical Pharmacology and Pharmacometrics at Chiba University. My career is, therefore, characterized by involvement in pharmaceutical sciences from many different perspectives. This description focuses rather on the background of the studies than scientific details.