Although oral drug delivery is the preferred administration route and has been used for centuries, modern drug discovery and development pipelines challenge conventional formulation approaches and highlight the insufficient mechanistic understanding of processes critical to oral drug absorption. This review presents the opinion of UNGAP scientists on four key themes across the oral absorption landscape: (1) specific patient populations, (2) regional differences in the gastrointestinal tract, (3) advanced formulations and (4) food-drug interactions. The differences of oral absorption in pediatric and geriatric populations, the specific issues in colonic absorption, the formulation approaches for poorly water-soluble (small molecules) and poorly permeable (peptides, RNA etc.) drugs, as well as the vast realm of food effects, are some of the topics discussed in detail. The identified controversies and gaps in the current understanding of gastrointestinal absorption-related processes are used to create a roadmap for the future of oral drug absorption research.

By Zahari Vinarov, Bertil Abrahamsson, Per Artursson, Hannah Batchelor, Philippe Berben, Andreas Bernkop-Schnürchg, James Butler, Jens Ceulemans, Nigel Davies, Didier Dupont, Gøril Eide Flaten, Nikoletta Fotaki, Brendan T.Griffin, Vincent Jannin, Janneke Keeminki, Filippos Kesisoglou, Mirko Koziolek, Martin Kuentz, Alan Mackie, Antonio J. Meléndez-Martínez, Mark McAllister, Anette Müllertz, Caitriona M.O’ Driscoll, Neil Parrott, Jadwiga Paszkowska, Petr Pavek, Christopher J.H.Porter, Christos Reppasa Cordula Stillhart, Kiyohiko Sugano, Elena Toader, Kateřina Valentová, Maria Vertzoni, Saskia N. De Wildt, Clive G. Wilson, Patrick Augustijns