TY - JOUR TI - Current challenges and future perspectives in oral absorption research: An opinion of the UNGAP network AU - Vinarov, Z. AU - Abrahamsson, B. AU - Artursson, P. AU - Batchelor, H. AU - Berben, P. AU - Bernkop-Schnürch, A. AU - Butler, J. AU - Ceulemans, J. AU - Davies, N. AU - Dupont, D. AU - Flaten, G.E. AU - Fotaki, N. AU - Griffin, B.T. AU - Jannin, V. AU - Keemink, J. AU - Kesisoglou, F. AU - Koziolek, M. AU - Kuentz, M. AU - Mackie, A. AU - Meléndez-Martínez, A.J. AU - McAllister, M. AU - Müllertz, A. AU - O'Driscoll, C.M. AU - Parrott, N. AU - Paszkowska, J. AU - Pavek, P. AU - Porter, C.J.H. AU - Reppas, C. AU - Stillhart, C. AU - Sugano, K. AU - Toader, E. AU - Valentová, K. AU - Vertzoni, M. AU - De Wildt, S.N. AU - Wilson, C.G. AU - Augustijns, P. JO - ADVANCED DRUG DELIVERY REVIEWS PY - 2021 VL - 171 TODO - null SP - 289-331 PB - Elsevier B.V. SN - 0169-409X TODO - 10.1016/j.addr.2021.02.001 TODO - Drug interactions; Water absorption, Future perspectives; Gastrointestinal absorptions; Gastrointestinal tract; Oral drug absorption; Oral drug delivery; Patient population; Regional differences; Small molecules, Drug delivery, carotenoid; drug; drug metabolizing enzyme; drug, amorphous solid dispersion; cardiovascular disease; colon absorption; computer analysis; computer model; coronavirus disease 2019; dietary fiber; drug absorption; drug bioavailability; drug dosage form; drug formulation; drug metabolism; drug penetration; drug research; drug solubility; drug transport; food drug interaction; gastrointestinal absorption; gastrointestinal tract; geriatrics; human; in vitro study; in vivo study; inflammatory bowel disease; intestine flora; kidney disease; lymphatic parameters; lymphatic transport; metabolic disorder; oral absorption; pediatrics; Review; stomach juice; water solubility; animal; chemistry; computer simulation; intestine absorption; metabolism; oral drug administration, Administration, Oral; Animals; Computer Simulation; Drug Compounding; Food-Drug Interactions; Gastrointestinal Tract; Humans; Intestinal Absorption; Pharmaceutical Preparations TODO - 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. © 2021 The Authors ER -