Impact of gastrointestinal tract variability on oral drug absorption and pharmacokinetics: An UNGAP review

Zahari Vinarov, Mohammad Abdallah, José A.G. Agundez, Karel Allegaert, Abdul W. Basit, Marlies Braeckmans, Jens Ceulemans, Maura Corsetti, Brendan T. Griffin, Michael Grimm, Daniel Keszthelyi, Mirko Koziolek, Christine M. Madla, Christophe Matthys, Laura E. McCoubrey, Amitava Mitra, Christos Reppas, Jef Stappaerts, Nele Steenackers, Natalie L. TrevaskisTim Vanuytsel, Maria Vertzoni, Werner Weitschies, Clive Wilson, Patrick Augustijns*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

149 Citations (Scopus)


The absorption of oral drugs is frequently plagued by significant variability with potentially serious therapeutic consequences. The source of variability can be traced back to interindividual variability in physiology, differences in special populations (age- and disease-dependent), drug and formulation properties, or food-drug interactions. Clinical evidence for the impact of some of these factors on drug pharmacokinetic variability is mounting: e.g. gastric pH and emptying time, small intestinal fluid properties, differences in pediatrics and the elderly, and surgical changes in gastrointestinal anatomy. However, the link of colonic factors variability (transit time, fluid composition, microbiome), sex differences (male vs. female) and gut-related diseases (chronic constipation, anorexia and cachexia) to drug absorption variability has not been firmly established yet. At the same time, a way to decrease oral drug pharmacokinetic variability is provided by the pharmaceutical industry: clinical evidence suggests that formulation approaches employed during drug development can decrease the variability in oral exposure. This review outlines the main drivers of oral drug exposure variability and potential approaches to overcome them, while highlighting existing knowledge gaps and guiding future studies in this area.

Original languageEnglish
Article number105812
JournalEuropean Journal of Pharmaceutical Sciences
Publication statusPublished - 1 Jul 2021

Bibliographical note

Funding Information:
This article is based upon work from COST Action UNGAP (CA16205), supported by COST (European Cooperation in Science and Technology), funded by the Horizon 2020 Framework Programme of the European Union.

Publisher Copyright:
© 2021 The Authors


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