A review of GI conditions critical to oral drug absorption in malnourished children.

Accurate prediction of oral absorption of drugs relies on biorelevant methodology. Current methods are based on Western healthy adult populations. Malnourished children have many differences in their gastrointestinal anatomy and physiology compared to a healthy Western adult. These differences may affect the oral absorption of medicines and it is important to gather knowledge on these GI differences in order to develop biorelevant predictive methods for this vulnerable population. A literature search was conducted within PubMed and Scopus to identify papers that describe how gastrointestinal physiology and anatomy is altered in malnourished children. Relevant data was extracted and a narrative review generated to describe how GI differences may affect oral drug absorption. Several differences in GI anatomy and physiology were reported in the literature including: reduced saliva secretion; increased gastric pH; slower gastric emptying; increased levels of bacteria in the small intestine; reduced surface area of intestinal villi and increased intestinal permeability. Much of the data was more than 30 years old and referred to a heterogeneous malnourished population. Sufficient data has been identified that will inform basic novel biorelevant methods to predict oral drug absorption in malnourished children. Further work is required to generate additional data to improve these models and also to verify the models with appropriate pharmacokinetic data.