Characterisation of fasted state gastric and intestinal fluids collected from children

Fundamental knowledge about the composition of intestinal fluids in paediatric populations is currently unavailable. This study aimed to characterise gastric and intestinal fluid from paediatric populations. Gastric and intestinal fluid samples were obtained during routine clinical endoscopy from paediatric patients at a large teaching hospital. These fluids were characterised to measure the pH; buffer capacity; osmolality; bile acid concentration and composition. A total of 55 children were recruited to the study aged from 11 months to 15 years of age where 53 gastric fluid samples and 40 intestinal fluid samples were obtained. pH values recorded ranged from pH 0.57 to 11.05 (median: 2.50) in gastric fluids and from 0.89 to 8.97 (median: 3.27) in intestinal fluids. The buffer capacity did not change significantly between gastric and intestinal fluids with median values of 12 mM/L/ΔpH for both fluids. Gastric fluid osmolality values ranged from 1 to 615 mOsm/kg, while intestinal fluid values ranged from 35 to 631 mOsm/kg. Gastric fluid bile acid concentrations ranged from 0.002 to 2.3 mM with a median value of 0.017 mM whilst intestinal fluid bile acid concentrations ranged from 0.0008 to 3.3 mM with a median value of 0.178 mM. Glycocholate; taurocholic acid; glycochenodeoxycholate and taurochenodeoxycholate were the most commonly identified bile acids within paediatric intestinal fluids. All compositional components were associated with large inter-individual variability. Further work is required to develop simulated paediatric media and to explore the impact of these media on drug solubility and dissolution.

Magnetic Resonance Imaging Quantification of Gastrointestinal Liquid Volumes and Distribution in the Gastrointestinal Tract of Children

The volume and localization of fluid in the paediatric gastrointestinal tract is crucial to the design of in vitro and in silico models that predict the absorption of oral drugs administered to children. Previous studies have used magnetic resonance imaging (MRI) to quantify fluid volumes and localization in the intestines of adults; this study is the first to undertake similar analysis of pediatric participants. This study quantified the amount and distribution of fluid in fasted and fluid-fed children using MRI data captured during the routine clinical assessment. Data from 32 fasted children (aged 0-16 years) and 23 fluid-fed children (aged 8-16 years) were evaluated. The gastric volume ranged from 0 to 9 mL in the fasted and 19-423 mL in the fluid-fed state. The small intestinal volume was recorded to be 0-51 mL in the fasted and 6-91 mL in the fluid-fed state with an average number of 7.7 and 22.4 fluid pockets, respectively. The data showed significant differences in gastric volumes and the number of fluid pockets in the small intestine for age-matched fasted and fluid-fed children (p < 0.05). Both the number and the volume of pockets reported in children are much lower than those previously reported in adults. This study is the first to report intestinal volumes and localization in children and provides new information to achieve the design of biorelevant in vitro models and real values to update in silico models. The data available from both fluid-fed and fasted children show the extremes of fluid volumes that are present in the gastro-intestinal tract which is useful to understand the variability associated with drug absorption in children.