Results from a New Mathematical Model of Gastrointestinal Transit that Incorporates Age and Gender-Dependent Physiological Parameters

Recently published data on effects of age- and gender-dependent GI physiology and motility have been used to develop a new mathematical model describing the transit and absorption of substances through the GI tract. This mathematical description of GI tract kinetics utilises more physiologically accurate transit processes than the ICRP Report 30 GI model. The model uses a combination of zero- and first-order kinetics to describe motility. Some of the physiological parameters that the new model uses are gender, age phase of the menstrual cycle, meal composition and gastric phase (solid versus liquid). A computer algorithm based on this model has been derived and results for young males are compared to those of the ICRP 30 model. Comparison of gastrointestinal residence times for 99Tcm and 111In labelled compounds, as a function of gender and age are also presented.