Pharmacokinetic modeling of gastric emptying and small intestinal transit time in dogs using paracetamol and sulfasalazine as markers

In this thesis, two pharmacokinetic models are evaluated with respect to their capacity to quantify gastric emptying and small intestinal transit in dogs. The experiments are based on the double marker technique, which uses two drug substances (paracetamol and sulfasalazine) that are absorbed in the duodenum and the colon, respectively. A standard model is compared to a more sophisticated transit rate model. It is shown that both models provide reasonable predictions for the plasma levels of paracetamol, but for the sulfasalazine data, the transit rate model produce considerably better fit than the standard model. Based on this study, the transit rate model seems to be the best choice for the analysis of double marker experiments.