Application of tiny-TIM as a mechanistic tool to investigate the in vitro performance of different itraconazole formulations under physiologically relevant conditions

The increasing number of poorly water-soluble compounds in drug development is one of the major challenges in oral drug delivery nowadays. For rational formulation development, biopharmaceutical tools are needed that closely simulate the conditions present within the human gastrointestinal (GI) tract in order to early predict the potential effect of important factors like meal intake or acid-reducing agents on oral bioavailability. The tiny-TIM system equipped with the advanced gastric compartment is one of the most realistic in vitro models for the simulation of the physiological processes occurring in human stomach and small intestine. In the present study, this model was applied to study the in vitro performance of an ASD-based formulation of itraconazole under different clinically relevant conditions. Apart from the assessment of the bioaccessible fraction (i.e., the fraction available for drug absorption), the implementation of two additional sampling ports enabled the measurement of intraluminal concentration profiles. Along with solubility experiments in biorelevant media, deeper mechanistic insights into drug product performance in different prandial states as well as in case of gastric pH modification could be generated. The comparison of the in vitro data with published in vivo data revealed that the model successfully predicted the effect of food intake as well as of modified gastric pH conditions on the bioavailability of itraconazole from this formulation. In contrast, the negative food effect observed for an oral solution formulation could not be predicted. For this cyclodextrin-based formulation, the formulation effect on permeation needs to be considered. Nonetheless, the data presented in this study showed that tiny-TIM is an interesting tool to mechanistically study the impact of different physiological conditions on drug release from oral drug products.