Simulation of fasting gastric conditions and its importance for the in vivo dissolution of lipophilic compounds

In this study, the importance of accurate simulation of fasting gastric environment for the assessment of the absorption process of two model lipophilic compounds, GR253035X (weak base) and atovaquone (non-ionizable), was assessed. Dissolution profiles were constructed in previously proposed simulated gastric fluids and in a new medium that comprises only of components that have been recovered from the fasting stomach. Dissolution data obtained in a more physiologically relevant medium led to better correlation between the simulated and actual intralumenal dissolution vs. time profiles for GR253035X. In contrast, accurate simulation of gastric environment did not affect the simulated plasma profile of atovaquone. Accurate simulation of the fasting gastric contents may be crucial for the assessment of the absorption profile of lipophilic weak bases. (c) 2005 Elsevier B.V. All rights reserved.