Inverse gas chromatography
A novel finite dilution IGC technique for the physicochemical characterization and optimization of dry powder inhalation formulations.
In the October 2007 issue of Inhalation, Andrew Otte and M. Teresa Carvajal presented a comprehensive overview of solid surface energy principles and applied measurement techniques for DPI formulations, including infinite dilution inverse gas chromatography (IGC).
This follow-up article focuses specifically on the use of IGC for the determination of surface energy as a function of processing conditions for both API and excipient carrier molecules used in inhalable formulations and introduces a novel finite dilution approach that offers a unique new method of profiling surface heterogeneity, which plays a major role in drug-carrier interactions. This extremely sensitive approach provides data of unparalleled specificity that can benefit every stage of the DPI formulation process.