Surface characterization of pharmaceutical solids

Surface properties alter solid solid and solid liquid interfacial interactions that profoundly impact manufacturability, processability, dissolution kinetics and stability of pharmaceutical solids. Surface properties may alter due to differential chemistry at the surface of the solid. Surface heterogeneity is driven by exposure of different crystalline facets and molecular arrangement, crystal habit, disordered lattice structure, surface functionalization and surface energy. A pre requisite in surface characterization is to access topmost layer of a solid with extreme sensitivity and resolution. The surface characterization can be performed by a variety of qualitative and quantitative analytical tools operating on principles of vapor surface interaction, liquid surface interaction, micro scopic imaging using electron beam or mechanical probe, spectroscopy, mass spectrometry and calorimetry. The current review introduces each technique from fundamental principle, instrumentation, meth odologies and sample preparation to specific applications in relation to surface characterization. A compilation of surface properties has also been presented to enable selection of an appropriate analytical tool for their characterization. (c) 2021 Elsevier B.V. All rights reserved.

Automated summary

Surface properties play a crucial role in impacting manufacturability, processability, dissolution kinetics, and stability of pharmaceutical solids by altering solid-solid and solid-liquid interfacial interactions. Surface characterization requires sensitive analytical tools that can access the topmost layer of a solid and can be performed using techniques like spectroscopy, microscopy, mass spectrometry, and calorimetry. Understanding and selecting appropriate analytical tools are essential for characterizing surface properties effectively.