Moisture with hydrophilic excipient

In this era of automatic titrators, microprocessor-controlled thermal analysis, and definitive spectral techniques, one of the most powerful techniques, that is, optical microscopy, is frequently overlooked. The value of direct sample observation, preferably while it is exposed to different relative humidities, cannot be overstated. In the author s laboratory, a plexiglass chamber was constructed that can be placed on the stage of the microscope, through which air of known humidity can be circulated. This simple technique has been very useful in examining the swelling (or lack) of disintegrants and the influence of very hydrophilic excipients in combination with a moisture sensitive drug. ... 

Finally, the complicated situation faced when a moisture sensitive drug is combined with an hydrophilic excipient is shown in Fig. 24. In this study, aspirin... 

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