Many commercial
drug products contain a storage statement on the label
around moisture protection, and may contain a desiccant or
special packaging, underscoring water’s relevance to detrimental
changes that it can produce on storage.
Most drugs are crystalline solids that generally sorb only
a small amount of water from the atmosphere, for example,
0.1%–0.2% water at a relative humidity (RH) as high as 90%.
The reason for the low sorption level is that water molecules