The water sorption isotherms
were measured for several anhydrous crystalline solids, an
isolated site hydrate, a channel hydrate, and an amorphous
polymer. Specifically, the compounds selected represent “nonhygroscopic”
anhydrous drugs (genistein, indomethacin, and
griseofulvin), the nonhygroscopic excipient lactose monohydrate,
the hygroscopic channel hydrate erythromycin
A dihydrate, and the hygroscopic amorphous excipient
polyvinylpyrrolidone (PVP K29-32)