Moisture sorption and volume expansion of amorphous lactose tablets.

Abstract

Measurements of the moisture sorption and the volume expansion of amorphous lactose tablets, as well as measurements of the formation of crystalline lactose, were carried out under controlled relative humidities. At high relative humidity, it was suggested that the supersaturated solution of lactose was formed on some parts of the surface of amorphous lactose particles and the crystallization occured in an autocatalytic manner, which led to a rapid expansion of tablets. On the other hand, at low relative humidity, it appeared that the hygroscopic swelling owing to the physical adsorption of moisture on the inner surface of tablets occured without crystallization.