Moisture solid drug stability

Despite recent advances in understanding the influence of moisture on the physical state of the solid, it is perhaps the effect of sorbed moisture on the chemical stability of moisture-sensitive drugs that is most important, particularly because many new bioactive agents are expensive moisture-sensitive proteins. 

The hydration state of risedronate sodium was monitored continuously in a fluidized bed dryer and correlated to data on the physical stability of tablets made from the monitored material [275]. The final granulation moisture was found to affect the solid-state form, which in turn dictated the drug s physical stability over time. The process of freeze-drying mannitol was monitored continuously with in-line Raman and at-line NIR spectroscopies [276]. The thin polymer solvent coatings, such as poly(vinyl acetate) with toluene, methanol, benzene, and combinations of the solvents, were monitored as they dried to generate concentra-tion/time profiles [277]. 

Ahlneck C, Zografi G. The molecular basis of moisture effects on the physical and chemical stability of drugs in the solid state. Int J Pharm 1990 62 87-95. 

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