Hydrolysis polymer adsorption affected

Moisture is also an important factor that can affect the stability of candidate drugs and their formulations. Sorption of water molecules onto a candidate drug (or excipient) can often induce hydrolysis (see, e.g., Yoshioka and Cartensen 1990). In this situation, by sorbing onto the drug-excipient mixture, the water molecules may ionize either or both of them and induce a reaction. For example, we have found that a primary amine, when mixed with lactose, was apparently stable even when stored at 90°C for 12 weeks. However, when the experiment was carried out in the presence of moisture, extensive degradation by way of the well-known Mailliard reaction took place. Other properties such as crystal structure, powder flow, compaction, lubricity, dissolution rate and polymer film permeability may also be affected by moisture adsorption (Ahlneck and Zografi 1990). 

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