Agglomeration Effects on the Drying and Dehydration Stability of Pharmaceutical Acicular Hydrate: Carbamazepine Dihydrate

The effects of agglomeration oil the dehydration kinetics and stability of carbamazepine dihydrate were investigated and are reported here. The prepared dihydrate agglomerates were sieved into six particle size distributions, ranging from 75 to similar to 1800 mu m, prior to gravimetric dehydration Studies. It was concluded that when these agglomerates exceed a critical agglomerates size, they then retain an excess amount of physically adsorbed (unbound) water relative to the smaller agglomerate sizes. Specifically, agglomerates with particle diameter > 1400 mu m held up to 57.2 wt% of unbound water, residing within the funicular regime of moisture saturation. These larger agglomerates exhibit I distinct and densely packed particle structure, leading to a relatively more stable dihydrate, having a lower critical humidity of 20% RH (0.0039 kg(water)/kg(air)) at 25 degrees C, than those agglomerates without inclusion Of unbound water. This work demonstrates that the moisture stability performance of agglomerated solids is dependent both on the intrinsic water sorption properties of the component materials its well as the local microstructure that evolves within the agglomerated solids. Furthermore, this work also demonstrates that the moisture stability of a solid state form call be strongly influenced by local particle microstructure, Which thus provides another strategy for improving moisture stability of formulated products.