The improved dissolution performance of a post processing treated spray-dried crystalline solid dispersion of poorly soluble drugs

Context: Solution-mediated transformation has been cited as one of the main problems that deteriorate dissolution performances of solid dispersion (SD). This is mainly attributed by the recrystallization tendency of poorly soluble drug. Eventually, it will lead to extensive agglomeration which is a key process in reducing the dissolution performance of SD and offsets the true benefit of SD system. Here, a post-processing treatment is suggested in order to reduce the recrystallization tendency and hence bring forth the dissolution advantage of SD system. Objectives: The current study investigates the effect of a post processing treatment on dissolution performance of SD in comparison to their performances upon production. Methods: Two poorly soluble drugs were spray dried into SD using polyvinyl alcohol (PVA) as hydrophilic carrier. The obtained samples were post processing treated by exposure to high humidity, i.e. 75% RH at room temperature. The physical properties and release rate of the SD system were characterized upon production and after the post-processing treatment. Results and discussion: XRPD, Infrared and DSC results showed partial crystallinity of the fresh SD systems. Crystallinity of these products was further increased after the post-processing treatment at 75% RH. This may be attributed to the high moisture absorption of the SD system that promotes recrystallization process of the drug. However, dissolution efficiencies of the post-treated systems were higher and more consistent than the fresh SD. The unexpected dissolution trend was further supported by the results intrinsic dissolution and solubility studies. Conclusions: An increase of crystallinity in a post humidity treated SD did not exert detrimental effect to their dissolution profiles. A more stabilized system with a preferable enhanced dissolution rate was obtained by exposing the SD to a post processing humidity treatment.