Examining practical feasibility of amorphous curcumin-chitosan nanoparticle complex as solubility enhancement strategy of curcumin: Scaled-up production, dry powder transformation, and long-term physical stability

Amorphous curcumin-chitosan nanoparticle complex (or nanoplex in short) was recently developed as a new solubility enhancement strategy of curcumin (CUR) - a natural herb well known for its vast therapeutic activities. For its subsequent clinical application and commercialization, the present work aimed to address the three remaining research questions pertaining to the CUR nanoplex, i.e. (1) was the nanoplex preparation scalable? (2) could the nanoplex maintain its solubility enhancement capability in the powder form? (3) could the nanoplex resist crystallization, which would jeopardize its solubility enhancement capability, during long-term storage? First, the results showed that gram-scale production of the CUR nanoplex was readily achieved at high CUR utilization rate without significant adverse effects on the physical characteristics. Stable CUR nanoplex with size, zeta potential, and CUR payload of ≈100-300 nm, 18 mV, and 80%, respectively, was produced. The scaled-up production, nevertheless, resulted in lower yield due to lower nanoplex recovery in the purification step. Second, the CUR nanoplex powders, when formulated correctly with drying adjuvants, maintained the solubility enhancement capability of the suspension form, despite their slower dissolution velocity. High apparent solubility at approximately twice of CUR's thermodynamic solubility was demonstrated for 8 h. Third, the CUR nanoplex powders maintained its amorphous state after twelve-month storage when stored as physical mixture with crystallization-inhibiting agents. In short, the present results successfully established the CUR nanoplex as a practical and effective solubility enhancement strategy of CUR.

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