Investigating a Novel Hot Melt Extrusion-Based Drying Technique to Solidify an Amorphous Nanosuspension Using Design of Experiment Methodology

The hot melt extrusion (HME) technology was explored and optimized to solidify an amorphous nanosuspension using Quality by Design (QbD) methodology. A design of experiments (DoE) approach was used to perform a set of 15 experiments, varying independent variables (feed rate, input temperature, and screw speed) within a design space. Redispersibility index (RDI), moisture content, and process yield constituted the critical quality attributes (CQAs) of the experimental design. Regression analysis and ANOVA were employed to identify and estimate significant main effects and two-way interactions, and model the process of HME drying for predictive purposes. The optimized HME-dried end product was characterized for physicochemical properties using differential scanning calorimetry (DSC), X-ray powder diffractions (XRPD), polarized light microscopy (PLM), Fourier transform infrared spectroscopy (FTIR), and in vitro dissolution studies. The statistical analysis reveals feed rate and input temperature as significant independent variables, critically influencing RDI and moisture content of solidified end product. The model developed for process yield was insignificant at a p- value of 0.05. The API retained its amorphous nature after the extrusion process which was confirmed using DSC and XRPD techniques. PLM was unsuitable to differentiate and determine crystallinity of drug moiety in the presence of a semi-crystalline bulking agent, microcrystalline cellulose (MCC). In vitro dissolution study depicted solubility and dissolution enhancement for HME-dried amorphous nanosuspension in both the dissolution media which can be attributed to amorphous nature of nanosized drug particles. A well-designed study implemented by DoE aided in developing a robust and novel HME technique to dry aqueous nanosuspension.