Implementation of transmission NIR as a PAT tool for monitoring drug transformation during HME processing.

The aim of the work reported herein was to implement process analytical technology (PAT) tools during hot melt extrusion (HME) in order to obtain a better understanding of the relationship between HME processing parameters and the extruded formulations. For the first time two in-line NIR probes (transmission and reflectance) have been coupled with HME to monitor the extrusion of the water insoluble drug indomethacin (IND) in the presence of Soluplus (SOL) or Kollidon VA64 hydrophilic polymers. In-line extrusion monitoring of sheets, produced via a specially designed die, was conducted at various drug/polymer ratios and processing parameters. Characterisation of the extruded transparent sheets was also undertaken by using DSC, XRPD and Raman mapping. Analysis of the experimental findings revealed the production of molecular solutions where IND is homogeneously blended (ascertained by Raman mapping) in the polymer matrices, as it acts as a plasticizer for both hydrophilic polymers. PCA analysis of the recorded NIR signals showed that the screw speed used in HME affects the recorded spectra but not the homogeneity of the embedded drug in the polymer sheets. The IND/VA64 and IND/SOL extruded sheets displayed rapid dissolution rates with 80% and 30% of the IND being released, respectively within the first 20min.

Prediction of polymorphic transformations of paracetamol in solid dispersions.

A novel approach employing variable-temperature X-ray powder diffraction (VTXRPD) was used to exploit its suitability as an off-line predictive tool to study the polymorphic transformations of paracetamol (PMOL) in melt-extruded hydrophilic polymer matrices. Physical mixtures (PMs) and extruded formulations of PMOL with either polyvinyl caprolactam graft copolymer (Soluplus®) or vinylpyrrolidone-vinyl acetate copolymer (Kollidon®) in the solid state were characterized by using differential scanning calorimetry, hot-stage microscopy, and scanning electron microscopy. The experimental findings from VTXRPD showed that the stable Form I (monoclinic) of PMOL transformed to the metastable polymorph Form II (orthorhombic) at temperatures varying from 112°C to 120°C, in both the PMs and extrudates suggesting an effect of both temperature and identity of the polymers. The findings obtained from VTXRD analysis for both the PMs and the extruded formulations were confirmed by in-line near-infrared (NIR) monitoring during the extrusion processing. In the NIR study, PMOL underwent the same pattern of polymorphic transformations as those detected using VTXPRD. The results of this study suggest that VTXRPD can be used to predict the polymorphic transformation of drugs in polymer matrices during extrusion processing and provides a better understanding of extrusion processing parameters.

Development of sustained-release formulations processed by hot-melt extrusion by using a quality-by-design approach.

In this study, a quality-by-design (QbD) approach was used to optimize the development of paracetamol (PMOL) sustained-release formulations manufactured by hot-melt extrusion (HME). For the purpose of the study, in-line near-infrared (NIR) spectroscopy as a process analytical technology (PAT) was explored while a design of experiment (DoE) was implemented to assess the effect of the process critical parameters and to identify the critical quality attributes (CQA) of the extrusion processing. Blends of paracetamol, ethyl cellulose (EC) and Compritol® 888 ATO (C888) were processed using a twin screw extruder to investigate the effect of screw speed, feed rate and drug loading on the dissolution rates and particle size distribution. The principal component analysis (PCA) of the NIR collected signal revealed the optimum extrusion processing parameters. Furthermore, the integration of the DoE experiments demonstrated that drug loading has a significant effect on the only quality attribute, which was the PMOL dissolution rate. This QbD approach was employed as a paradigm for the development of pharmaceutical formulations via HME processing.