Co-processed excipients (CPEs) can be classified as novel excipients. They are combinations of two or more excipients at the sub-particle level with the aim to improve functionality as well as mask the undesirable properties of individual excipients. Excipients combinations through co-processing do not produce any chemical modification in the incorporated excipients. Individual properties of excipients are retained in the combination, the only novelty is the improved functionality as compared with the same physical form. Their popularity in the pharmaceutical industry is still growing rapidly. In comparison with other novel excipients, CPEs do not require any toxicological study and can be considered safe if parent excipients are declared safe by the regulatory agencies. For CPEs, the safety assessment may only involve analytical studies to demonstrate that no new covalently bonded material was formed during coprocessing.
The aim of this research was to develop a co-processed excipient from starting physical mixture (microcrystalline cellulose, low-substituted hydroxypropyl cellulose, calcium phosphate- Fujicalin®). For this purpose, we used different technologies: Fluid Bed Technology, High Shear Mixer (HS), Twin Screw Extrusion (TSE), Spray Drying, and Direct compaction. In the process, we used purified water as granulation liquid. Investigation of physico-chemical properties of the physical mixer, reference materials, and develop co-processed materials was based on particle shape, particle size distribution, tap, bulk density, and flowability. Based on our research, Spray Drying has proven to be at least suitable, Fluid Bed less suitable while HS including TSE the most suitable technologies. Of both suitable technologies, we came to the discovery, that materials made from HS demonstrated unimodal and slim particle size distribution, while materials made from TSE demonstrated bimodal and wide particle size distribution. Furthermore, this was confirmed by the Span values, which were higher for TSE materials in comparison to HS materials, indicating a polydisperse system. The primary particles made with TSE were significantly larger, and asymmetrical than the corresponding particles made with HS technology which were smaller, more spherical, and had comparable flowability. Based on the overall results, we concluded, that the best method for co-processing was HS technology along with its designed manufacturing process to ensure a co-processed product with the desired physico-chemical and other properties.
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