Impact of process stress on protein stability in highly-loaded solid protein/PEG formulations from small-scale melt extrusion

Micro-Scale Vacuum Compression Molding as a Predictive Screening Tool of Protein Integrity for Potential Hot-Melt Extrusion Processes

“…In the case of human insulin-loaded PLGA and PEG 20,000 discs, the process of VCM led to slight changes in secondary structure elements independent of the applied processing times. As discussed in a previous work, the conformational stability of lysozyme was not negatively affected by HME processing [ 10 ]. The FT-IR spectra of lysozyme-loaded PEG-extrudates produced by ram extrusion or twin-screw extrusion (TSE), as described by Dauer et al [ 10 ], were comparable to the native lysozyme powder used to prepare the physical mixture and thus the extrudates.…”

“…We used DSC for analyzing the protein unfolding temperature in solid-state after VCM and compared it to unprocessed samples. DSC presented unfolding temperatures of native lysozyme, BSA, and human insulin as 204.7 °C, 218.2 °C, and 213.1 °C, respectively ( Figure 1 ), which served as reference values [ 10 ]. The DSC thermograms of protein powder, pure polymers, physical mixtures composed of 20% protein powder and 80% polymer, and 20% protein-loaded discs are shown in the Supplementary Materials ( Figures S1–S3 ).…”

“…The stabilization of proteins can be achieved by embedding the protein or peptide powder in eroding or dissolving polymer matrices by scalable formulation technologies such as hot-melt extrusion (HME), freeze-drying (FD), or spray-freeze drying (SFD) [ 7 , 8 , 9 ]. HME was introduced with increasing awareness in several works as a manufacturing tool for the production of solid protein formulations, for instance, as a solid-state stabilization approach or for the development of long-term release systems for parenteral administration (e.g., protein-loaded implants) [ 8 , 10 , 11 , 12 ]. The use of HME provides a variety of motives for the formulation of long-term delivery systems: (i) no use of organic solvents, (ii) high drug loadings in polymeric matrices are feasible, (iii) simple scale-up, and (iv) use of additional excipients such as surfactants are not mandatory [ 13 , 14 ].…”

“…The use of HME provides a variety of motives for the formulation of long-term delivery systems: (i) no use of organic solvents, (ii) high drug loadings in polymeric matrices are feasible, (iii) simple scale-up, and (iv) use of additional excipients such as surfactants are not mandatory [ 13 , 14 ]. Different types of polymers can be simply used to embed proteins or peptides in a matrix for solid-state stabilization and optimizing the protein release behavior by HME processing [ 8 , 10 ]. Furthermore, the used polymers can ensure the stable folded structure of a protein or peptide during the HME process due to an immobilization of active biomolecules in the polymeric matrix [ 15 , 16 ].…”

“…In a previously described study, we presented a sensitive characterization pathway of protein stability focused on the characterization of protein-loaded extrudates at a high drug load (i.e., >40%) prepared by ram extrusion and twin-screw extrusion (TSE). Here, changes in protein stability affected by thermomechanical stress during the extrusion process were investigated [ 10 ]. Although small-scale HME leads to high yields of an extruded powder mixture, the process is still associated with a moderate material input (i.e., >2 g of the powdered protein-polymer mixture) and material loss (e.g., <0.5 g of the protein-polymer mixture due to gaps between the rotating screws in TSE processing).…”