Compaction Properties of Particulate Proteins in Binary Powder Mixtures with Common Excipients

The increasing interest in protein- and peptide-based oral pharmaceuticals has culminated in the first protein-based products for oral delivery becoming commercially available. This study investigates the compaction properties of proteins in binary mixtures with common excipients up to 30% (w/w) of particulate protein. Two model proteins, lysozyme and bovine serum albumin, were compacted with either microcrystalline cellulose, spray-dried lactose monohydrate, or calcium hydrogen phosphate dihydrate at two different compaction pressures. Compared to the compacted pure materials, a significant increase in the tensile strength of the compacts was observed for the binary blends containing lysozyme together with the brittle excipients. This could be attributed to the increased bonding forces between the particles in the blend compared to the pure materials. The use of bovine serum albumin with a larger particle size resulted in a decrease in tensile strength for all the compacts. The change in the tensile strength with an increasing protein content was non-linear for both proteins. This work highlights the importance of considering the particulate properties of protein powders and that protein-based compacts can be designed with similar principles as small-molecules in terms of their mechanical tablet properties.