Stability and surface activity of lactate dehydrogenase in spray‐dried trehalose

Abstract

The stability of the model protein lactate dehydrogenase (LDH) during spray-drying and also on subsequent dry storage was examined. Trehalose was used as a carrier. The spray-drying temperatures Tinlet and Toutlet have a measurable effect on LDH inactivation. Low Tinlet produced the least process inactivation, but gave a high residual moisture content making the protein's storage stability poor. High Tinlet reduced residual moisture and improved storage stability, but at the cost of high process inactivation. As already found for other systems, addition of a surfactant (in this case polysorbate 80) could ameliorate process inactivation of LDH at Tinlet = 150 degreesC. Surfactant had, however, a deleterious effect on storage stability of LDH, the vital factor being the molar ratio of surfactant/protein in the dried product. By using electron spectroscopy it was shown that LDH has a 10 times higher surface concentration in the dried trehalose particles than expected for a homogeneous distribution. Surface tension measurements at the water/air interface proved that LDH is surface active, although the Gibbs equation appeared to be inapplicable. Calculations of spray-droplet formation time and drying time indicate than the extent of diffusion-driven LDH adsorption to the liquid/air interface is sufficient to account for the measured amount of LDH inactivation during spray-drying. The presence of 0.1% polysorbate 80 to the spray solution prevents LDH from appearing at the surface of the dried particles. As a negative control, the phosphatide Lipoid E 80 does not prevent the appearance of LDH in the surface according to electron spectroscopy and does not therefore prevent LDH inactivation during spray-drying at Tinlet = 150 degreesC.

Stability of Protein Pharmaceuticals: An Update

“…For bulk powders, there have been a number of reports using spray drying (507)(508)(509)(510). These include formation of stable powders of IgGs (511,512) and hGH (513).…”

Systematic investigation of the effect of lyophilizate collapse on pharmaceutically relevant proteins I: Stability after freeze‐drying

“…Vacuum-and spray-drying, lacking the formation of a cake upon drying, have been successfully employed for protein stabilization. [23][24][25][26][27] Recently, the concept of foam drying was applied to stabilize proteins in the dried state. 28 Also, investigations by Abdul-Fattah et al 28 and by Hsu et al 29 indicate that a formulation with a smaller surface area might in certain cases be more stable.…”

Formation of Stable Submicron Protein Particles by Thin Film Freezing

“…However, the formation of stable submicron protein particles with surface areas exceeding 10 m 2 /g (4,18,19) is highly challenging, as the removal of water exposes protein molecules to large interfacial areas. Adsorption of protein at gas-liquid and ice-liquid interfaces often results in unfolding and aggregation (1,(18)(19)(20)(21)(22). In lyophilization, the most common process for producing stable protein particles, particle growth during slow cooling (∼1 K/min) limits the particle diameter to a minimum of a few microns with surface areas less than 1 m 2 /g (21).…”

“…Submicron protein particles may be precipitated from aqueous solution by a variety of processes including spraydrying (11,21,22,25), supercritical CO 2 -assisted aerosolization and bubble drying (scCO 2 A-BD) (26), spray freeze-drying (SFD) (1,18,19,21), and spray freezing into liquids (SFL). In SFD, an aqueous solution containing dissolved protein is atomized into the cold gas above a cryogenic liquid (18,19,(27)(28)(29).…”