POWDER CHARACTERISTICS OF PROTEINS SPRAY-DRIED FROM DIFFERENT SPRAY-DRYERS

The powder characteristics of bovine somatotropin and casein spray-dri ed from laboratory, pilot and production spray-dryers were investigate d. The powder characteristics examined included particle size distribu tion and morphology; bulk density; and flowability as measured by angl e of repose, compressibility index and shear cell indices. Morphology classification showed internal voidage, blowholes, expanded, smooth an d folding for somatotropin and casein spray-dried from the various spr ay-dryers. Particle size distributions of the bovine somatotropin and casein were unimodal and skewed. As the drying-chamber size of the spr ay-dryer increased, the particle sizes of both somatotropin and casein increased from mean volume diameters of 6-8 mu using the laboratory a nd pilot spray-dryers to 13-24 mu when using the production size spray -dryers. Spray-dried bovine somatotropin and casein had bulk densities of 0.090 to 0.195 g/cm(3). Three flowability tests showed casein and somatotropin spray-dried from the different spray-dryers exhibited poo r flow which could result in pharmaceutical manufacture challenges, Th e morphology and flowability of the two spray-dried proteins remained the same when comparing material produced from all four spray-dryers. However, the mean volume diameter, particle size distribution and bulk density did vary which might change critical product characteristics during scale-up. In general, similar morphology, particle size distrib utions, flowability and bulk densities were observed when comparing sp ray-dried casein and bovine somatotropin produced from the same model spray-dryer. Casein is recommended as a model protein for powder chara cterization during spray-drying and early formulation manufacture proc ess development when adequate quantities of the recombinant protein ar e not available.