Use of poloxamer polymers to stabilize recombinant human growth hormone against various processing stresses.

Several processing and shipping stresses were investigated for their effect on the physical stability of recombinant human growth hormone (rhGH). These included exposure to air/water interfaces, adsorption to hydrophobic surfaces, freeze-thaw cycles, and temperature. The interfacially and thermally denatured hormone was evaluated for the presence of insoluble and soluble aggregates by spectrophotometry and by size-exclusion chromatography, respectively. Noncovalent aggregates were generated by either vortexing or multiple passages through a hypodermic needle, processes which exposed the protein to air/water interfaces. Thermal stress also resulted in the generation of aggregates. This aggregation was reduced or eliminated by the use of poloxamer polymers. Under the conditions employed, filtration through some commercially available filters, exposure to hydrophobic beads, or multiple freeze-thaw cycles did not produce any aggregates within the limitations of the analytical procedures used. Based on this study, Poloxamer 407 was found to be the most effective stabilizer for rhGH for protection against interfacial and thermal stress.