Stability study of human serum albumin pharmaceutical preparations

The influence of temperature on the stability of human serum albumin (HSA) pharmaceutical preparations has been studied by size-exclusion high-perform ance liquid chromatography with multi-angle laser-light-scattering detectio n and by particle-size analysis. The behaviour of HSA in two pharmaceutical preparations stored at different temperatures (40, 55 and 70 degrees C) followed the same pattern-an increa se in the relative percentage of dimer (MW 132 000 Da) and aggregate (MW > 200 000 Da), and then a decrease in the concentration of all species and, f inally, sudden protein coagulation. These results suggest a time- and tempe rature-dependent process. At 70 degrees C, monomer only was detected for bo th preparations; the amount remaining was 83 and 72% for formulations A and B, respectively. Analysis of size-distribution curves also seems to confir m these results. Initially, three distributions were observed with length-v olume mean diameters (d(l,v)) of 1.67, 10.6 and 57 mu m. After 80 days at 5 5 degrees C, only two distributions were observed, with d(l,v) of 3.07 and 76 mu m. An additional study using pure HSA at different concentrations (0. 3, 2.5, 5 and 10% w/v) and storage at 75 degrees C was performed to determi ne the influence of the concentration of auxiliary substances and of the HS A. Only when the HSA concentration was 0.3% w/v did the remaining fraction of HSA fit a Prout-Thompkins nucleation model. Initially three distribution s with mean sizes of 2, 20 and 40 mu m were observed whereas at the end of the assay only one distribution, mean size 129 mu m, was seen. The methodol ogy used enabled us to separate the HSA degradation products and to determi ne the absolute molecular weight of albumin monomer and dimer. It is possible to conclude that the degradation mechanism for the formulati ons studied is complex, and that it is possible to fit the degradation data to Preut-Thompkins kinetics only when the concentration of HSA is low enou gh (0.3% w/v).