THERMAL-STABILITY OF HUMAN-IMMUNOGLOBULINS WITH SORBITOL - A CRITICAL-EVALUATION

The effect of the additive sorbitol on the thermal stabilization of human IgG was investigated by differential scanning calorimetry and size exclusion chromatography. In the presence of 33% sorbitol, the temperature at which denaturation of IgG began (T-i) was increased from 52 to 65 degrees C. Similarly, the temperature of the maximum heat capacity (T-max) was increased from 69 to 76 degrees C. Sorbitol also decreased dimer aggregation and the extent of oligomerization during heating compared with IgG dissolved in phosphate buffer. Sorbitol at 33% prevented massive protein denaturation but a 10-15% of oligomerization of high molecular weight aggregates with turbidity could not be avoided when heating for 10 h at 60 degrees C. The use of sorbitol 33% to avoid heat denaturation of human IgG during viral inactivation did not prevent protein aggregation or the appearance of turbidity. Consequently, further processing will be required to achieve a product suitable for pharmaceutical use.