Development of cycles for lyophilization

In order to find the freeze-drying cycle for the effective drying of a given biological entity or a material of biologic origin by sublimation of ice in vacuo, numerous time-consuming, trial and error preliminary studies have been required. Following a series of studies using different shelf temperatures, -30 degrees, -10 degrees, 0 degrees, +10 degrees and +20 degrees C, and elapsed times of 1,500, 2,000, 2,700, 4,000 and 5,500 minutes, plug characteristics and contents of residual moistures of freeze-dried 3 ml samples of 2% serum albumin were determined. Using the statistical method of least squares, geometric curves were fitted to the plot of times versus residual moistures for the several shelf temperatures. The equations for the fitted curves were used to construct a table showing the contents of residual moistures at 300 minute intervals. This table was used for developing successful drying cycles for several concentrations of serum albumin, dilute solutions of interferon, and serum containing HLA antibodies.