Exploring the application of single-step drying in lyophilization of high protein concentration formulations.

Objectives: Single-step drying integrates sublimation and desorption process in one step. The applicability of single-step drying in high protein concentration formulations with or without viscosity reducers remains to be explored. And drying behavior of single-step drying remains to be monitored.

Methods: Firstly, in formulations without viscosity reducers (sucrose and mannitol), the method of single-step drying at shelf temperature (Ts) of 25 °C and chamber pressure (Pc) of 0.3 mbar with aggressive annealing (-3 °C) was tested; secondly, two viscosity reducers (ArgHCl and NaCl) were applied to further explore the application of single-step drying in viscosity reducer-containing formulations; finally, drying behavior of single-step drying was monitored in real time by tunable diode laser absorption spectroscopy(TDLAS).

Results: In single-step drying process, significant cycle time reduction (68%) was achieved compared to traditional two-step drying. Good cake appearance was observed in all formulation combinations with comparable pre- and post-lyophilization quality attributes as well as reconstitution time. Three times faster sublimation rate was monitored in single-step drying process compared to traditional two-step drying.

Conclusion: Single-step drying was proved to be applicable to high protein concentration formulations with or without viscosity reducers. Significant cycle time reduction in drying process was achieved. Sublimation rate resulted in a more efficient drying cycle as a whole even though an increase of product resistance.