Optimization and characterization of spray-dried IgG formulations: a design of experiment approach

BACKGROUND: The purpose of the present study is to optimize a spray-dried formulation as a model antibody regarding stability and aerodynamic property for further aerosol therapy of this group of macromolecules. METHOD: A three-factor, three-level, Box-Behnken design was employed milligrams of Cysteine (X(1)), Trehalose (X(2)), and Tween 20 (X(3)) as independent variables. The dependent variables were quantified and the optimized formulation was prepared accordingly. SEC-HPLC and FTIR-spectroscopy were conducted to evaluate the molecular and structural status of spray-dried preparations. Particle characterization of optimized sample was performed with the aid of DSC, SEM, and TSI examinations. RESULTS: Experimental responses of a total of 17 formulations resulted in yield values, (Y(1)), ranging from 21.1 ± 0.2 to 40.2 ± 0.1 (%); beta-sheet content, (Y(2)), from 66.22 ± 0.19 to 73.78 ± 0.26 (%); amount of aggregation following process, (Y(3)), ranging from 0.11 ± 0.03 to 0.95 ± 0.03 (%); and amount of aggregation upon storage, (Y(4)), from 0.81 ± 0.01 to 3.13 ± 0.64 (%) as dependent variables. Results—except for those of the beta sheet content—were fitted to quadratic models describing the inherent relationship between main factors. CONCLUSION: Co-application of Cysteine and Tween 20 preserved antibody molecules from molecular degradation and improved immediate and accelerated stability of spry-dried antibodies. Validation of the optimization study indicated high degree of prognostic ability of response surface methodology in preparation of stable spray-dried IgG. GRAPHICAL ABSTRACT: [Figure: see text]