Development of a multidose formulation for a humanized monoclonal antibody using experimental design techniques.

The purpose of this study was to identify optimal preservatives for a multidose formulation of a humanized monoclonal antibody using experimental design techniques. The effect of antimicrobial parenteral preservatives (benzyl alcohol, chlorobutanol, methylparaben, propylparaben, phenol, and m-cresol) on protein stability was assessed using size-exclusion chromatography, differential scanning calorimetry, right-angle light scattering, UV spectroscopy, and potency testing using a cell-based fluorescence-activated cell sorting method. A quick, cost-effective preservative screening test was designed. Combinations of preservatives were examined using an I-optimal experimental design. The protein was most stable in the presence of methylparaben and propylparaben, and was compatible with benzyl alcohol and chlorobutanol at low concentrations. Phenol and m-cresol were not compatible with the protein. The I-optimal experimental design indicated that as an individual preservative, benzyl alcohol was promising. The model also indicated several effective combinations of preservatives that satisfied the antimicrobial efficacy and physical stability constraints. The preservative screening test and the experimental design approach were effective in identifying optimal concentrations of antimicrobial preservatives for a multidose protein formulation; (1) benzyl alcohol, and (2) the combination of methylparaben and chlorobutanol were screened as potential candidates to satisfy the regulatory requirements of various preservative efficacy tests.