High-Throughput Excipient Screening
The characterization information obtained from the empirical phase diagrams (EPD) is used to design high-throughput screening assays for the identification of potential stabilizers (Figure 1). The type of assay (e.g. light scattering for aggregation, fluorescence for tertiary structure change) is determined by the nature of the physical changes of the molecule and by the potential adaptation of the various assays to a microtiter plate format. The conditions for these assays are determined by the apparent phase boundaries of the EPD, as defined by the conditions of abrupt color change.
|High-throughput excipient screening assay development:
|Optimal Solution Conditions:
(pH, ionic strength)
Once the assays are established, a GRAS (generally regarded as safe) library is screened and potential stabilizers are determined. In collaboration with the KU High-Throughput Screening Laboratory, we also offer screening of larger libraries including the ChemBridge, ChemDiv, and Prestwick libraries.
The number and concentration of stabilizers is then optimized to ensure the highest degree of stability for the macromolecule. Individual techniques, usually CD and fluorescence, are repeated in the presence and absence of stabilizers to determine melting temperatures. Our goal is to obtain at least a 10- to 15-degree increase in the melting temperature in the presence of excipients, with complete elimination of aggregation under accelerated testing conditions.
Note: Add link to list of excipients
Joshi, SB., Bhambhani, A., Zeng, Y. and Middaugh, C. R. (2010) An Empirical Phase Diagram/High Throughput Screening Approach to the Characterization and Formulation of Biopharmaceuticals in “Formulation and Process Development Strategies for Manufacturing Biopharmaceuticals”, Jameel, F and Hershenson, S (editors), Wiley & Sons publication, p173-204.
Kamerzell, TJ, Esfandiary, R, Joshi SB, Middaugh, CR, Volkin, DB. (2011) Protein-excipient interactions: mechanisms and biophysical characterization applied to protein formulation development. Adv Drug Deliv Rev. 2011 Oct; 63(13):1118-59. PMID 21855584 http://www.ncbi.nlm.nih.gov/pubmed/21855584