Category: Formulation and Quality
Purpose: Polysorbates are common excipients in drug formulations and function to stabilize therapeutic proteins by preventing adsorption at surface interfaces. Degradation of these excipients, by unintended chemical reactions or host cell esterases, could lead to instability of the drug formulation and subsequently cause quality, safety and efficacy concerns, including aggregation and immunogenicity of the therapeutic protein. Degradation of polysorbates in the presence of therapeutic proteins has been associated with sub-visible and visible particle formation. The formation of fatty acid particles appears dependent upon on the length of the fatty acid chain. We investigated how the fatty acid ester composition of polysorbate 80 effects particle formation and therapeutic protein stability when subjected to accelerated stress conditions.
Methods: Two different polysorbate 80-containing therapeutic monoclonal antibody formulations were reformulated with either polysorbate that is essentially pure in its oleic acid ester content or with compendial polysorbate 80 containing esters of oleic acid and other fatty acids with shorter chain lengths. Accelerated stress conditions, including esterase spiking, were then applied and changes to both the polysorbate and the therapeutic protein were monitored for stability, purity, and potency.
Results: The addition of esterase and storage at 37°C led to significant hydrolysis of the polysorbate ester and increases in particle formation for both ultrapure and heterogenous compendial polysorbates tested. The composition of polysorbate 80 did not appear to directly affect the stability of either therapeutic protein as measured by size exclusion chromatography or activity assays, but formulations prepared with compendial polysorbate 80 showed greater propensity for sub-visible particle formation when subjected to stress. We are currently studying specific changes in protein stability using orthogonal methods, including potency assays and chromatography methods to characterize the protein aggregates.
Conclusion: These results suggest that composition of fatty acids in polysorbate 80 may be important for sub-visible particulate formation under stressed conditions, but other endpoints require further evaluation.
Melissa Pegues– Silver Spring, Maryland
Karol Szczepanek– Silver Spring, Maryland
Mohamed Ghorab– Silver Spring, Maryland
Steven Wolfgang– Silver Spring, Maryland
Ashutosh Rao– Chief, Laboratory of Applied Biochemistry, U.S. Food and Drug Administration, Silver Spring, Maryland