Silicone oil contamination of therapeutic protein formulations: Surfactant and protein effects

BIOT 227

John Gabrielson1, Daniel G. Bates1, Benjamin M. Williams1, Jean-Bernard Hamel2, John F. Carpenter, john.carpenter@uchsc.edu3, and Theodore W. Randolph, Theodore.Randolph@colorado.edu4. (1) Department of Chemical and Biological Engineering, University of Colorado, Boulder, Boulder, CO 80309, (2) Pharmaceutical Systems, BD Medical, 11, rue Aristide Berges, 38800 Le Pont de Claix, France, (3) Department of Pharmaceutical Sciences, University of Colorado Health Sciences Center, 4200 East 9th Avenue, Denver, CO 80262, (4) Department of Chemical and Biological Engineering, University of Colorado, Boulder, CO 80309
Purpose: Silicone oil has been shown under certain conditions, even at low concentrations, to induce protein aggregation. In addition to potential risk to patients, silicone oil induced therapeutic protein aggregation is a major concern in the pharmaceutical industry, potentially leading to loss of product and increased manufacturing costs. This study explores the complex interactions between silicone oil, therapeutic monoclonal antibody, and non-ionic surfactant in oil/aqueous emulsions. Methods: Medical grade polydimethylsiloxane (PDMS, or silicone oil) is added (0.01 – 10% v/v) to two aqueous buffering systems (10 mM sodium phosphate, 130 mM NaCl, pH 7.2; 10 mM sodium acetate, pH 5.0). Resulting suspensions are passed once through a high pressure homogenizer (Avestin, Inc., Emulsiflex C5 Homogenizer). Polysorbate 20 solution (Tween 20®, 0.002% - 2%) and Herceptin® (trastuzumab, 1 mg/mL) are added to the emulsion by repeated pipeting until fully mixed. Ultraviolet-visible and fluorescence spectroscopy, light scattering particle sizing, and fluorescence activated particle scanning are used for sample analysis. Results: Emulsion half-life is inversely proportional to silicone oil concentration. At pharmaceutically relevant silicone oil concentrations (< 10 µL/mL), emulsions are stable for many hours. Addition of the non-ionic surfactant, Tween 20®, further stabilizes the emulsions, particularly when the surfactant is added prior to homogenization. In the absence of Tween 20®, monoclonal antibody adsorbs to the oil surface, and acting as a surfactant, it moderately stabilizes the emulsion. As the size of oil-antibody conjugate particles increases, the ratio of adsorbed antibody to oil remains constant. Conclusions: In pharmaceutical formulations containing a non-ionic surfactant, presence of the surfactant may aid in the suspension and stabilization of oil droplets in aqueous buffer. Small oil droplets (ca. 1 µm) with adsorbed antibody may agglomerate to form larger, “multidroplet” particles.
 

Biophysical and Biomolecular Symposium: Protein Aggregation
3:00 PM-5:20 PM, Wednesday, August 22, 2007 BCEC -- 108, Oral

Division of Biochemical Technology

The 234th ACS National Meeting, Boston, MA, August 19-23, 2007