How subvisible particles become invisible-relevance of the refractive index for protein particle analysis.
PMID 23463514 · Journal of pharmaceutical sciences · 2013 · DOI 10.1002/jps.23479
Authors: Sarah Zölls; Manuel Gregoritza; Ruedeeporn Tantipolphan; Michael Wiggenhorn; Gerhard Winter; Wolfgang Friess; Andrea Hawe
Abstract
The aim of the present study was to quantitatively assess the relevance of transparency and refractive index (RI) on protein particle analysis by the light-based techniques light obscuration (LO) and Micro-Flow Imaging (MFI). A novel method for determining the RI of protein particles was developed and provided an RI of 1.41 for protein particles from two different proteins. An increased RI of the formulation by high protein concentration and/or sugars at pharmaceutically relevant levels was shown to lead to a significant underestimation of the subvisible particle concentration determined by LO and MFI. An RI match even caused particles to become "invisible" for the system, that is, not detectable anymore by LO and MFI. To determine the influence of formulation RI on particle measurements, we suggest the use of polytetrafluoroethylene (PTFE) particles to test a specific formulation for RI effects. In case of RI influences, we recommend also using a light-independent technique such as resonant mass measurement (RMM) (Archimedes) for subvisible particle analysis in protein formulations.
Antibodies, Monoclonal; Antibodies, Monoclonal, Murine-Derived; Etanercept; Humans; Immunoglobulin G; Infliximab; Light; Particle Size; Receptors, Tumor Necrosis Factor; Refractometry; Rituximab; Scattering, Radiation; Serum Albumin
Cite
Sarah Zölls; Manuel Gregoritza; Ruedeeporn Tantipolphan; Michael Wiggenhorn; Gerhard Winter; Wolfgang Friess; Andrea Hawe. How subvisible particles become invisible-relevance of the refractive index for protein particle analysis. Journal of pharmaceutical sciences (2013). PMID 23463514. DOI 10.1002/jps.23479.