Purpose. The aim of the study was to investigate the effect of histidine on the stability and physical properties of a fully human anti-IL8 monoclonal antibody (ABX-IL8) in aqueous and solid forms.
Methods. Using a fractional factorial design, we tested many excipients, including histidine, sucrose, and other commonly used excipients, on the stability and physical properties of the antibody in both liquid and lyophilized forms. Antibody stability and physical properties were evaluated using size-exclusion high-performance liquid chromatography (SEC-HPLC), sodium dodecyl sulfate-polyacryla- mide gel electrophoresis (SDS-PAGE), and a viscometer. Residual moisture content was determined by coulometric Karl Fischer titrator. Differential scanning calorimetry (DSC) was used to detect the glass transition temperatures (Tg) of the solid cakes and melting temperatures (Tm) of the antibody in liquid formulations. Fourier-transform infrared (FTIR) spectroscopy was used to examine the overall secondary structure.
Results. Increasing the histidine concentration in the bulk solution inhibited the increases of high-molecular-weight (HMW) species and aggregates upon lyophilization and storage. In addition, histidine bulk enhanced solution stability of the antibody under freezing and thermal stress conditions, as evidenced by the lower levels of aggregates. Furthermore, histidine reduced viscosity of the antibody solution, which is desirable for the manufacture of the dosage form. However, high concentrations of histidine in liquid formulations led to coloration of the solution and high levels of aggregates on storage at elevated temperature (40°C) after the formulations were exposed to stainless steel containers during bulk freezing-thawing.
Conclusions. Histidine enhanced the stability of ABX-IL8 in both aqueous and lyophilized forms. Histidine also improved the physical properties such as reducing the solution viscosity. Liquid formulations containing high concentrations of histidine should not be stored in stainless steel tanks at elevated temperatures.