Opalescence of an IgG1 Monoclonal Antibody Formulation is Mediated by Ionic Strength and Excipients - Can increase in ionic strength result in higher viscosity? - BioPharm International

ADVERTISEMENT

Opalescence of an IgG1 Monoclonal Antibody Formulation is Mediated by Ionic Strength and Excipients
Can increase in ionic strength result in higher viscosity?


BioPharm International
Volume 22, Issue 4

in which NA is Avogadro's constant (mol-1), λo is the Laser wavelength (cm), no is the solvent refractive index, and dn/dc is the the differential refractive index increment (cm3 g-1).

For particles that are smaller than the incident light (laser) used to measure the particle size, Equation 1 can be reduced to the linear form shown in the following:13




(Equation 2)

RESULTS

Visual Observations


Figure 1
MAb1 in a liquid formulation consisting of 24 mg/mL of IgG1 in a buffer, 150 mM NaCl, and PS-80, pH 6.0 in glass vials was inspected visually at 25 C and was determined to be opalescent (Figure 1). The MAb1 formulation was equivalent to a Reference III standard [18–30 nephelometric turbidity units (NTU)] according to the EP (5.0, 2.2.1, Clarity and degree of opalescence of liquids). Following filtration of MAb1 through a 0.22-μm sterilizing filter, the opalescence remained unchanged, indicating it was not caused by insoluble aggregates (data not shown).

Particle Size


Figure 2
The particle size of MAb1 was evaluated beginning at a concentration of 20 mg/mL of IgG1 in a buffer, 150 mM NaCl, and PS-80, pH 6.0 in glass vials and was diluted in the same formulation to approximately 1 mg/mL (Figure 2). It was determined that MAb1 had a larger apparent hydrodynamic radius at higher concentrations, and that it decreased as the formulation was diluted.


Figure 3
SEC–HPLC was then performed on MAb1 at a concentration of 1 mg/mL. It was determined that the sample was mostly monomeric (>99%), with a small amount of dimer present (~1%) (Figure 3). In independent experiments, it was demonstrated that IgG monomers have a retention time of approximately 16 to 19 min on a TSKgel 3000SWXL column (data not shown).


blog comments powered by Disqus

ADVERTISEMENT

ADVERTISEMENT

New Tax Rules May Deter Future Pharma M&A
October 1, 2014
NIH Seeks to Improve Vaccine Response with New Adjuvants
September 30, 2014
New Report Details Players and Pipelines in the Biosimilar Space
September 30, 2014
Baxter International Plans to Open R&D Center for Baxalta
September 30, 2014
FDA Releases First-Ever Purple Book for Biosimilar Characterization
September 26, 2014
Author Guidelines
Source: BioPharm International,
Click here