Closed System Transfer Devices (CSTDs): Understanding Potential Over- and Under- Dosing of Liquid Vial Drug Products and How to Generally Mitigate.

Closed system transfer devices (CSTDs) are a major challenge for drug manufacturers to assess and assure drug compatibility and acceptable dosing accuracy for a range of clinical administration strategies. In this article, we systematically investigate parameters affecting the loss of product during transfer by CSTDs from vials to infusion bags. We show that liquid volume loss increases with vial size, vial neck diameter, and solution viscosity - while dependent on stopper design. We further compared CSTDs' performance with a traditional syringe transfer and learned that loss is larger for CSTDs than for syringe transfer. Based on experimental data, a statistical model was developed to predict drug loss upon transfer by CSTDs. The model predicted that, for single dose vials with USP<1151> conforming overfill, a complete extraction and transfer of the full dose can be assured for a broad range of CSTDs, product viscosities, and vial types (2R, 6R, 10R, 20R) if a flush (of syringe, syringe adaptor, bag spike) is performed. The model also predicted that complete transfer cannot be achieved for fill volumes ≤ 2.0 mL. For multi-dose vials and pooling of several vials, respectively, the effective dose transfer (i.e., ≥ 95%) for all CSTDs tested was predicted to be achieved if a minimum of 5.0 mL is transferred.

Assessment of net charge and protein-protein interactions of different monoclonal antibodies.

The purpose of this work was to compare biophysical properties of different monoclonal antibodies (mAbs). mAbs' theoretical isoelectric point (IEP) and theoretical net charge were compared with experimentally assessed values. IEP was determined by isoelectric focusing capillary electrophoresis, determination of zero electrophoretic mobility, or the minimum mutual diffusion coefficient during pH titration. Net charge was determined using electrophoretic mobility and self-diffusion coefficient. It was found that antibodies differ substantially in their biophysical properties, that is, in IEP, net charge, and zeta potential. Also, the importance of these properties was studied with respect to protein-protein interactions. This was achieved by assessing the second virial coefficient (A(2)) determined by static light scattering (SLS) and dynamic light scattering (DLS). It was found that at low ionic strength formulation conditions [20 mM histidine (His)/His-HCl buffer, pH 6.0] proteins' charge is the main driver for overall repulsive protein interactions. At high ionic strength conditions (20 mM His/His-HCl buffer, pH 6.0, + 150 mM NaCl), where counterions are shielding ionic interactions, proteins' repulsive forces were weakened, but to a different extent. Furthermore, a DLS method was developed allowing fast and easy assessment of A(2) by minimum need of material.