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

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.