Recognition and identification of UV-absorbing leachables in EPREX pre-filled syringes: an unexpected occurrence at a formulation-component interface.

During the period of 1998 to 2002, there was an increase in the incidence of antibody-positive pure red cell aplasia (PRCA) in patients receiving subcutaneous administration of EPREX (epoetinum alfa). As part of the investigation of this event, the aqueous formulation containing polysorbate 80, introduced in 1998, facilitated the leaching of small-molecule, aromatic compounds from the uncoated rubber syringe stoppers. The leachables were identified using Liquid Chromatography-Mass Spectroscopy, Electrospray Ionisation-MS/MS, Dithiothreitol reduction, and Hydrogen/Deuterium exchange. The major leachable was identified as a dialkylphenol disulfide, and the majority of the remaining peaks were identified as structural variants containing different numbers of sulfur atoms in the sulfide bridge. In this report, we describe the strategies and experimental designs that were used to overcome the analytical challenges and that led to successful structural identification of the leachables in EPREX pre-filled syringes with uncoated syringe stoppers.