Potential Sampling Errors in Stability Studies Due to Dead Volume in Closed System Transfer Devices

Closed system transfer devices (CSTD) help to reduce the exposure of healthcare professionals to hazardous drugs. They may be used in stability studies conducted on anticancer drugs. During a stability study about polyolefin bags of gemcitabine, Tevadaptor® device was suspected of causing a bias in the evaluation of the concentrations of the first aliquots extracted from the bags.

The objectives are to determine whether the use of a CSTD to prepare a drug solution and to withdraw it from a bag can interfere on the measured concentration compared to the expected one and to suggest hypothesis to explain the phenomenon.

In the first experiment, three polyolefin bags of gemcitabine (5.4 mg/mL) were prepared under aseptic conditions using the Tevadaptor Luer Lock Adaptor®. The day of preparation, five aliquots of 3.8 ml each were sequentially withdrawn from each polyolefin bag using the same device. After one day, a new aliquot was withdrawn from each bag. In the second experiment, three polyolefin bags of gemcitabine (5.4 mg/ml) were prepared under aseptic conditions using a needle. One aliquot was extracted using a needle after the preparation from each bag, and another aliquot was extracted after one day. The concentrations of all aliquots were measured by liquid chromatography coupled to a photodiode array detector during the same run.

The concentrations of the first aliquots extracted on day zero from the polyolefin bags using the Tevadaptor Luer Lock Adaptor® exhibit an overestimation of 26% ([95%CI: 23%-29%] P<0.001) compared to the others. Overestimation is not found for subsequent aliquots, or while using a needle to bypass the Tevadaptor® device.

This case highlights the bias that may arise when using CSTDs in stability studies. They should be used with comprehensive understanding of their technical specifications.