Chemical Stability of Plerixafor after Opening of Single-Use Vial.

Background: The addition of the immunostimulant plerixafor to the current standard-of-care regimens of granulocyte colony-stimulating growth factor with or without chemotherapy has improved clinical results in terms of successful stem cell mobilization and the outcomes of stem cell transplant in various settings. With this medical innovation has come an added financial cost for institutions where stem cell transplants are routinely performed, and there may be a further financial burden when the contents of partial vials of the drug are wasted, given that plerixafor vials (Mozobil, Sanofi-Aventis Canada Inc) are currently deemed suitable only for single use.

Objective: To determine whether the portion of plerixafor remaining in an opened vial of the Mozobil product after administration of a single dose is chemically stable, by comparison with the original product.

Methods: Stability testing of partial drug contents of an opened vial, stored at room temperature or under refrigeration (4°C), was conducted using liquid chromatography-tandem mass spectrometry analysis. The mean concentration of plerixafor (μmol/L), standard deviation, coefficient of variation, and bias were determined on days 2, 3, 11, 17, 24, and 31. Method validation included determination of precision, sensitivity, recovery, dilution linearity, and carryover.

Results: Throughout the 4-week testing period, measured plerixafor concentration in aliquots stored at room temperature and under refrigeration, tested in series over time, appeared similar. The mean residual drug concentration after initial opening was slightly, but not significantly, higher for the sample designated for storage at room temperature than the one designated for refrigerated storage (40.4 versus 39.9 μmol/L; = 0.37).

Conclusions: Residual plerixafor after initial opening of a vial of the Mozobil product remained chemically stable for at least 2 weeks both at room temperature and under refrigeration. The results of this study provide in vitro evidence to support multiple uses, instead of single use, of vials of this drug in an aseptic, controlled environment.