Stability of bortezomib 1-mg/mL solution in plastic syringe and glass vial

BACKGROUND: The proteasome inhibitor bortezomib (BTZ), used in antineoplastic chemotherapy, must be diluted in NaCl 0.9% for injection and stored for no more than 3 hours in a syringe or 8 hours in a vial. Better information on its stability could improve storage. OBJECTIVE: To assess the stability of BTZ solution (1 mg/mL) in syringes and vials. METHODS: BTZ 1-mg/mL solutions were prepared by adding sterile NaCl 0.9% to Velcade vials containing 3.5 mg of lophilized BTZ. Syringes were filled with 1 mL of solution and stored in the dark at 5 degrees C or 60 degrees C; others were not protected from light and stored at 22 degrees C. Velcade vials containing 1 mL of solution were stored at 5 degrees C in the dark. Samples were taken at various times over 23 days and assayed in duplicate. An HPLC method for assaying the stability of BTZ was validated. Appearance and pH were recorded. RESULTS: There was no color change or precipitation in the samples, and the pH was stable. Oxidation, light, and storage temperature all affected the chemical stability of BTZ. The mean concentrations of BTZ in syringes stored for 2, 3, and 5 days at 60, 22, and 5 degrees C were > 95% of the initial concentration. The mean concentration of BTZ in vials stored for 5 days at 5 degrees C was > 95% of the initial concentration. CONCLUSIONS: BTZ stored refrigerated in vials or syringes and protected from light is chemically stable for 5 days after reconstitution.