Objectives This study was conducted to investigate the extended physicochemical stability of cabazitaxel containing premix solution and diluted infusion solutions in either 0.9% sodium chloride (NaCl) or 5% glucose (G5) vehicle solution.

Methods A stability indicating, reverse phase, high performance liquid chromatography assay with ultraviolet detection was developed and validated. Premix solutions of cabazitaxel were prepared in the original vials. Infusion solutions were prepared in prefilled polypropylene/polyethylene (PP/PE) infusion bags (0.9% NaCl, G5) to achieve the recommended minimum and maximum cabazitaxel concentrations (0.1 mg/mL, 0.26 mg/mL). Test solutions were stored refrigerated (2–8°C) or at room temperature (25°C), protected from light. Samples were taken and assayed in triplicate over a 28 day storage period. Physical stability was determined by measuring the pH value and visual inspection whenever samples for quantitative analysis were taken.

Results The premix solution containing cabazitaxel was found to be physicochemically stable over a period of 28 days. Diluted cabazitaxel infusion solutions remained chemically stable over a period of 28 days. Particulate matter of cabazitaxel was recognised in some infusion solutions after 21 days of storage.

Conclusions Cabazitaxel premix solutions and infusion solutions prepared with 0.9% NaCl or G5 vehicle solution in PP/PE bags are chemically stable over a storage period of 28 days, either refrigerated or stored at room temperature. However, unpredictable physical instability is to be regarded when expiration dates of diluted infusion solution are determined.