Background Bortezomib is used in the treatment of myeloma. The manufacturer gives a 8 h stability in syringes and André et al (Ann Pharmacother 2005; 39: 1462-1466) gives a 5 days at 5°C.

Purpose The objective was to evaluate the stability of a 1 mg/ml solution stored over 35 days in polypropylene syringes in order to prepare in advance standardised doses without any risk of losing the syringes if the administration is cancelled.

Materials and methods Four syringes were prepared after reconstitution of 3.5 mg of bortezomib with 3.5 mL 0.9% sodium chloride. Two were stored under refrigeration (2-8°C) and two at room temperature. Criteria of stability were defined as retention of at least 95% of the initial drug concentration and as percentage of degradation products below 1%. After a visual inspection, samples of each syringe were analysed after preparation and on days 2, 4, 7, 14, 21, 28, 35 with a stability-indicating high-performance liquid chromatography validated method according to ICH guidelines

Results No physical changes were observed during the study period. Under refrigeration, solution retained over 95% of the initial bortezomib concentration until day 35. Three degradation products appeared, corresponding to 0.4% of total peaks areas. At room temperature, the bortezomib concentration stayed over 95% until day 28, and six products of degradation reached 3% at day 35. Solutions of bortezomib 1 mg/ml in 0.9% sodium chloride were stable for 35 days at 2-8°C and for 14 days at room temperature.

Conclusions Stability for 35 days at refrigerated storage (2-8°C) enables a new organisation of the Centralised Unit in our pharmacy and allows the preparation of syringes in advance, in standardised doses without any risk of losing money, because of the possible conservation and reallocation of a syringe which injection would be cancelled. The immediate availability reduces considerably the waiting time of the patient in the wards.