These two degradation products are not detectable with the chromatographic EX 527 molecular weight method used to assay busulfan. This hydrolysis will contribute to the decrease in the busulfan content of preparations over time. However, in this study, we demonstrated that another phenomenon could be the main cause of the decrease in the busulfan content, namely precipitate formation. Precipitation is a phenomenon that

is unpredictable and difficult to control, and a JNK-IN-8 number of factors may be involved, particularly container/content interactions as described by Karstens and Krämer [11], temperature, or agitation. So the explanation could be that on one hand there is more agitation of PVC bags and glass bottles than of PP syringes, and on the other hand a higher temperature can promote interactions between the roughness of the container (especially glass) and the content responsible for precipitation. Our study enabled a clearer understanding of this decrease. The initial rapid decline in busulfan content may be due to precipitation, since treatment

of early samples with DMA to dissolve any precipitated busulfan resulted in content levels greater than 95 % of the starting levels. Hydrolysis appears to be involved in the subsequent decline in busulfan content. Reviewing our results, some discrepancies rise, such as that between the 15- and 48-h series measurements. The precipitation phenomenon was attributed as the factor that led to discrepancies, given that the AC220 busulfan solution was

assessed and did not include the precipitate (which may have contained some busulfan). Furthermore, some samples were precipitated and some were not. When examining filipin the pH of the solutions, our results demonstrated higher initial pH values in the PVC bags, and it is thought that this may have arisen via chemical interaction between DMA and the material of the bag. Higher initial osmolarity values were also noted in the PVC bags, which may confirm the potential pH variations observed in the PVC bags. 5 Conclusions Of the containers studied, PP was the material allowing the longest period of stability for busulfan solutions diluted to a 0.55 mg/mL concentration. The longest periods of stability were obtained for solutions placed at 2–8 °C, regardless of the container. This study allowed us to understand the decrease of the busulfan content. With hydrolysis degradation, the precipitation phenomen is responsible for busulfan solutions’ instability. This phenomen affects other drugs such as fungizone, cytarabine (according to the diluent), or etoposide, according to the concentration. For busulfan, precipitation appears to be temperature related; as the storage temperature increased, the stability of the dilute solutions decreased. Acknowledgments This study was made possible by the provision of the product by Pierre Fabre Laboratories. We thank Rod McNab, PhD, of inScience Communications, Springer Healthcare, who provided copy editing and journal styling prior to submission.