Background When the brand name for piperacilline/tazobactam is out of stock, use of a generic product is required. But little chemical stability data are available for preparations of ready to use infusions by a centralised intravenous additive service (CIVAS).

Purpose To investigate the long term stability of a generic product of piperacilline/tazobactam in glucose 5% polyolefin bag after freezing, microwave thawing and final storage at 5 ± 3°C.

Material and methods 5 bags of 4 g of piperacilline/tazobactam Sandoz in 120 mL of glucose 5% were prepared under aseptic conditions and stored for 3 months at -20°C, and then thawed and stored for 58 days at 5 ± 3°C. Optical density measurement at different wavelengths, pH measurements and optic microscope observations were performed periodically during storage. A forced degradation test with HCl 12 M and NaOH 5 M before and after heating to 100°C was also performed. Concentrations were measured by high performance liquid chromatography—diode array detection, with a reversed phase column and a mobile phase (45% acetonitrile and 55% phosphate buffer, pH 3). Detection was made at 211 nm for tazobactam and 230 nm for piperacilline.

Results No significant changes in pH values or optic densities were seen during the study. No crystals were seen with the optic microscope. As recommended by the Food and Drug Administration (FDA), the 95% lower confidence limit of the concentration for the solutions remained greater than 90% of the initial concentration until 44 days of storage at 5 ± 3°C. Conclusion Under the conditions of this study, piperacilline/tazobactam Sandoz 4 g/120 mL of glucose 5% infusion in polyolefin bags remained stable for at least 44 days at 5 ± 3°C after freezing at -20°C and microwave thawing, and may be prepared in advanced by a CIVA.

References and/or Acknowledgements

1. Hecq JD, et al. Effects of freezing, long-term storage, and microwave thawing on the stability of piperacillin plus tazobactam in 5% dextrose for infusion. Can J Hosp Pharm 2004;5:276

References and/or AcknowledgementsNo conflict of interest.