Stability of 4 Intravenous Drug Formulations in Prefilled Syringes Stored Frozen for Up to 60 Days

Purpose: Prefilled drug syringe use may reduce the cost of routine antibiotic drug delivery. Storage of prefilled syringes frozen (-20°C) or refrigerated (4°C-5°C), can optimize the use of robotic syringe filling systems if acceptable stability data is gathered per USP 797 standards. Methods: Four intravenous (IV) drug formulations were prepared from bulk standard solutions and filled into 10 mL syringes using an Intellifill© IV Robot. Formulations were Piperacillin (2.0 g) and Tazobactam (0.25 g) as 2.25 g in 10 mL; Piperacillin (3.0 g) and Tazobactam (0.375 g) as 3.375 g in 10 mL; Cefuroxime as 1.5 g in 11 mL; and Vancomycin as 1.0 g in 10 mL. Concentrations were assayed at "zero time," and after 21, 45, and 60 days frozen. Syringes were warmed to room temperature (RT) by gently rolling in hands. Three syringes of each formulation were assayed by stability-indicating HPLC per USP procedures. Assay results are the average of 5 injections of samples from each syringe upon return to RT and repeated for 3 separate syringes maintained at RT for 24 hours. Results: All formulations were stable out to 60 days frozen. Both of the piperacillin/tazobactam formulations were also stable when kept at refrigerated temperature for 9 days. Conclusion: Piperacillin/Tazobactam formulations can be stored frozen (-20°C) for up to 60 days with no appreciable loss. Cefuroxime and Vancomycin formulations can be stored frozen for up to 60 days. Both Piperacillin/Tazobactam formulations can be refrigerated for up to 9 days. Implementation of larger batch compounding coupled with frozen syringe storage and delivery could result in enhanced uniformity of composition and significant manpower savings.