Stability of aseptically prepared tazocin solutions in polyvinyl chloride bags.

BACKGROUND Tazocin, a mixture of piperacillin and tazobactam, has recently been reformulated to include edetate disodium (EDTA) and citric acid. Since the introduction of this new formulation, there have been no studies of stability in polyvinylchloride (PVC) bags. OBJECTIVE To complete a physical compatibility and chemical stability study of the new formulation of Tazocin, prepared at 2 concentrations in each of 2 diluents and stored in PVC bags. METHODS Tazocin, at 22.5 or 90 mg/mL, was compounded in dextrose 5% in water (D5W) or 0.9% sodium chloride (normal saline [NS]) in PVC bags. The bags were stored at 5°C with protection from light for 14, 21, or 28 days, followed in each case by storage at 23°C with exposure to light for 72 h. Triplicate samples collected at each of the 7 time points were analyzed in duplicate using a stability-indicating high-performance liquid chromatography method. Physical compatibility was determined by monitoring the solutions for changes in colour, clarity, and pH. RESULTS The amount of each drug remaining for each concentration in each diluent was above 95% of the initial concentration after storage at 5°C with protection from light and above 94% of the initial concentration after an additional 72 h at 23°C with exposure to light. The pH of the solutions changed only slightly over the course of the study, and all solutions remained clear and colourless. CONCLUSIONS Tazocin solutions at 22.5 and 90 mg/mL, prepared in PVC bags of either D5W or NS, were chemically stable after storage for up to 28 days at 5°C with protection from light followed by 72 h at 23°C with exposure to light.