Simulated Y-Site Compatibility of Vancomycin and Piperacillin-Tazobactam

To evaluate the physical compatibility of vancomycin with piperacillin-tazobactam during simulated Y-site administration.

Vancomycin and piperacillin-tazobactam were tested using 2 different diluents: 0.9% sodium chloride and 5% dextrose for injection. Vancomycin concentrations of 2, 5, and 10 mg/mL were tested using 0.9% sodium chloride and 4 and 8 mg/mL in 5% dextrose. Piperacillin-tazobactam was diluted to 16, 30, 40, 80, and 100 mg/mL, representing common concentrations used clinically in hospitals, and concentrations were tested in both 0.9% sodium chloride and 5% dextrose for injection. Medications were reconstituted under USP <797> aseptic technique. Combinations were tested in duplicate and reverse order with control solutions. Compatibility testing for Y-site included visual inspection, inspection with a high-intensity monodirectional light source (Tyndall beam), turbidimeter for turbidity evaluation, pH, and microscopic viewing. Testing occurred immediately after mixing, 15 minutes, 60 minutes, and 4 hours. If inconsistencies were observed between samples, testing was repeated to confirm results. Solutions were deemed incompatible if any one test failed and compatible if all tests were accepted.

When dextrose 5% for injection was used as the diluent, vancomycin 4 mg/mL was Y-site compatible with piperacillin-tazobactam 16, 30, and 40 mg/mL and incompatible with 80 and 100 mg/mL. Vancomycin 8 mg/mL was incompatible with all tested concentrations of piperacillin-tazobactam. When 0.9% sodium chloride was used as the diluents, Y-site compatibility was found with vancomycin 2 and 5 mg/mL and all tested concentrations of piperacillin-tazobactam. Vancomycin 10 mg/mL was incompatible with piperacillin-tazobactam 40, 80, and 100 mg/mL. Incompatibilities formed a white precipitate immediately on mixing.

Y-site incompatibility was greater for the tested concentrations of piperacillin-tazobactam and vancomycin when 5% dextrose was used as the diluent versus 0.9% sodium chloride. Y-site incompatibility was seen immediately in the form of a white precipitate on mixing.