In Vitro Assessment of Vancomycin HCl Compatibility after Coinfusion with a Specialized Amino Acid Formulation

Vancomycin usage at British Columbia's Children's Hospital has increased substantially in the Special Care Nursery as a consequence of a study demonstrating a reduced morbidity and mortality in neonates with necrotizing enterocolitis when treated with vancomycin and cefotaxime. The inability to place more than one peripheral intravenous access necessitates interruption of parenteral nutrition to infuse vancomycin, resulting in a reduction of the planned daily intake of these neonates. This is clinically significant with the administration of vancomycin because of the long administration period required for this drug (60 minutes). This study was designed to assess the physical and chemical stability of vancomycin with a standard neonatal parenteral nutrition solution, Vamin A, when coadministered through the same intravenous line. To simulate the actual clinical setting, the dose of vancomycin and the infusion rate of Vamin A were chosen to represent those commonly used in a 1-kg neonate. Physical compatibility was assessed using effluent obtained after coinfusion of vancomycin with parenteral nutrition solution. Duplicate samples were visually checked for color changes and precipitate. High-pressure liquid chromatography (HPLC) and pH testing were used to assess chemical compatibility of vancomycin. The results of physical compatibility revealed no color change or precipitate. No changes in pH were observed. HPLC determination confirmed that there were no significant time-dependent changes in vancomycin stability. The samples were studied over 24 hours to determine the rate of degradation of vancomycin, if any, under various temperature conditions. The concentrations were not significantly different from each other at the different temperatures studied. Thus, there was no apparent change in the concentration of vancomycin in the presence of Vamin A. The results support the findings observed in other studies, which indicate that vancomycin is compatible when coinfused with Vamin A parenteral nutrition solution. It is concluded that vancomycin can be safely coinfused via four-way stopcock with Vamin A in those neonates in whom no other intravenous access can be obtained. The benefits of coinfusion include (1) maintenance of planned daily intake for the neonate, (2) a decrease in nonnutrient fluid intake, and (3) a decrease in nursing time for line manipulation. (Journal of Parenteral and Enteral Nutrition 15:536-539, 1991)