CHemical stability and compatibility study of vancomycin for administration by continuous infusion in intensive care units

In this study, various analytical techniques were applied in order to investigate the feasibility of continuously infusing vancomycin in intensive care units. First, the chemical stability of a 40 mg=mL vancomycin solution in normal saline was studied. The stability study included pH measurement, visual inspection, UV spectrophotometry, and assay by capillary electrophoresis. Subsequently, physical and chemical compatibility of vancomycin with five commonly co-administered drugs was evaluated. Physical compatibility tests consisted of pH measurement, visual inspection, and nephelometry. Physically compatible drugs were further assessed for chemical compatibility with vancomycin, by determining the vancomycin content in mixed samples using capillary electrophoresis. No changes in physical characteristics of the vancomycin solution were observed during 24 hours. The content of vancomycin remained higher than 90% of the nominal concentration throughout the stability study. Addition of sodium valproate and dipotassium clorazepate to the vancomycin solution resulted in precipitation. Vancomycin was physically compatible with amiodarone, piritramide and midazolam, respectively. Furthermore, capillary electrophoretic analysis revealed no decrease in vancomycin content upon mixing with physically compatible drugs. In conclusion, a 40 mg=mL vancomycin solution was proven to be stable and compatible with midazolam, piritramide, and amiodarone. Sodium valproate and dipotassium clorazepate, however, were physically incompatible with vancomycin.