Physical and chemical compatibility of intravenous metronidazole infusion with physiological solutions: UV-Visible Spectroscopy study

Background and Objectives: The instructions of the manufacturer showed that metronidazole infusion solution (5mg/mL) is incompatible with few drugs. This study aimed to determine the physical and chemical compatibilities of metronidazole infusion with commonly used intravenously administered physiological solutions. Methods: Metronidazole injection in a commercially available concentration of 5mg/mL was mixed with 0.9% sodium chloride, 5% glucose saline or Ringer's solution in the infused bottle or during simulated Y-site injection. metronidazole was examined physically by visual inspection and chemically by ultraviolet-visible spectrophotometer analysis. Adsorption of metronidazole to intravenous administration sets without inline filters was also studied. Furthermore, the compatibility of metronidazole with some drugs related to beta-lactams was studied. Physical incompatibility was determined by visual inspection against a black-andwhite background, and chemical incompatibility was measured by a stability-indicating UVvisible spectrophotometer assay for metronidazole. Results: The absorbance magnitude (O.D.) recorded by UV-visible spectrophotometer showed differences in respect to the infused solutions as well as to the admixed physiological solutions. Moreover, metronidazole is incompatible with Co-amoxicillin and clavulanic acid, and cefepime. . Conclusions: It is concluded that metronidazole infusion should be separately infused, not admixed with physiological solutions and avoided its combination with beta lactams.