Comparison of the physicochemical properties of branded and generic glucose-added maintenance hypotonic infusion fluids to assess the potential for phlebitis and incompatibility with other drugs.

In Japan, the switch from branded to generic infusion fluids has been promoted as a national policy. Recently, as generic products have been in short supply, the switch from generic to branded infusion fluids has increased. However, certain additives for injectable infusion fluids, such as nonvolatile acids like acetic acid and hydrochloric acid, are not required to be listed in the package insert. We hypothesized that the addition of nonvolatile acids may be one of the reasons for the differences in physicochemical properties between the branded and generic infusion fluids. We have previously reported that in other types of electrolyte infusion fluids, a variation in pH can cause incompatibility with other drugs, and variation in titratable acidity and osmolality can lead to phlebitis. Glucose-added maintenance hypotonic infusion fluid (listed as type-3G) is commonly used as a maintenance solution when energy support is needed. However, nonvolatile acid is added to prevent the caramelization of glucose, resulting in higher osmolality and titratable acidity and lower pH. Therefore, we hypothesized that both phlebitis and incompatibility with other drugs are likely to occur; hence, we measured and evaluated the physicochemical properties of branded and generic type-3G infusion fluids. We show that the osmolality, pH, and titratable acidity of all evaluated branded and generic products differed significantly and that these properties should be evaluated together to avoid phlebitis and incompatibility with other drugs when switching between branded and generic type-3G infusion fluids.