Stability Study of a 100 mg/mL Sodium Benzoate Solution in Water for Parenteral Use

Sodium benzoate is mainly used as a preservative in food and pharmaceuticals and as a treatment for hyperammonemia in urea-cycle disorders. It is typically diluted in 5 or 10% dextrose solutions for intravenous administration to patients. While the stability of oral and injectable sodium benzoate formulations has been studied, there is limited research on its stability as an injectable solution under International Council for Harmonisation (ICH) conditions.

This study evaluates the stability of a sodium benzoate injectable formulation in sterile water (100 mg/mL).

A 100 mg/mL sodium benzoate solution was prepared in sterile water. A highperformance liquid chromatography method with UV detection (HPLC-UV) was developed for dosage measurement. The solution was stored in sterile glass bottles at room temperature (25°C) and under refrigeration (5°C). The effects of plastic and rubber screw caps on stability were also assessed. Stability was monitored over 230 days using validated HPLC-UV methods, and microbiological assays were performed to ensure sterility per USP <797> and USP <81> standards, as required by the "Ordre des pharmaciens du Québec."

Sodium benzoate preparations in 10-mL horizontal and inverted glass bottles remained stable for at least 230 days at both storage conditions.

Sodium benzoate injectable preparations can be stored safely for 230 days at both room temperature and under refrigeration, maintaining efficacy and safety for intravenous patient administration. However, microbiological and endotoxin testing are necessary for each batch to ensure continued safety and effectiveness, according with the Quebec sterile production standard OPQ 2014.01.