Long-term Physicochemical Stability of Concentrated Solutions of Sodium Valproate in Polypropylene Syringes for Administration in the Intensive Care Unit

In some situations, drug solutions in higher concentrations are used in intensive care units. The objective of this study was to evaluate the physicochemical stability of concentrated solutions of valproate sodium in polypropylene syringes during 30 days at 5°C ± 3°C. Five syringes of 40 mL containing 20 mg/mL of sodium valproate in 0.9% sodium chloride were prepared and stored at 5°C ± 3°C during 30 days. Immediately after preparation and periodically during the storage, valproate concentrations were measured by high-performance liquid chromatography. Spectrophotometric absorbance at different wavelengths, pH measurement, and microscopic observations were also performed. All solutions were physically stable during the study period storage at 5°C ± 3°C. No color change, turbidity, precipitation, or opacity at visual observation was noticed. No significant pH variations or optic densities were observed. No crystals were seen by microscopic analysis. Concentrations of valproate remained stable during the period of storage. Solutions of sodium valproate 20 mg/mL in syringes of 0.9% sodium chloride were physically and chemically stable for at least 30 days when stored in syringes at 5°C ± 3°C. These solutions may be prepared in advance by a centralized intravenous additive service.