Evaluation of Sodium Benzoate Solution as Alternative Vehicle for Parenteral Diazepam

Abstract

This study attempts to evaluate sodium benzoate solution for its suitability as a substitute vehicle for parenteral diazepam, following reports of toxicity with propylene glycol, which is commonly used as the vehicle. A good parenteral vehicle, besides achieving a high solubility level of the drug should enhance or maintain the stability of the drug. Also, it must not show toxicity at the concentration used in product formulation. It should equally not affect the pharmacological response elicited by the drug an administration. In this study, the effects of sodium benzoate on the solubility, stability, haemolytic activity and pharmacodynamics of diazepam were investigated. Fifty milliliters each of sodium benzoate solutions ranging in concentration between 0.05M and 1.0M were dispensed in conical flasks and shaken with excess amounts of diazepam powder for 24 hours at different temperatures. The resulting dispersions were filtered and the filtrate assayed for diazepam at 311nm. The interaction between sodium benzoate and diazepam was studied by spectrometry, conductimetry, viscometry and densitometry. The stability of diazepam in the presence of sodium benzoate was studied at 400C, 500C and 600C.