BACKGROUND: This study aimed to investigate the stability and compatibility of a mixture of hydromorphone hydrochloride, bupivacaine hydrochloride, and dexamethasone sodium phosphate in 0.9% sodium chloride for intrathecal injection.

MATERIAL AND METHODS: Drug mixtures were prepared under simulated clinical conditions and stored in an intrathecal infusion pump at 4°C, 25°C, or 37°C for 20 days. Color, visible particles, and pH of the solution mixtures were assessed at each time point to evaluate physical compatibility. The concentrations of each component were measured at 0, 1, 3, 5, 7, 9, 11, 13, 15, and 20 days using a validated high-performance liquid chromatography method.

RESULTS: The solutions remained clear and colorless, without precipitation or turbidity. The pH values of the admixtures ranged from 5.52 to 6.23 at 4°C, from 5.71 to 5.93 at 25°C, and from 5.42 to 6.19 at 37°C over 20 days. The concentrations of all analytes remained greater than 98.0% of the initial values at all 3 temperatures throughout the 20-day period.

CONCLUSIONS: Admixtures of hydromorphone hydrochloride, bupivacaine hydrochloride, and dexamethasone sodium phosphate in 0.9% sodium chloride at the studied concentrations were physically and chemically stable for up to 20 days when stored at 4°C, 25°C, or 37°C in an intrathecal infusion pump.

Keywords: Dexamethasone, Drug Stability, High Pressure Liquid Chromatography, Hydromorphone, Pharmaceutical Chemistry