Compatibility and stability of morphine sulphate and naloxone hydrochloride in 0.9% sodium chloride for injection.

Background: Naloxone may be administered in conjunction with morphine to reduce the risk of opioid-induced pruritis. Combining these drugs for coadministration may be beneficial, but little is known about their physical compatibility and stability in combined solutions.

Objective: To describe the physical compatibility and stability of morphine sulphate and naloxone hydrochloride (at various concentrations) in IV admixtures.

Methods: The physical compatibility and stability of admixtures of morphine 1000 μg/mL and naloxone 4 μg/mL, 12.5 μg/mL, and 25 μg/mL in 0.9% sodium chloride were studied. For each concentration of naloxone, one bag was stored at room temperature (22°C) for 72 h and one bag was stored under refrigeration (4°C) for 30 days. For all preparations, physical characteristics, including pH, colour, and formation of precipitate, were evaluated. The samples were also analyzed by a stability-indicating high-performance liquid chromatographic method. Stability was defined as the retention of at least 90% of the initial concentration.

Results: No notable changes in pH or colour and no macroprecipitation were observed in any of the preparations after storage at 22°C for up to 72 h or at 4°C for up to 30 days. All preparations maintained more than 90% of the initial concentrations of morphine and naloxone at the end of the respective study periods. The calculated lower limit of the 95% confidence interval also indicated that 90% or more of the initial concentration remained at the end of each study period.

Conclusion: Admixtures of morphine sulphate and naloxone hydrochloride were stable for 72 h at room temperature and for 30 days with refrigeration.