Stability and compatibility of binary mixtures of morphine hydrochloride with hyoscine-n-butyl bromide

The aim of this study was to determine the compatibility and stability of morphine hydrochloride and hyoscine-N-butyl bromide combined in solution at three different concentrations and stored in polypropylene syringes at 4°C and 25°C over a period of 15 days. The doses assayed were 20, 60 and 120 mg/day for morphine hydrochloride and 40, 60 and 80 mg/day for hyoscine-N-butyl bromide. These dose ranges were chosen according to daily practice. At both temperatures, all mixtures can be considered as physically compatible since no evidence of incompatibility—that is precipitation, turbidity, colour change or opacity and gas production—were observed. After 15 days of storage, the percentages of hyoscine-N-butyl bromide remaining in the drug mixtures tested ranged between 96.07% and 92.23%. At the end of the study, the percentages of morphine hydrochloride remaining in the drug mixtures were 100% at both temperatures.