Stability of a novel corticosteroid nasal irrigation solution: betamethasone 17-valerate added to extemporaneously prepared nasal irrigation solutions

Background

There are no commercially available nasal irrigation solutions containing corticosteroids. Instead, such preparations are extemporaneously prepared by adding existing corticosteroid formulations to nasal irrigation solutions. The stability of the corticosteroid betamethasone 17-valerate (B17V), in nasal irrigation solutions of different compositions and pH and stored under different temperatures, was studied to determine the optimal choice of solution and storage conditions.

Methods

Triplicate extemporaneous preparations made with B17V were prepared by adding a predetermined volume of B17V lotion to each nasal irrigation solution: normal saline (NS), sodium bicarbonate (NaHCO₃) powder dissolved in tap water, and a commercially available powder mixture (FLO Sinus Care Powder), dissolved in tap water or pre-boiled tap water. Preparations were stored at 30°C and 4°C. Sampling was carried out at 0, 1, 2, 6, and 24 hours. The concentrations of B17V and its degradation compound, betamethasone 21-valerate (B21V), were determined by high-performance liquid chromatography.

Results

Preparations stored at 30°C contained a lower amount of B17V and higher amount of B21V than those stored at 4°C. B17V stability in nasal irrigation solutions decreased in the following order: NS, FLO in fresh tap water, FLO in pre-boiled tap water, and NaHCO₃. The degradation rate of B17V increased with higher storage temperature and higher pH.

Conclusion

B17V is most stable when added to NS and least stable in NaHCO₃ solution. FLO solution prepared with either cooled boiled water or tap water is an alternative if administered immediately. Storage at 4°C can better preserve stability of B17V, over a period of 24 hours.

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