CHEMICAL-STABILITY OF FLUOCINOLONE ACETONIDE OINTMENT AND FLUOCINONIDE CREAM DILUTED IN EMOLLIENT BASES

The chemical stability of fluocinolone acetonide ointment and fluocino nide cream was studied when diluted in emollient bases. Fluocinolone a cetonide ointment was diluted 1 in 4 with Unguentum Merck and Lipobase . Fluocinonide cream was also studied in these bases, with the additio n of Metosyn Diluent, at dilutions of 1 in 4 and 1 in 10. Regression a nalysis gave the time for 5% degradation of fluocinolone acetonide at a dilution of 1 in 4 in Unguentum Merck and in Lipobase as 12 weeks in both cases. The lower 95% confidence bound of each regression line wa s used to set shelf lives, for additional safety, and gave values of 1 month for the Unguentum Merck dilution and 2 months for the Lipobase dilution. Fluocinonide dilutions were more stable than the correspondi ng fluocinolone acetonide dilutions, with no degradation detectable du ring the study. The base made no observable difference to stability. S helf lives, based on the lower 95% confidence bound of the regression data, of more than 6 months would be feasible for all of the fluocinon ide 1 in 4 dilutions studied and for the 1 in 10 dilution in Unguentum Merck. However, for fluocinonide 1 in 10 in Metosyn Diluent, a shelf life of only 6 weeks could be assured, due to there being more variati on in the analytical results. There were insufficient data to determin e a storage life based on the lower 95% confidence bound of the regres sion for fluocinonide 1 in 10 in Lipobase. More data would be required to determine if there was significant interbatch variation in the sta bility of the dilutions.