AIM To investigate release characteristics
in vitro under 4 different pH conditions of 2 commercial
mizolastine sustained
release tablets and to compare their difference.METHODS The release tests were carried out with rotating basket method.The accumulative release percent under different pH conditions of 2
formulas was calculated,the accumulative release curves were made and the Weibull's equation was used to fit the data.The release parameters such as t_(50),t_d and m were statistically analyzed by variance analysis and t test.Meanwhile time-release-pH three dimensional release curves were made and the difference of release in vitro between the 2 formulas was compared by f_2 fit factors method.RESULTS In 4 medium with different pH values,t_(50) and t_d of formula A are smaller than those of formula B and the difference has significant meaning(P<0.01).The f_2 value is 54.36,51.84,50.77 and 49.17 in the medium with pH 1.0,4.0,6.8 and distilled water,respectively.CONCLUSION The release characteristics of the 2 formulas in vitro vary with different pH values.Under 4 different pH conditions,the release rates of formula A are more rapid than those of formula B before 2 h,which could be the basis for clinical use.