Mahmoud M. Ghorab, Yasser S. El-Saharty, Amna A. Makky and Shaimaa M. Badr-Eldin*
This work aimed to formulate sildenafil citrate rapidly disintegrating tablets with enhanced stability utilizing the approach of incorporating antioxidant simultaneously with pH modifier for adjusting the tablet microenvironmental pH. Studies for effect of pH on the drug saturated solutions stability revealed that the drug exhibited maximum stability at pH 4.6. Studies for the effect of antioxidants on drug stability revealed marked stabilizing effect of sodium metabisulphite. Tablets were prepared by direct compression according to 22 factorial design considering the factors; filler and disintegrant types. All blends contained sodium metabisulphite as antioxidant and potassium dihydrogen phosphate as microenvironmental pH adjuster. Two-way ANOVA was performed to assess effects and interactions of formulation factors on tablets characteristics. Two selected formulae (F b and F ab) were subjected to storage at 50 ºC/75 % R.H for 12 weeks, where no significant changes was observed for F ab, while marked discoloration was observed for F b. The results suggested that F ab could be a promising drug formulation with rapid disintegration and enhanced stability.
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