Effects of porous silica as drug carier on the formulation of efferverscent nystatin vaginal tablets

Nystatin was loaded into porous silica by solvent deposition technique. The physical and loaded drug mixtures were examined by differential scanning calorimetry (DSC) and powder X-ray diffractometry. The stability of the drug at different relative humidities at 25 o C in these systems was evaluated by measuring the antimycotic effectiveness. The in vitro dissolution of the drug from loaded mixtures was studied. The loaded mixtures were formulated into effervescent vaginal tablets. Physical characteristics and dissolution behavior of the prepared effervescent vaginal tablets were evaluated. DSC and powder X-ray diffraction results revealed that the drug was changed from crystalline to amorphous state depending on drug-to-carrier ratio. The drug was stable and retained its activity in loaded mixtures stored at 0% relative humidity for 2 months at 25 o C. Transformation of the drug to the amorphous state in the loaded mixtures lead to enhancement of drug dissolution. The prepared effervescent vaginal tablets complied with the standard requirements of uniformity of weight, drug content, disintegration time, dissolution, hardness and friability tests