The aim of the present investigation was to investigate the influence of sulfobutyl ether beta-cyclodextrin (SBE-β-CD; Captisol®) on the dissolution characteristics of poorly water soluble drug diacerein (DAC). Phase solubility studies were conducted in distilled water according to Higuchi and Connors using DAC and different concentrations of SBE-β-CD. The Effect of pH on stability constant (Ks) was investigated. The kneaded binary products of DAC and SBE-β-CD were prepared using different solvents and different ratios of DAC and SBE-β-CD. The formulations were evaluated for drug content, in-vitro dissolution and by attenuated total reflectance (ATR) spectroscopy. Similarity factor (f2) was calculated for comparison of dissolution of DAC from different binary products. Phase solubility studies indicated linear increase in the DAC solubility with increase in SBE-β-CD concentration. Use of 0.1 M HCl (decreased pH) increased the complexation DAC with SBE-β-CD (1.5 fold increase in stability constant) but decreased the solubility (12 fold decrease). In-vitro release studies revealed that dissolution characteristic of DAC was improved by forming its binary products with SBE-β-CD. ATR studies indicated absence of major interactions between DAC and SBE-β-CD in kneaded products. SBE-β-CD provided an effective method to overcome the dissolution challenge for DAC but it does not show significant complexation with DAC by kneading method. pH of the solvent used significantly affect the solubility of DAC and its inclusion in the cavity of SBE-β-CD.
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