Investigation of effect of drug solubility on colon specificity of polysaccharide polymers khaya gum and guar gum

The fast disintegrating core tablets of budesonide and domperidone, were prepared separately by direct compression technique. Later, these tablets were compression coated with khaya gum/guar gum, polysaccharide polymers. These tablets were further coated using eudragit S-100 by dip coating technique. The tablets were evaluated for hardness, friability, weight variation, swelling index, drug content, in vitro release studies. In vitro drug release studies were carried out in presence and absence of rat cecal contents and revealed that khaya gum/guar gum, when used as compression coating, though protected the poorly soluble drug budesonide from being released in the upper parts of the gastrointestinal tract to some extent, but could not prevent the release of a weakly basic drug domperidone significantly. Further, the enteric coated formulations completely protected the drugs irrespective their solubility from being released in the upper parts of the gastrointestinal tract, and released the drug in the colon by bacterial degradation of gums. Though, the cumulative amount of drug release from the formulations of two different drugs remained same, the release difference in the different parts of gastrointestinal tract was observed from compression coated formulations due to their difference in solubility in the upper parts of gastrointestinal tract. It was also found that different release profiles in presence and absence of rat cecal contents. Different solubility nature of the drugs did produce significant effect on the MDT values of compression coated tablets and enteric coated tablets. Further, effect of dissolution environment on MDT values was observed only with formulations containing budesonide as drug but not with domperidone, indicated that the effect of solubility of drugs plays a significant role in determining the efficiency of colon specificity of polysaccharide polymers in targeting the drugs to colon.