Dissolution enhancement of valsartan using natural polymers by solid dispersion technique

Solid dispersions have been widely used to enhance the solubility of poorly water soluble drugs. In this study, solid dispersions of valsartan (VAL) with natural polymers such as hupu gum (HG), guar gum (GG) and xanthan gum (XG) were prepared by kneading technique in the weight ratios of 1:1,1:2,1:3 and1:4.The prepared solid dispersions were investigated by X-ray diffraction, infrared spectroscopy, differential scanning caloriemetry and solubility studies. X-ray diffraction and differential scanning caloriemetry have shown that natural polymers inhibit the crystallinity of valsartan. The infrared spectroscopy suggests that there was no chemical interaction between valsartan and natural polymers. Phase solubility studies showed that the drug solubility was increased as the concentration of polymer content was increased. The prepared solid dispersions were analysed for percentage practical yield, drug content and dissolution studies. The results demonstrated that the dissolution of GG/VAL solid dispersions was enhanced greatly at ratios of over 4/1 when compared with that of remaining ratios of GG which shows 97.90% of drug release within 60 minutes.The drug release from the solid dispersions was found to follow the first-order kinetics, Fitment into Hixson Crowell’s cube root model equation suggest the drug release mechanism could be erosion.