ABSTRACT:
The poor solubility of drug substances in water and their low dissolution rate in aqueous G.I.T fluid often leads to insufficient bioavailability. Solubility is an important physicochemical factor affecting absorption of drug and its therapeutic effectiveness. Consequences of poor aqueous solubility would lead to failure in formulation development. In the present investigation, an attempt was made to improve the solubility and dissolution rate of a poorly soluble drug, Valsartan by solid dispersion method using sodium starch glycollate (SSG) as carrier. Four different formulations (SD1 to SD4) were prepared with varying drug: carrier ratios viz.1:1, 1:3, 1:5 and 1:9 and the corresponding physical mixtures were also prepared. The formulations were characterized for solubility parameters, drug release studies and drug-polymer interactions by using phase solubility studies, dissolution studies; XRD analysis, FTIR spectrum, TLC analysis and UV overlay spectra. All the formulations showed marked improvement in the solubility behavior and improved drug release. Formulation containing drug: polymer ratio of 1:9 showed the best release with a cumulative release of 87.18% as compared to 34.91 % for the pure drug. The release increased with increase in carrier content. The interaction studies showed no interaction between the drug and the carrier. It was concluded that sodium starch glycollate as a carrier can be very well utilized to improve the solubility of poorly soluble drugs.