Solubility is an important physicochemical factor which affects absorption of drug and low dissolution rate in aqueous G.I.T fluid often leads to insufficient bioavailability. In the present work, an attempt was made to improve the solubility and dissolution rate of a poorly soluble drug valsartan (BCS class II) by solid dispersion method using soluplus polymer as a solubilizing agent. The formulation was prepared using drug: polymer ratios 1:1, 1:2 and 1:3 by melt extrusion method. The solubility study was carried out to find out best solubility ratio. The VAL: Soluplus ratio 1:3 shows maximum solubility in pH 1.2, pH 6.8 and pH 7.4 phosphate buffer. I.e. VAL possesses pH dependent solubility. The pure drug valsartan and prepared solid dispersion (1:3) were characterized by scanning electron microscopy (SEM), differential scanning calorimeter (DSC), fourier transform infrared spectroscopy (FT-IR), X-ray diffraction analysis (XRD), % drug content and in-vitro dissolution studies. The drug content of pure drug VAL in the polymer matrix of soluplus was obtained 53.16%. The in-vitro drug release study of solid dispersion shows improvement in drug release (i.e. 57.35%) as compared to pure drug valsartan (42.68%) within 120 min in phosphate buffer pH 6.8. The improvement in solubility and dissolution behavior of drug valsartan was due to amphiphilic structure of soluplus formed micelles in aqueous solution.
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