Preparation and characterization of solid dispersions of Valsartan with Poloxamer 188

Solid dispersions in water-soluble carriers have attracted considerable interest as a means of improving the dissolution rate and hence possibly bioavailability, of a range of hydrophobic drugs. The poor solubility of valsartan leads to poor dissolution and hence variation in bioavailability. The purpose of the investigation was to increase the solubility and dissolution rate of valsartan for enhancement of oral bioavailability. In this investigation solid dispersions with poloxamer 188 were prepared by melting method and evaluated for physico-chemical parameters and dissolution. The physical mixture(s) and solid dispersion(s) were characterized for flow properties, particle size, drug-carrier interaction, drug content, solubility and dissolution rate. The solubility of drug increased with increasing polymer concentration. The dissolution rate was substantially improved for valsartan from its solid dispersion compared with pure drug and physical mixtures. As indicated from X-ray diffraction pattern, DSC thermograms and SEM photographs, valsartan was in the amorphous form, which confirmed the better dissolution rate of solid dispersions. The solid dispersion was stable under accelerated storage conditions. The solid dispersion technique with poloxamer 188 as a carrier provides a promising way to enhance the solubility and dissolution rate of valsartan