Enhancement of dissolution rate of Olmesartan medoxomil using urea as carrier by different solid dispersion techniques

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. As per Biopharmaceutical Classification System (BCS), Olmesartan belongs to the class-II category having poor solubility and high permeability. Since only dissolved drug can pass the gastrointestinal membrane, the proper solubility of the drug is ultimately desired. Its oral bioavailability is 26%. Hence, an attempt was made to enhance its solubility by formulating solid dispersions using different techniques viz., Melting, Kneading, Co-precipitation, Solvent evaporation and Physical mixing etc., Drug and carrier (Urea) in different ratios like 1: 1, 1: 2, 1: 3 and 1:4 were used for formulating solid dispersions. The compatibility of the drug with the carrier was checked by FTIR studies, these results revealed that there was no interaction between them. The angle of repose, bulk density, tapped density; Carr’s index and Hausner ratio were calculated for the micrometric characterization of all the solid dispersions. The drug content was found to be high and uniform in all formulations. The prepared Solid dispersion SEM4 (1:4) showed minimal wetting time of 13 seconds compared with the other formulations. In vitro dissolution, release studies in Phosphate buffer pH of 6.8 revealed that the prepared solid dispersions showed faster drug release compared with the pure drug.  The in vitro dissolution profile showed ascendency on increasing the carrier concentration