FORMULATION AND EVALUATION OF SOLID SELF-MICROEMULSIFYING DRUG DELIVERY SYSTEM FOR IMPROVED ORAL DELIVERY OF OLMESARTAN MEDOXOMIL

The present work aimed at formulating a solid self micro emulsifying drug delivery system (solid-SMEDDS) for Olmesartan Medoxomil with the objective of improving the aqueous solubility, dissolution and oral delivery of the drug. Liquid SMEDDS of the drug were formulated using Capmul MCM as the oil phase, Tween 80 and Phenoxide HCO-40 as the combined surfactants after screening various vehicles. The prepared systems were characterized for various physicochemical characteristics. Ternary phase diagrams were plotted to identify the area of micro emulsification. The optimized liquid SMEDDS was transformed into a free flowing powder using Neusilin US2 as the adsorbent. The physical state of the drug in solid self micro emulsifying powder was revealed by Differential Scanning Calorimetric and X– ray powder diffraction studies which indicated the presence of the drug in the dissolved form in the lipid excipients. These findings were supported by scanning electron microscopy studies which did not show the evidence of precipitation of the drug on the surface of the carrier. Moreover the droplet size of the micro emulsion formed from self microemulsifying powder remained same as that from the liquid SMEDDS. The dissolution of the drug was enhanced significantly from the SMEDDS formulation as compared to pure drug. Similarly the drug exhibited enhanced absorption from the SMEDDS formulation through rat intestinal segment compared to its suspension. Thus it can be concluded that a lipid based drug delivery system in the solid form can be successfully developed with the potential of enhancing the solubility, dissolution and oral absorption of the drug.