Lipid-based formulations of microemulsion-loaded oleogels for the oral delivery of carvedilol

This work aimed to develop controlled-release lipid-based formulations of microemulsion-loaded oleogels for the oral delivery of the poorly soluble drug carvedilol (CARV). The microemulsion-loaded oleogels were prepared by the oleogelator Compritol (R) 888 (CP888). CARV was loaded into submicron-sized emulsions (CARV-MEs) of various ratios of surfactant and cosurfactant. The CARV-MEs were entrapped into CP888-based oleogels, forming CARV-ME oleogels. The rheological properties and dissolution studies of the CARV-ME oleogels were determined. MTT assay test was performed to ensure the safety of oleogel formulations. The optimized formulation of CARV-ME oleogel was subjected to stability studies. The results revealed that CARV-MEs were thermodynamically stable of spherical globules of average size 13.3-57.4 nm, polydispersity index (PDI) range of 0.24-0.52, and interfacial tension of 29.9 +/- 0.2 mN/m. Oleogels exhibited viscoelastic properties with more elastic behavior. The drug release rate was found to be dependent on the surfactant/cosurfactant ratio. A negative correlation was found between surfactant concentration and IC50. The optimized CARV-MEs oleogel was stable for 3 months at various storage conditions. In conclusion, the entrapment of the CARV-MEs, with various surfactant to cosurfactant ratios, into oleogels influences the dissolution rate and mechanism of drug release and the safety of CARV-MEs oleogels.