Solubilization of Azithromycin in Microemulsions Based on Mixed Nonionic Surfactants and Mixed Oils

Water/propylene glycol/sucrose laurate/ethoxylated mono-di-glyceride/isopropylmyristate/ peppermint oil U-type microemulsions were used to solubilize azithromycin. Microemulsions dilution and interfacial factors contributing to the azithromycin solubilization were evaluated. Azithromycin solubilization capacity decreases with the increase in the aqueous phase volume fraction. Electrical conductivity of drug loaded and drug free microemulsions reveal the structural transition occurring in the microemulsion region. It was found that below 0.2 aqueous phase volume fraction the water in-oil microemulsions are present. For aqueous phase volume fraction between 0.3 and 0.7 bicontinuous microemulsions are present. For aqueous phase volume fractions above 0.8 oil-in-water microemulsions are present. The hydrodynamic radius measured by dynamic light scattering of the oil-in-water drug loaded microemulsion decrease with temperature.