Effect of Surfactant on Azithromycin Dihydrate Loaded Stearic Acid Solid Lipid Nanoparticles

Azithromycin dihydrate is a macrolide antibiotic used for the treatment of several types of bacterial infections. The drug shows low oral bioavailability due to its low solubility. In the present work solid lipid nanoparticles of azithromycin dihydrate were formulated, keeping in view enhancement of the solubility and rate of dissolution of the drug.

Azithromycin dihydrate loaded stearic acid nanoparticles were formulated by high shear homogenization using three different surfactants, namely Tween 20, poloxamer 188, and poloxamer 407, at a varied lipid surfactant ratio while keeping the quantities of the active ingredient constant. Twelve such formulations were prepared. The nanoparticles obtained were evaluated for drug content, % drug loading, % entrapment efficiency, particle size analysis, zeta potential, surface morphology, Fourier transmission infrared spectroscopy, in vitro drug release, and stability.

All the formulations showed good entrapment efficiency and high percentage of in vitro release with a particle size suitable for lymphatic absorption. The nanoparticles formulated with poloxamer 188 showed better characteristics compared to the other surfactants.

This study indicates that stearic acid nanoparticles of azithromycin dihydrate prepared by high shear homogenization can be successively used for improvement of dissolution and thereby oral bioavailability of the drug.