Evaluation of formulation variables on azithromycin nanoparticles prepared by emulsification solvent diffusion method using quality by design approach

The study aims to investigate the effect of formulation variables on the characteristics of azithromycin (AZI) nanoparticles using a quality by design approach. AZI nanoparticles were prepared by the emulsification solvent diffusion method. Two critical factors, the ratio of AZI: Eudragit EPO (X 1 ) and volume of outer aqueous medium (X 2 ), were chosen as independent variables for central composite design. The optimized formulation was further characterized by Fourier transform infrared spectroscopy, X-ray diffractometry, transmission electron microscopy, and dissolution test. The obtained results showed variability of mean particle size, entrapment efficacy, and zeta potential from 200 to 1232 nm, 10.78 to 75.9%, and 31 to 43 mV, respectively. The main coefficients indicated that the ratio of AZI: polymer (X 1 ) possessed a synergistic effect on mean particle size (Y 1 ), and volume of outer aqueous medium (X 2 ) had an antagonistic effect on particle size. The interaction between the ratio of AZI: Eudragit EPO (X 1 ) and volume of outer aqueous medium (X 2 ) exhibited a significant antagonistic effect on entrapment efficacy (Y 2 ) ( p <0.05). AZI existed in an amorphous state in nanoparticles that were spherical and homogeneous in shape. The nanoparticles revealed the Korsmeyer-Peppas release model, from which AZI was released faster compared to raw material.