Preparation and evaluation of azithromycin-loaded microspheres for oral administration

To mask the bitterness of azithromycin（AZI） and improve patient compliance, an AZI-loaded microsphere (AZI-EC MS) for oral administration was prepared by O/W emulsion solvent evaporation with ethylcellulose (EC) as carrier. The release profiles and taste-masking effect of AZI-EC MS were preliminarily assessed. Its physical properties and morphology were then investigated by differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM). The results indicated that the polymer weight of EC could influence the drug release behavior. With a drug polymer ratio of 1∶1 and mixed EC (N22/T10, 7∶3) as carrier, the cumulative release of AZI-EC MS at 0.5 h was less than 40% and reached 90% at 8 h; the drug loading efficiency of microspheres was (48.95 ± 0.86)% with smooth spherical morphology. The AZI bitterness threshold is 9.93 μg/mL with a strong bitter taste, which indicated a better taste masking effect. Therefore, AZI-EC MS prepared in this study can mask AZI bitterness and improve patient compliance, setting the stage for the research of new AZI preparations.