Preparation and Characterization of Azithromycin Loaded Solid Dispersion: A New Approach to Enhance in vitro Antibacterial Activity

Aim: Azithromycin (AZ) possess high permeability but low solubility in gastrointestinal (GI) fluid and exhibited unpredictable dissolution profile resulting in poor oral bioavailability. Therefore, the study was aimed to enhance the dissolution rate of AZ and evaluation of its in-vitro antibacterial activity. Materials and Methods: Solid dispersions of AZ (ASDs) were prepared by solvent evaporation technique using Na-CMC alone or in combination with Carplex-80 as carrier in different ratios. Subsequently, in-vitro dissolution study were performed followed by physicochemical characterization using differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) and finally antibacterial activity were assessed. Results: The formulation ASD-6 exhibited faster (6.59% at 5 min) and higher (20.02% at 120 min) drug release which were 4.84 and 7.94 fold higher than that of pure AZ. A significant increase in relative zone of inhibition (RZOI) was observed with ASD6 (p<0.001) when compared to that of pure AZ against S. aureus and E. coli at each sampling point. Conclusion: The in-vitro dissolution study indicated that among the six formulations AZ: Carplex-80: Na-CMC (1:3:2) complexes prepared by solvent evaporation technique exhibited highest dissolution rate and which might be responsible for enhanced antibacterial efficiency.