Study of anti-microbial effects of azithromycin nanosuspensions in comparison with drug solution

Abstract

Objectives: Azithromycin is a new macrolide antibiotic with better activity against gram negative bacteria compared to Erythromycin. The purpose of this research was to prepare azithromycin nanosuspension using Poly (lactic-co-glycolic acid) or Eudragit RS 100 polymer and compare the effectiveness of nanosuspensions with drug solutions. Methods: Azithromycin nanosuspension was prepared by Modified Quasi Emulsion Solvent Diffusion (MQESD) method. Drug and polymer were dissolved in a water miscible solvent such as aceton. The resulting solution was added to aqueous phase containing two percent of PVA 95000, under homogenization. Nanosuspensions were obtained by migration of solvent from inner to aqueous phase. The microbial culture method was used to compare the effectiveness of nanosuspensions with drug solution. Staphylococcus aureus ATCC 6538 was used in this study. The inhibition zone diameter of azithromycin was determined by diffusion method in agar medium. The obtained inhibition zone diameters for nanosuspensions were compared to those of azithromycin solution. Results: The values pertaining toinhibition zone diameters of nanosuspensions in comparison with those of drug solution were significantly higher, that indicating improved antibacterial activity of the developed formulations (P<0.01). The increased potency of formulated nanosuspensions is perhaps related to some physicochemical properties of nanosuspensions like modified surface characteristics, increased drug adsorption and uptake as well as lower drug degradation. Conclusion: Our results indicate that the potency of nanosuspensions is much more than that of drug solution in the same concentration.