Enhancing the Efficacy of Azithromycin Against Bacterial Strains Using Simple Microemulsion Technique

Azithromycin is effective in the treatment of many bacterial infections, but is poorly aqueous soluble with relatively low bioavailability. The main objective of our study is to design a thermodynamically stable microemulsion formulation of azithromycin to improvise its solubility, stability, oral bioavailability and to enhance its anti-bacterial efficacy. A typical wt/wt% composition of the microemulsion formulation of azithromycin: clove oil (5%), tween 20 (30%) and water (65%) respectively was prepared by gentle mixing without the use of high energy inputs. Antimicrobial activity was performed in three different bacterial strains namely Staphylococcus aureus (ATCC 29213), Escherichia coli (ATCC 25922) and Salmonella typhi (MTCC 8767). The nanosized formulation of azithromycin with a droplet size of 8–20 nm range results in superior anti-bacterial activity when compared to the conventional formulation. Significant alteration in the membrane integrity of the interacted bacterial samples of bulk drug suspension in comparison with drug-loaded microemulsion formulation was obtained (at S. aureus-8 μg/ml, E. coli-32 μg/ml, S. typhi-32 μg/ml) by quantifying the release of UV absorbing materials. The bacterial staining with acridine orange/ethidium bromide dyes as examined through fluorescence microscopy also substantiated with the results of membrane permeability of bacteria. Thus, the investigated microemulsion system will act as the potential oral drug delivery system with beneficial efficacy in patients.