The present investigation aims to improve the antimicrobial influence of certain antibacterial drugs, namely, neomycin (NEO), exploiting the benefits of natural oils such as tea tree oil (TTO). Therefore, a distinctive nanolipid formulation, namely, a nanoemulsion (NE), was developed using a Central Composite Factorial Design (CCD) approach depending on the amount of TTO and tween 80 as surfactant. The optimized NEO-NE formula exhibiting minimum globular size and maximum in vitro release was selected. For efficient topical delivery, NEO-NE was incorporated into a pre-formulated hydrogel. The developed NEO-NE-hydrogel was characterized by its physical characteristics such as pH, viscosity, and spreadability. Next, it was tested for stability under different conditions for 3 months. Ultimately, an irritation test was conducted followed by an antibacterial examination. The preparation demonstrated acceptable properties to be successfully applied topically. It showed non-significant changes in stability in both conditions up to 3 months storage when compared to a fresh preparation. It exhibited no irritation when applied on hairless animal skin. Finally, TTO revealed a good inhibition for the bacterial growth that could improve the influence of NEO antibacterial activity, indicating the efficiency of NE containing NEO prepared with TTO to be a promising antibacterial nanocarrier.
Keywords: antibacterial; nanoemulsion; neomycin; optimization; tea tree oil; topical delivery.