Background: Usnic Acid has been progressively reported in the literature as one of the chiefly
significant lichen metabolites exemplified by an ample diversity of applications such as antimicrobial, antifungal,
antiviral, antiprotozoal agents, etc. Herein, we shed a light on nosocomial infections and formulated
topical microspheres loaded with Usnic acid for improved antimicrobial activity. Recent patents and
novel researches were referred to pursue the present work.
Methods: Usnic acid embedded Eudragit microspheres were designed applying solvent evaporation method,
investigated for topography and drug-polymer compatibility studies. Dialysis bag method was utilized
for studying drug release kinetics. In vitro antibacterial assay was carried out against the virulent bacterial
strain of Staphylococcus aureus using the disc diffusion method.
Results: Topography studies revealed the formation of regular, micro-sized, smooth surface microspheres.
Well defined and specific structural peaks were obtained from FTIR and TGA studies, revealing drugpolymer
compatibility. The dissolution profile suggested Korsmeyer Peppas kinetic and Fickian kind of
diffusion from microspheres. The pre-eminent activity of formulated microspheres was visualized from the
disc diffusion study against Staphylococcus aureus.
Conclusion: The strong biological activity of Usnic acid –loaded Eudragit RS and Eudragit RL microspheres
provides a promising application for corresponding material as a bactericidal agent for the
alleviation of nosocomial infection. Findings paid attention to the potential of usnic acid microspheres for
effective treatment of dermal and nosocomial infections caused by S. aureus.