Development of Microemulsion of Marjoram Oil in the Line of Treatment of Otitis Media

Background: Marjoram oil, an antimicrobial agent, has significant potential for industrial applications due to the presence of a high proportion of chemical components such as terpinene-4-ol, sabinene hydrate, thymol, and carvacrol. These components are effective against various broad-spectrum bacteria. Practically, microemulsions of oily drugs improve antibacterial effects by increasing penetration into the skin and bacteria. The topical microemulsion of marjoram oil for otitis media has not yet been explored. Therefore, the present study focuses on the development of a microemulsion of marjoram oil in the context of in vitro antibacterial studies against Streptococcus pneumoniae, Moraxella catarrhalis, and Haemophilus influenzae, the microorganisms responsible for otitis media infections. Materials and Methods: Marjoram oil was extracted via hydrodistillation and evaluated for physicochemical properties. It was combined with a co-surfactant and surfactant, emulsified with water to create a microemulsion. A 1:1 ratio of surfactants to co-surfactant was used, with varying concentrations of Smix and oil. Formulations were developed using a triangular diagram and titration method, and evaluated for compatibility, droplet size, polydispersity index, and zeta potential. The stable formulation F7 was tested for antibacterial activity against chloramphenicol ear drops. Results: Formulation F7 contained the highest oil quantity (44.99% w/w), with water (35.73% w/w) and Smix (19.28% w/w). Its globule size was 370.3 nm, polydispersity index 0.48, and zeta potential -25.7 mV. FTIR studies confirmed formulation compatibility. The F7 microemulsion (200 μg/mL) showed a greater zone of inhibition compared to chloramphenicol (100 μg/mL) and was effective against Streptococcus pneumoniae, Moraxella catarrhalis, and Haemophilus influenzae. Conclusion: The developed microemulsion of marjoram oil was stable and effective against the microorganisms causing otitis media.