Oil-water-poloxamer emulsions for non-invasive treatment of otitis media

The physics and mechanisms involved in solution-to-gel transitions of aqueous poloxamers with additives is one region of polymer physics that remains difficult to design and control. Tuning transition properties of such solutions remains important for transdermal and transtympanic drug delivery applications. Here, rheometry is utilized alongside differential scanning calorimetry and small-angle X-ray scattering to elucidate mechanisms behind gelation of oil-water emulsions containing Poloxamer 407, methyl laurate, lower molecular weight reverse poloxamers, and ciprofloxacin—for use in noninvasive treatment of otitis media (ear infections). This system can be tuned to gel at body temperature without a significant loss of mechanical properties, leading to greater efficacy of drug delivery systems. The hydrophobic nature of methyl laurate was found to induce gelation in poloxamer concentrations thought to be below the usable range for gelation applications. We show that such solutions allow for increased sensitivity to additives, allowing for more precise modifications. Specifically, modifications to reverse poloxamer molecular weight and poly(ethylene oxide) content are shown to significantly impact gelation properties and antibiotic drug release profiles as compared to neat Poloxamer 407-reverse poloxamer systems. These insights are promising for the continued improvement of noninvasive drug delivery systems for otitis media and other relevant transdermal treatment methods.