Poloxamer Gels in Biocompatible Ionic Liquids to Treat Middle Ear Infections

The current standard of care for otitis media (OM, middle ear infection) has many limitations including contribution to bacterial antibiotic resistance and unwanted side-effects. Recent research has highlighted the potential of aqueous, drug-loaded poloxamer gels (composed of hydrophilic and hydrophobic blocks) for treating OM. These formulations can be directly administered onto the eardrum for targeted, non-invasive drug delivery. However, small-molecule chemical permeation enhancers (CPEs) must be added to the poloxamer gels to enable drug transport across the eardrum, making formulation difficult. Choline-based ionic liquids (IL) are a potential solution to this problem as they are stable, biocompatible, and can serve as both a solvent and CPE. In this work, the interactions of biocompatible poloxamers and choline-based IL are investigated to fine-tune the rheological and structural properties of the drug delivery system. Poloxamer in choline-hexenoic IL and water was shown to transition to a gel state upon heating with a corresponding gel structure of body-centered-cubic (a = 83.5 A). The anion-to-cation ratio of IL and poloxamer concentration were varied to analyze its effect on sol-to-gel transition and associated final gel structure. The results obtained from this study can be exploited to develop more effective drug delivery routes to treat OM.