Title : Formulation and development of herbal in-situ sustained release otic gel for the treatment of otitis media using Eclipta alba
Abstract:
Otitis media remains one of the most common ear infections in young children, and conventional otic formulations often suffer from short residence time and rapid drainage from the ear canal, limiting therapeutic efficacy. This work aimed to develop and evaluate a herbal in-situ thermosensitive gel using the methanolic extract of Eclipta alba (Bhringraj), a traditionally used Ayurvedic herb with documented antibacterial, anti-inflammatory and antioxidant properties, as a sustained-release otic delivery system for otitis media. The methanolic extract was obtained by cold maceration of dried Eclipta alba powder, yielding approximately 4% w/w of a dark brownish, antimicrobially active extract. In-situ gels were formulated using poloxamer 407 as the thermosensitive polymer and poloxamer 188 as the gelling agent, with composition optimized through Design of Experiment (Design Expert software) against critical quality attributes of gelation time and gelation temperature. Three optimized batches (C1, C2 and C3) were prepared and evaluated for gelation time and temperature, clarity, pH, viscosity (pre- and post-gelation), gel strength, and in-vitro drug release using a Franz diffusion cell. All optimized batches exhibited a gelation time of 9-11 seconds and a gelation temperature of 35-37°C, closely matching physiological otic temperature, allowing the formulation to remain liquid at room temperature for easy instillation and transform into a gel in situ. The formulations showed neutral pH, satisfactory post-gelation viscosity (670-1233 cP) sufficient to prevent drainage from the ear canal, and dose-dependent antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa, with a minimum inhibitory concentration of 0.2 mg/mL. Batch C2, containing 20% w/v poloxamer 407 and 15% w/v poloxamer 188, demonstrated the most favourable in-vitro release profile, releasing nearly 70% of the drug within 5.5 hours, attributed to its comparatively lower polymer concentration facilitating faster diffusion through the gel matrix. These findings demonstrate that Eclipta alba methanolic extract can be successfully formulated into a poloxamer-based in-situ gelling system that combines the antimicrobial potential of a well-known Ayurvedic herb with the pharmaceutical advantages of sustained, localized otic drug delivery. The approach offers a promising, patient-compliant, and potentially cost-effective herbal alternative to conventional antibiotic otic drops, and opens avenues for further translational work, including synergistic herbal combinations, pre-clinical safety/efficacy evaluation, and scale-up for clinical application in the management of otitis media.
