Development and Evaluation of Cyclosporine a Mixed Micelle Eye Drops for Enhanced Ocular Drug Delivery

Ocular drug delivery is hindered by anatomical and physiological barriers that limit drug bioavailability. Among emerging solutions, mixed micelle systems offer promising potential for enhancing the efficacy of ocular formulations. This study investigates the development and evaluation of a novel cyclosporine A (CsA) micellar eye drop formulation using octylphenol polyethylene glycol ether 40 (OP-40), a surfactant with favorable ocular delivery properties, and polyoxyethylene hydrogenated castor oil 40 (RH-40), a non-ionic surfactant that can enhance the dispersion and stability of the system. OP-40 was optimized through a purification process, and a hybrid micelle system was developed by screening excipients and refining the formulation process. The critical micelle concentration (CMC), crystalline form of CsA, interactions between surfactants and excipients, and the influence of excipients on buffer capacity were systematically examined. The resulting eye drops demonstrated favorable physicochemical characteristics, including pH, osmolality, and stability under both accelerated conditions and long-term storage at room temperature. Furthermore, the formulation exhibited no ocular irritation in rabbit models, confirming its safety. In conclusion, OP-40-based CsA mixed micelle eye drops provide a promising strategy to overcome ocular drug delivery challenges, with significant potential to enhance bioavailability and therapeutic efficacy in ophthalmic applications.