Formulation and evaluation of ophthalmic In-situ gel using moxifloxacin coated silver nanoparticles

Objective: In situ gels are systems which are applied as solutions or suspensions and are capable of undergoing rapid sol-to-gel transformation by external stimulus. In situ gels overcome the shortcoming of eye drops like poor bioavailability and poor therapeutic response due to rapid dilution on instillation and wash out. Nano particles have shown improved performance of drug delivery system like increased bioavailability, drug targeting, increased stability, prolonged action and most important reduced dosing frequency. The objective of the present study was to synthesize moxifloxacin capped silver nanoparticles having enhanced antimicrobial action and then formulate it into in situ ophthalmic gelling system which will prolong its residence time for better bioavailability. Methods: Moxifloxacin belongs to class of antibiotics called fluoroquinolones which is popularly used as a broad spectrum antibiotic in the treatment of ophthalmic infections like Conjunctivitis, Blepharitis, Keratitis, Endophthalmitis. Silver is a well-known antimicrobial agent. The in situ gel was formulated using Poloxamer 407 which is temperature induced gelling agent and HPMC K4M which is known to increases mucosal adhesivity and enhance viscosity in order to achieve the desired consistency so as to facilitate sustained drug release. The developed formulations were evaluated for clarity, pH measurement, gelling capacity, drug content, isotonicity, microbiological studies, rheological studies and in vitro drug release. Results: Experimental data demonstrated that the nanoparticles were successfully synthesized and in situ gel was successfully formulated with good parameters in terms of clarity, pH measurement, gelling capacity, drug content and isotonicity. In situ gel formulation (F5) showed in vitro sustained release profile with polymer composites Poloxamer 407 and HPMC K4M. In Vivo Bio-distribution studies of Tc99 labeled Ag-Mox NPs by Micro SPECT/CT showed there was significant increase in ocular residence time of in situ gel as compared to Tc99 labeled marketed ophthalmic solution marketed formulation. Conclusion: The developed system can be a promising alternative to the conventional eye drops due to its ability to enhance availability through its prolonged drug release and longer precorneal residence time. In addition, the ease of administration and the expected reduced frequency of administration will result in better patient compliance.