Development of nimesulide-loaded pH-triggered ocular in situ gels: in vitro characterization, MTT assay, and Drazie test

Objective: The present study created nimesulide-loaded in situ gels and assessed their potential application in ocular inflammation. Methods: Because in situ gels have a low viscosity, sodium alginate, and hydroxypropyl methylcellulose combined to create a nimesulide CD complex that is easy to apply. However, due to the gelation creation with pH, washing and removing it from the ocular surface becomes challenging. Production was carried out using different ratios of sodium alginate, hydroxypropyl methylcellulose, and hyaluronic acid. Results: Characterization studies led to the determination of the optimized formulation. The optimized formulation viscosity pH 5.5 = 547.3 ± 76cP, viscosity pH 7.4 = 8798.3 ± 254 cP, and pH = 5.4 ± 0.01 were obtained. In in vitro release experiments, approximately 53% of nimesulide was released by burst action within 2 h, followed by a controlled release over 12 h. Mathematical modeling of the formulations’ release kinetics revealed that they were consistent with the Korsemeyer-Peppas and Weibull models. It was determined that nimesulide-loaded in situ gels showed over 80% viability in the L929 cell line. Rats underwent no adverse conditions in Draize’s in vivo experiment. Conclusion: For this reason, the TB5 formulation may be a good choice when treating ocular inflammation. These findings may be supported by future efficacy studies using this formulation. © 2026 Informa UK Limited, trading as Taylor & Francis Group.