Development And Characterization Of A Tretinoin-Loaded Thermosensitive In Situ Gel For Sustained Topical Drug Delivery In Psoriasis

Background: Psoriasis is a chronic inflammatory skin disorder requiring effective topical drug delivery. Thermosensitive in situ gels may improve drug residence and provide sustained release compared with conventional topical preparations. Aim/Objectives: The study aimed to develop and characterize a tretinoinloaded thermosensitive in situ gel using Poloxamer 407 and Poloxamer 188 and to evaluate its physicochemical properties, drug incorporation, release behaviour, anti-inflammatory activity, and short-term stability. Materials and Methods: Eight formulations (F1–F8) were prepared by the cold method using different concentrations and ratios of Poloxamer 407 and Poloxamer 188. The formulations were evaluated for pH, gelation temperature, gelation time, drug content, entrapment efficiency, in-vitro drug release, anti-inflammatory activity, and stability. Results: The formulations showed pH values of 6.68–7.19, gelation temperatures of 34–47°C, drug content of 90.68–98.52%, and entrapment efficiency of 95.2–99.2%. F3 showed 35.0 ± 1.0°C gelation temperature, 38 ± 0.8 s gelation time, 98.52 ± 0.42% drug content, 98.0 ± 0.5% entrapment efficiency, and 94.8% drug release at 24 h. Its IC50 was 132.8 µg/mL. Conclusion: F3 demonstrated favourable physicochemical characteristics, sustained drug release, in-vitro anti-inflammatory activity, and satisfactory short-term stability, supporting further investigation as a topical tretinoin delivery system.