Abstract            Volume:14  Issue-7  Year-2026         Original Research Articles

Online ISSN : 2347 - 3215 Issues : 12 per year Publisher : Excellent Publishers Email : editorijcret@gmail.com

Conventional liquid and semisolid dosage forms applied to mucosal or periocular surfaces are frequently limited by short residence time, rapid clearance, and poor site specificity, which together reduce bioavailability. In situ gel systems address these limitations by remaining as free-flowing, easily administered solutions that undergo a sol-to-gel phase transition on contact with the physiological environment, triggered by temperature, pH, ionic strength, or specific chemical interactions. Once gelled, the resulting matrix forms a depot at the site of application that prolongs drug residence and supports sustained, controlled release. This property makes the approach particularly valuable for ophthalmic, nasal, oral, vaginal, rectal, and parenteral formulations, where it improves patient compliance by reducing dosing frequency compared with conventional drops, solutions, or injections. This review summarises the principal sol-gel transition mechanisms (thermosensitive, pH-sensitive, ion-activated, and enzyme/redox-responsive systems), the natural and synthetic polymers used to engineer them, and the Quality by Design and Design of Experiments approaches increasingly applied to optimise gelation behaviour and drug release. It further examines regulatory expectations, safety and biocompatibility requirements, manufacturing and scale-up challenges, and the comparative performance of in situ gels against tablets, ointments, and injections. Representative marketed products and preclinical/clinical evidence are discussed by administration route, and emerging directions in nanotechnology-enabled, personalised, and artificial-intelligence-assisted formulation design are outlined. Overall, the availability of a biocompatible, appropriately triggered polymer system remains the central determinant of successful in situ gel development.

Download this article as