Gellan gum-based in-situ gel formulations for ocular drug delivery: A practical approach

Ophthalmic disorders significantly impact global health, affecting millions worldwide. Conventional treatments often face challenges related to poor bioavailability and short residence times on the ocular surface. In recent years, in-situ gels prepared using different natural gums including gellan gum has been investigated as a viable means of improving ocular medication delivery. Gellan gum undergoes ionotropic-gelation in the presence of multivalent cations, making it suitable for ocular formulations. The synthesis and purification of gellan gum involve microbial fermentation processes. Incorporating gellan gum into ophthalmic formulations offers several advantages, including prolonged residence time, enhanced drug retention, and improved bioavailability. Characterisation techniques such as gelling capacity determination, FTIR spectroscopy, TEM, viscosity and rheological studies and ex-vivo or in-vitro release studies are crucial for assessing the structural and functional properties of gellan gum-based in-situ gels. Numerous investigations have exhibited gellan gum's potential in different drug loaded in-situ gels for ophthalmic uses, resulting in extended drug residency on the ocular surface and enhanced therapeutic effects. The current review presents a comprehensive discussion on preparation, characterisation, recent applications and future prospects of gellan gum-based in-situ gels for ocular drug delivery. In addition, it covers molecular structure, synthesis and characterisation of gellan gum.