In vitro, ex vivo, and in vivo evaluation of polysaccharide based thermo-sensitive in situ gel for the treatment of glaucoma.

One of the disadvantages of traditional ophthalmic formulations is their short residence time in the eye. An in situ gel is recommended as a remedy, as it can be converted into a gel upon contact with the eye and adhere for an extended period. Tamarind seed polysaccharide (TSP) is non thermo-sensitive and possesses the necessary properties to be used as a vehicle for administering medication to the eye. However, the administration of medication into the eyes through TSP based in situ gel has not yet been studied. N-isopropyl acrylamide was grafted onto TSP to make it temperature sensitive. Then, a TSP-based thermo-sensitive in situ gel-forming solution loaded with dorzolamide hydrochloride (2% w/v) was developed and evaluated through in vitro, ex vivo, and in vivo tests. The in situ gel forming solution turns into a gel at 37°C. The safety and efficacy of the formulation were confirmed through an in vivo study on rabbit eyes with induced glaucoma. The findings indicate that the in situ gel significantly reduced intraocular pressure (IOP), with effects comparable to those of marketed eye drops.