Abstract
Stimuli sensitive hydrogels are hydrophilic, three dimensional networks, which are able to imbibe large amount of water or biological fluids and undergoes a phase transition after receiving a specific stimulus.
Ophthalmic drug delivery is often impaired by removal mechanism (blinking, tears) and by the barriers of the pre corneal areas and further patients do not seek medical attention until the disorder is well established because of lack of symptoms. Conventional topical treatments have measure drawbacks including poor ocular bioavailability i.e. less than 5 % of administered active drug is absorbed or becomes available at the site of physiological activity. The reduced therapeutic responses and the poor bioavailability exhibited by the conventional dosage forms are due to rapid pre corneal elimination of the drug, tear turnover, lacrimal drainage and degradation by enzymes. Low absorption results in short duration of action and high frequency of eye drop instillation is associated with discomfort of patients. This problem was solved by using stimuli sensitive hydrogels that are instilled as drops in eye and undergo a phase transition in cul-de-sac. These hydrogels are able to prolong the residence time of drug in pre corneal cavity due to enhanced viscosity by stimulation of pH. The developed hydrogels was therapeutically effacious, stable, non-irritant and In-vitro drug release for 8 hours was observed.