The optimal drug concentration required at the site of action for the ocular treatment cannot be attained mainly due to precorneal drug loss; tear turn over, solution drainage by gravity and naso-lachrymal drainage. The purpose of present work was to overcome these problems by developing an in situ gel forming systems. Major progress has been made recently in ophthalmic drug delivery systems in the form of improved levels of patient acceptance and more specifically development of droppable gels

more »

... (in situ forming gels).The droppable gels are liquid upon instillation and they undergo a phase transition in the ocular cul de sac to form a viscoelastic gel and this provides a response to environmental changes. Parameters that can change and trigger the phase transition of droppable gels include pH, temperature and ionic strength. In addition to this combination system also reported. Three methods have been employed to cause phase transition on the surface because of change in temperature, pH and ion composition. [1]