Abstract
The environmental factors like change in pH, ionic concentration, temperature, osmolarity or irradiations etc physical state of formulation can change from free flowing solution to viscous gel form. This kind of phase transition from ‘sol to gel’ because of above mentioned reasons is called as in situ gelling. In situ gel is very much useful technique for improving the bioavailability of such formulations which are easily washed away from their site of administration, eg. Eye drops (in solution form) or Nasal drops. As compared to other drug delivery systems like Parenteral, Nasal, Rectal and Vaginal etc use of in-situ gel in Ophthalmic drug delivery is extensive. The intention of this new paper is to enlight the all possible areas where in-situ gel technique can be used to improve bioavailability including ophthalmic drug delivery. Therefore we have discussed here the applications of in-situ gel technique in Nasal, Oral, Rectal and Vaginal drug delivery. The most important thing required in in-situ gel is availability of suitable and compatible biodegradable polymer. Hence we have given the list of polymers (biodegradable and non-biodegradable) that may be helpful for investigators.