ABSTRACT:
Recently, controlled and sustained drug delivery has become the standard in modern pharmaceutical design and an intensive research have been undertaken in achieving much better drug product effectiveness, reliability and safety. Conventional oral dosage forms pose low bioavailability problems due to their rapid gastric transition from stomach, especially in case of drugs which are less soluble at alkaline pH of intestine. Similarly, drugs which produce their local action in stomach get rapidly emptied and do not get enough residence time in stomach. So, frequency of dose administration in such cases is increased. To avoid this problem, various efforts have been made to prolong the retention time of drug delivery system. Among oral dosage form, liquid dosage forms are more prone to low bioavailability because of their quick transit from the stomach/duodenum. To produce sustained release formulation of an oral liquid formulation could be successfully augmented substantially through a strategy of liquid in situ gelling system. The formation of gels depends on factors like temperature modulation, pH change, presence of ions and ultra violet irradiation, from which the drug gets released in a sustained and controlled manner. Various biodegradable polymers that are used for the formulation of in situ gels include gellan gum, alginic acid, xyloglucan, xanthan gum, pectin, chitosan, poly(DL-lactic acid), poly(DL-lactide-co-glycolide). The in situ gel forming polymeric formulations offer several advantages such as sustained and prolonged action in comparison to conventional drug delivery systems and increase bioavailability of drug as well as produce patient compliance by ease of administration and reducing dosing frequency. From a manufacturing point of view, the production of such devices is less complex and thus lowers the investment and manufacturing cost.