In Situ Gel : An Innovative Approach for Safe and Sustained Nasal Drug Delivery

The human nose has the potential to be an alternative route for the systemic delivery of a wide range of therapeutic agents. The richly supplied vascular nature of the nasal mucosa and its high drug permeation makes it a potential route for the administration of many drugs including proteins, peptides and vaccines. Nasal route is most suitable for those drugs which cannot be administered orally due to gastric degradation or hepatic first pass metabolism. In situ forming polymeric systems are formulations that are in sol form before administration into the body but once administered, undergo gelation in situ, to form a gel. The formation of in situ gel depends on factors like temperature, modulation, pH change, presence of ions etc. Temperature modulated gel is the widely accepted in situ formulation. The article provides a detailed review on the mechanism of in situ gel formation and the type of polymers used along with their evaluation. The uses of the strategies which enhance the nasal bioavailability are being used to formulate a number of drugs for delivery via the nasal route. A combination of mucoadhesive polymer along with thermoreversible polymer can be utilized for easy and safe delivery of therapeutic agents including biopharmaceuticals.