Mucoadhesive insitu nasal gel- A novel approach

Insitu gel is a novel dosage form for nasal delivery of various drugs. It is instilled into the nasal cavity as low viscosity solution and then forms gel after coming in contact with the nasal mucosa. It also prolongs the contact time between drug and absorptive sites in the nasal cavity. Insitu nasal gel has got importance due to various advantages like rapid drug absorption, rapid onset of action, to avoid first pass metabolism and the drugs which are not suitable by other routes are given by nasal route. This review article contains various factors that influence nasal drug absorption like molecular weight, chemical form, polymorphism, solubility, dissolution rate, lipophilicity, pH, viscosity and osmolarity. Further, this review gives incite for the preparation of insitu nasal gel by various methods viz., suspension polymerization, polymerization by irradiation, chemically and physically cross linked hydrogels etc. Evaluation of gels for gelation temperature, gelation time, appearance, pH, drug content, invitro permeation studies, mucoadhesive strength, viscosity and rheological studies are also discussed. The review also gives hands on information of recent patents applied/granted for this novel drug delivery system.