• Whitley Wichmann posted an update 2 years, 9 months ago

    In situ gel forming drug delivery is a type of mucoadhesive drug delivery system.The formation of gel 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.Mainly in situ gels are administered by oral, ocular, rectal, vaginal, injectable and intraperitoneal routes.In situ gelling system becomes very popular nowadays because of their several advantages over conventional drug delivery systems like sustained and prolonged release of drug, reduced frequency of administration, improved patient compliance and comfort.These hydrogels are liquid at room temperature but undergo gelation when in contact with body fluids or change in pH.These have a characteristic property of temperature dependent, pH dependent and cation induced gelation.Compared to conventional controlled release formulations, in situ forming drug delivery systems possess potential advantages like simple manufacturing process, ease of administration, reduced frequency of administration, improved patient compliance and comfort.In situ gel forming drug delivery is a type of mucoadhesive drug delivery system.In contrast to very strong gels, they can be easily applied in liquid form to the site of drug absorption.At the site of drug absorption they swell to form a strong gel that is capable of prolonging the residence time of the active substance.Both natural and synthetic polymers can be used for the production of in situ gels.After emptying of the Targetmol’s Allantoin stomach contents, the dissolve drug available for absorption in the small intestine.Aspirin and nonsteroidal antiinflammatory drugs are known to cause gastric lesions, and slow release of such drugs in the stomach is unwanted.Thus, drugs that may irritate the stomach lining or are unstable in its acidic environment should not be formulated in gastroretentive systems.So, frequency of dose administration in such cases is increased.Several gastro retentive drug delivery approaches being designed and developed.FDDS are low density systems that have sufficient buoyancy to float over the gastric contents and remain in the stomach for a prolonged period.Gas can be introduced into the floating chamber by the volatilization of an organic solvent or by the carbon dioxide produced as a result of an effervescent reaction between organic acids and carbonatebicarbonate salts.The matrices are fabricated so that upon arrival in the stomach, carbon dioxide is liberated by the acidity of the gastric contents and is entrapped in the gellified hydrocolloid.This produces an upward motion of the dosage form and maintains its buoyancy.Recently a multipleunit type of floating pill, which generates carbon dioxide gas, has been developed.In one approach, intimate mixing of drug with a gel forming hydrocolloid which results in contact with gastric fluid after oral administration and maintain a relative integrity of shape and a bulk density less than unity within the gastric environment.The air trapped by the swollen polymer confers buoyancy to these dosage forms.Excipients used most commonly in these systems include hydroxyl propyl methyl cellulose polyacrylates, polyvinyl acetate, carbopol, sodium alginate, calcium chloride, polyethylene oxide and polycarbonates B.This forms raft layer on top of gastric fluid which releases drug slowly in stomach.Such formulation typically contains antacids such as aluminium hydroxide or calcium carbonate to reduce gastric acidity.