Development of floating in situ gelling system as an efficient anti-ulcer formulation: in vitro and in vivo studies

The aim of the present work was to design gellan gum and calcium carbonate based floating in situ gel as an efficient anti-ulcer formulation using andrographolide (AG) as a model drug. A 3(2) factorial design was used to study the effect of gellan gum and calcium carbonate on characteristic of in situ gelling system. The formulations were evaluated in terms of in vitro, in vivo anti-ulcer and histopathological study in Wistar rats. Drug content and viscosity were found in the range of 74.3 +/- 1.2-95.5 +/- 1.8% and 67.7 +/- 1.6 to 152.13 +/- 1.1 cps, respectively. Formulation gelled within 2 s and floated more than 24 h in simulated gastric fluid; an initial burst release of 11.7 +/- 0.9 to 32.4 +/- 2.1% till 1 h followed by a sustained release was observed. In vivo, the AG floating in situ gel (AGFIG) demonstrated lower acid and protein level, high hemoglobin level and negligible ulcer index. Moreover, it preserved integrity and histological aspects of the gastric mucosa as compared to pure AG and ranitidine. Improved anti-ulcer activity of AGFIG was attributed to longer residence time of AG in the stomach which improved the activity of myeloperoxidase, lipid peroxide, mucin content and glutathione peroxidase on gastric mucosal surface leading to protection from alcohol induced erosion. The study concluded that such floating in situ gelling system can be translated for existing and established anti-ulcer drugs.