Floating in situ gelling system of Amoxicillin with increased gastric residence time can be formulated using Xanthan gum and Guar gum as a natural polymer. This floating in situ gel is based on the pH triggered and ion exchange. The optimized formulation F6 provided sustained in vitro release of drug over an extended period of time up to 12 hrs. The drug release from gel structure follows a zero order release. Это и многое другое вы найдете в книге Floating (Doshi Nidhiben and Mukesh S. Patel)