Formulation, In-Vitro and In-Vivo characterization of Vardenafil Loaded Floating In-Situ Gel: An investigational study For Enhancement of Oral Bioavailability.

The principle purpose of this research work was to enhance oral bioavailability of vardenafil through formulation into gastroretentive in-situ gelling system using different concentrations of sodium alginate as gelling polymer, calcium carbonate as gas providing agent and source of calcium ion necessary for ionic gelation, calcium chloride as cross linking agent and sodium citrate as fluidity maintaining agent. The prepared batches were subjected to various evaluation parameters like viscosity, pH, floating lag time and floating period, gelling capacity and drug content. All prepared batches were clear solutions with pH ranges from 6.9 to 7.9. The viscosity before gelation ranges from 54 to 480 cp and after gelation from 435 to 5321 cp. All prepared batches float after few seconds and remain buoyant for more than 12 hours. They convert into gel 1-2 second or immediately after entering 0.1N Hcl pH1.2. The drug distributed homogeneously within prepared in-situ gel with drug content fall within the range of 94.6 to 100.1%. An increase in the concentration of sodium alginate, calcium carbonate and calcium chloride retard the drug release from the prepared in-situ gel. The formulation batch F4 which showed reasonable viscosity, prolonged floating period and sustained vardenafil release was selected for further in-vivo investigation. Formulation of vardenafil into in-situ gel increased tmax and decreased cmax thus enhancing its bioavailability.