Formulation development and in-vitro characterization of bilayer and floating-bioadhesive

The aim of the present research was to develop a bilayer and floating-bioadhesive drug delivery system exhibiting a unique combination of floatation and bioadhesion to prolong residence in the stomach using propranolol hydrochloride as a model drug. The sustained layer was compressed and granules of the floating layer were added to it then both layers were compressed using a single station rotary press. Granules and tablets were characterized using the official method. Hydroxypropyl methylcellulose (HPMC) and sodium bicarbonate were added to the floating layer and, when immersed in 0.1 mol/ l HCl, the tablet expands and rises to the surface where the drug is gradually released without interference from gas bubbles. The in vitro drug release, buoyancy lag-time, detachment force and swelling index were evaluated. The in vitro drug release from the tablet was controlled by the amount of HPMC in the sustained release layer. The floating ability of the tablets was studied. The release of propranolol hydrochloride from the tablets followed the matrix first order release model. The concentration of HPMC significantly affects the drug release rate, buoyancy lag-time, detachment force and swelling characteristics of the tablets. The tablet was buoyant for upto 8 h. This kind of tablet exhibits independent regulation of buoyancy and drug release.