Formulation and in vitro evaluation of nitrofurantoin floating matrix tablets

The aim of this study was to develop nitrofurantoin floating matrix tablets, which after oral administration will prolong the gastric residence time, control the drug delivery to the body, thus increase the drug bioavailability and diminish gastric irritating side effects. Hydroxypropyl methylcellulose (HPMC) of different viscosity grades together with a gas generating agent (sodium bicarbonate) and other optional additives were examined to optimize the floating characters of the prepared tablets. The in vitro study of the floating behavior of the prepared tablets in simulated gastric fluid (pH 1.2, enzyme free) at 37°C showed that tablets eroded upon contact with the release medium. The drug release rate, polymer swelling, and tablet erosion varied markedly with the type of matrix materials. The results also showed that tablet composition had profound effect on the floating behavior and drug release. All formulations prepared using HPMC E4M with the incorporation of sodium bicarbonate showed suitable floating lag time (20 s), with duration of floating more than 8 h. The drug release from those tablets was sustained over 8 h.