Formulation Of Regioselective Floating Matrix Tablets Of Dextromethorphan Using Gas Forming Technique And Evaluation

The present study deals with the formulation and evaluation of gastroretentive floating tablets of dextromethorphan. Dextromethorphan is a highly potent and commonly used antitussive agent. It has no narcotic, analgesic or addictive properties and its potency as an antitussive agent is almost equal to that of codeine. The purpose of this research is to increase the gastric residence time by preparing gastroretentive floating tablets whereby making it available at its site of absorption and to achieve an extended action for a time period of 12 hrs. Dextromethorphan floating tablets were prepared by direct compression method using various grades of METHOCEL, POLYOX and CARBOPOL with three different concentrations. Preformulation studies were carried out and the compatibility of the drug with the excipients was confirmed through differential scanning calorimetry studies. The prepared gastroretentive floating tablets were evaluated for uniformity of weight, hardness, friability, density, drug content, floating lag time, floating time, swelling index and in vitro dissolution studies. The optimized formulations F3, F5 and F11 showed a floating time more than 12hrs with matrix integrity in pH 1.2. The in vitro release studies revealed that the drug release was sustained upto 12hrs. Optimized formulations showed no significant change in physical appearance, pre and post compression parameters and drug dissolution studies after storage at 40 degrees C +/- 2 degrees C and 75% +/- 5% relative humidity in a humidity chamber for 1 month. Using Higuchi's Model and the Korsmeyer equation, the drug release mechanism from the floating sustained release tablets was found to be Anomalous (non-Fickian) diffusion.