Design and evaluation of a novel floating osmotic pump system.

PURPOSE Find a novel delivery system for oral administration of drugs that have absorption window in the upper part of gastrointestinal (GI) track. METHODS Dipyridamole was chosen as the model drug. A novel system, which combined the osmotic pump controlled release system and the floating system, was designed; matrix tablets (MT) were prepared for compares. The effects of pH, temperature and hydrodynamic conditions on drug release and the floating behavior of floating osmotic pump system (FOP) were investigated. In vivo evaluation was performed by a three-crossover study in six Beagle dogs relative to the conventional tablet (CT). Cumulative percent input in vivo was compared with that of in vitro release profiles. RESULTS Floating behavior of FOP, drug releases from FOP and MT were sensitive to pH of dissolution media but not sensitive to temperature; the release of dipyridamole from MT was influenced by stirring rate while drug release from FOP was not. AUC of FOP was larger than MT and CT. The linear correlations between fraction absorbed in vivo and fraction dissolved in vitro was established for FOP-a true zero-order release formula, whereas only a nonlinear correlation was obtained for MT. CONCLUSIONS FOP could be a novel way for the oral administration for drugs like dipyridamole.