The present invention is directed to a fluid-imbibing drug delivery device having a first, low density such that it floats in the stomach contents for a predetermined prolonged period of time, during which prolonged period of time it dispenses a drug or other active agent to the stomach, and having a...http://www.google.es/patents/US5198229?utm_source=gb-gplus-sharePatente US5198229 - Self-retaining gastrointestinal delivery device
