The invention is directed to a device for delivering an active agent formulation for a predetermined administration period. An impermeable reservoir is divided into a water-swellable agent chamber and an active agent formulation chamber. Fluid from the environment is imbibed through a semipermeable plug...http://www.google.com.tw/patents/US7655257?utm_source=gb-gplus-share專利 US7655257 - Sustained delivery of an active agent using an implantable system
