A dispenser is disclosed for delivering a beneficial agent to an environment of use. The dispenser comprises a semipermeable wall surrounding a compartment containing a heat responsive composition, and an expandable composition. A passageway in the wall connects the compartment with the exterior of the...http://www.google.com/patents/US4814180?utm_source=gb-gplus-sharePatent US4814180 - Agent dispenser comprising a semipermeable wall surrounding single-piece or two-piece container
