Unit system having multiplicity of means for dispensing useful agent

Claim 1

An agent dispensing device comprising: (a) a container for storing a beneficial agent, said container formed of an elastomeric polymer that is changeable from an agent storing capacity to a substantially emptied capacity over time; (b) a wall surrounding and defining an internal space that houses the container, the wall formed of a material selected from the group consisting of a semipermeable and microporous polymer that have selective fluid permeability and governs the passage of fluid into the device at a controlled rate, maintains the physical integrity of the device, and lets pressure be exerted against it, thereby assuring that pressure generated in the device is applied inwardly against the container; (c) a passageway communicating with the container and the exterior of the device for dispensing agent from the device, said passageway having internal dimensions that assist in governing the rate of release of agent from the device; (d) a lamina positioned between the wall and the container in the device, said lamina surrounding the container and formed of a material that absorbs and retains an exterior fluid admitted into the device, and is capable of changing in size at a controlled rate in response to absorbed and retained fluid; and (e) wherein, when the device is in operation, fluid is admitted into the device at a rate controlled by the wall acting in cooperation with the lamina that absorbs and retains the fluid, causing the lamina to increase in size at a controlled rate and apply pressure against the container, which urges the container to squeeze inwardly at a corresponding rate and dispense agent through the passageway to the exterior of the device at a combined rate governed by the wall, lamina, container and the internal dimensions of the passageway.