Device using prestretched polymer for dispensing medication

Claim 1

A drug dispensing device comprising: (a) a drug; (b) a housing made of a shape-retaining wall forming material surrounding and defining an internal space, said wall having at least one opening connecting the space with the exterior of the device, (c) a container in the housing storing the drug, the container formed of a prestretched, shrinkable polymer prepared by inducing molecular orientation by uni-axially and bi-axially stretching the polymer into an expanded high energy state, said stretched, shrinkable polymer having reserve elastic recovery to an unstretched polymer, and which container has a passageway formed in the polymer that projects through the opening for dispensing drug from the container to the exterior of the device; (d) a laminate in the housing surrounding the exterior of the container, said laminate comprising a lamina of an absorbent material and a lamina of a swellable hydrophilic polymer; and, (e) wherein, in operation when the device is present in an environment containing a biological fluid, the laminate imbibes fluid into the housing urging the laminate to swell and exert pressure on the stretched polymer thereby causing said polymer to recover to an unstretched polymer and concurrently therewith decrease in volume of the container, thereby pumping drug through the passageway from the device at a controlled rate over a prolonged period of time.