Osmotic pump with means for dissipating internal pressure by allowing osmotic material to be ejected from the container above a set internal pressure

摘要

An osmotic pump (10) for providing sustained delivery of a beneficial agent that has a mechanism for preventing excessive internal pressure is disclosed. The pump (10) comprises a reservoir (20) for holding the beneficial agent, an osmotic composition (16) comprising an osmotic agent, at least one wall defining a boundary of the reservoir (20), at least one vent (26) formed through the at least one wall, a semi-permeable membrane (22) positioned to seal the at least one vent (26). The semi-permeable membrane (22) being capable of displacement relative to the reservoir (20) when a threshold pressure in the osmotic pump (10) is reached, wherein the vent (26) is exposed to the osmotic agent (16) and at least a portion of the osmotic agent is released (16) from the reservoir when the semi-permeable membrane (22) is displaced relative to the reservoir (20). In use, when the beneficial agent has been completely expelled, the semi-permeable membrane (22) has pressure exerted upon it by the osmotic composition (16). This displaces the semi-permeable membrane (22) revealing the vent (26) to the osmotic composition (16), allowing its escape by small increments. This now prevents the semi-permeable membrane (22) from being separated from the reservoir (20) completely.