Claims for Patent: 6,132,420

Summary for Patent: 6,132,420

Title:	Osmotic delivery system and method for enhancing start-up and performance of osmotic delivery systems
Abstract:	The present invention relates to an osmotically driven agent delivery system for delivering a beneficial agent. The osmotic delivery system includes an osmotic agent which operates by imbibing fluid from an outside environment, causing the release of a beneficial agent. The osmotic delivery system includes a liquid or gel additive surrounding the osmotic agent for enhancing start-up and lubricating the osmotic agent. The liquid or gel additive is an incompressible lubricating fluid which fills any air gaps between the osmotic agent and the walls of a chamber and substantially reduces start-up delays.
Inventor(s):	Dionne; Keith E. (Cambridge, MA), Lautenbach; Scott D. (San Mateo, CA)
Assignee:	Alza Corporation (Mountain View, CA)
Application Number:	08/970,530
Patent Claims:	1. An osmotic drug delivery device comprising: a capsule including a first chamber containing a beneficial agent and a second chamber containing an osmotic agent, said first chamber having an opening through which the beneficial agent may be delivered from the first chamber to a location external of the first chamber; a movable separating member positioned in the capsule between the first chamber and the second chamber; a wall of the second chamber including a fluid permeable portion allowing fluid to pass from a surrounding environment into the second chamber; and an incompressible fluid additive located within the second chamber and substantially surrounding the osmotic agent. 2. The osmotic drug delivery system according to claim 1, wherein the osmotic agent is in a tabular form and the fluid additive surrounds the tabular osmotic agent. 3. The osmotic drug delivery system according to claim 1, wherein the separating member is a slidable piston. 4. The osmotic drug delivery device according to claim 1, wherein the fluid permeable portion is a membrane. 5. The osmotic drug delivery device according to claim 1, wherein the osmotic agent is a tablet. 6. The osmotic drug delivery device according to claim 1, wherein the fluid additive is a lubricating liquid for preventing freeze-up of the osmotic agent. 7. The osmotic drug delivery device according to claim 1, wherein the fluid additive is a gel. 8. The osmotic drug delivery device according to claim 1, wherein the fluid additive includes PEG. 9. The osmotic drug delivery system according to claim 1, including at least one gap between an inner surface of the capsule and the osmotic agent, said fluid additive filling the at least one gap to improve start-up time. 10. The osmotic drug delivery system according to claim 1, wherein the osmotic agent includes NaCl and the fluid additive includes PEG. 11. An osmotic drug delivery device comprising: an enclosure holding at least one osmotic agent tablet which imbibes fluid from a surrounding environment and swells to cause delivery of a beneficial agent; and an incompressible fluid filler located within the enclosure and at least partially surrounding the osmotic agent tablet. 12. The osmotic drug delivery system according to claim 11, wherein the fluid filler is an osmotic agent. 13. The osmotic drug delivery system according to claim 11, wherein the osmotic agent is a fluid swellable material causing delivery of the beneficial agent at a controlled rate. 14. The osmotic drug delivery device according to claim 11, wherein the fluid filler is a lubricating liquid. 15. The osmotic drug delivery device according to claim 11, wherein the fluid filler is a gel. 16. The osmotic drug delivery device according to claim 11, wherein the fluid filler is PEG 400. 17. The osmotic drug delivery system according to claim 11, including at least one gap between an inner surface of the enclosure and an exterior surface of the osmotic agent tablet, the fluid filler filling the at least one gap. 18. The osmotic drug delivery device according to claim 11, wherein the enclosure includes a first chamber for containing the beneficial agent and a second chamber, the second chamber containing the osmotic agent tablet and the fluid filler. 19. The osmotic drug delivery device according to claim 18, wherein the first chamber and the second chamber are separated by a partition. 20. The osmotic drug delivery system according to claim 19, wherein the partition is a slidable piston. 21. A method of improving start-up time of an osmotic drug delivery system that includes an enclosure, an osmotic agent tablet provided within the enclosure, and a gap between an inner surface of the enclosure and an outer surface of the osmotic agent tablet, comprising the step of removing gas between the outer surface of the osmotic agent tablet and the inner surface of the enclosure by providing an incompressible fluid in the gap. 22. An osmotic drug delivery device comprising: an enclosure; a partition dividing the enclosure so as to define a first chamber located on a first side of the partition and a second chamber located on a second side of the partition opposite from the first side, the first chamber holding a beneficial agent and the second chamber holding an osmotic agent, a portion of the enclosure that defines the first chamber being substantially impermeable to fluids, another portion of the enclosure that defines at least a part of the second chamber being permeable to fluids, the osmotic agent for imbibing fluid from a surrounding environment through said another portion of the enclosure and for swelling to cause delivery of the beneficial agent; and an incompressible fluid filler located within the second chamber and at least partially surrounding the osmotic agent. 23. The osmotic drug delivery device of claim 22, wherein the partition includes a movable piston, the osmotic agent includes a tablet, and the first chamber includes a delivery orifice through which the beneficial agent may be delivered from the first chamber to a location external of the delivery device.