Osmotic delivery system having space efficient piston

1. An osmotic delivery system comprising:

an enclosure, said enclosure having an interior for holding a beneficial agent, said interior having an interior surface;

an osmotic agent located in said interior;

a semipermeable body in liquid communication with said enclosure for permitting liquid to permeate through said semipermeable body to said osmotic agent; and

a piston located within said interior of said enclosure, being movable with respect to said interior of said enclosure, defining a movable seal with said interior of said enclosure that separates said osmotic agent from said beneficial agent, and having a recess that receives a sleeve having an interior that receives at least a portion of said osmotic agent, said osmotic agent located between said piston and said semipermeable body, said osmotic agent for imbibing liquid from a surrounding environment through said semipermeable body to cause said piston to move and in turn cause delivery of said beneficial agent from said enclosure, wherein said osmotic agent consists of a semisolid or a solid.

2. The osmotic delivery system according to claim 1 , wherein said osmotic agent is in the form of a tablet, pellet, or powder at least partially within said recess.

3. The osmotic delivery system according to claim 1 , wherein said interior of said enclosure includes said interior surface, said piston abutting against said interior surface.

4. The osmotic delivery system according to claim 1 , wherein said semipermeable body is located at least partially within said interior of said enclosure.

5. The osmotic delivery system according to claim 1 , wherein said enclosure includes an opening and said semipermeable body includes a semipermeable plug, said semipermeable plug located at least partially within said opening.

6. The osmotic delivery system according to claim 1 , wherein said enclosure includes an opening and said semipermeable body includes a semipermeable membrane, said semipermeable membrane located at least partially within said opening.

7. The osmotic delivery system according to claim 1 , wherein said enclosure is a capsule.

8. The osmotic delivery system according to claim 1 , wherein said enclosure includes a cylindrical tube.

9. The osmotic delivery system according to claim 1 , wherein said osmotic agent is located between said semipermeable body and said piston.

10. The osmotic delivery system according to claim 1 , wherein a portion of said osmotic agent is located outside of said recess.

11. The osmotic delivery system according to claim 1 , wherein said piston is cup-shaped.

12. The osmotic delivery system according to claim 1 , wherein said recess is cylindrical.

13. The osmotic delivery system according to claim 1 , wherein said recess is a square cavity, concave indentation, conical pit, gouge, or depression.

14. The osmotic delivery system according to claim 1 , wherein said piston includes at least one rib for effecting a movable seal with said enclosure.

15. The osmotic delivery system according to claim 1 , wherein said piston includes a plurality of ribs for effecting said movable seal with said interior.

16. The osmotic delivery system according to claim 1 , wherein said sleeve is cup-shaped.

17. The osmotic delivery system according to claim 1 , wherein said beneficial agent is located in said interior of said enclosure, said beneficial agent being delivered from said enclosure when said piston moves.

18. The osmotic delivery system according to claim 1 , wherein said beneficial agent is located in said interior of said enclosure, said piston defining said movable seal that separates said osmotic agent from said beneficial agent.

19. The osmotic delivery system according to claim 1 , further comprising: an opening in said enclosure; and a plug located in said opening, said plug having a delivery port for delivery of said beneficial agent from the interior of said capsule.

20. The delivery system according to claim 1 , further comprising: a delivery port in said enclosure for delivery of said beneficial agent from the interior of a capsule.

21. The osmotic delivery system according to claim 1 , wherein said osmotic agent comprises an osmagent or an osmopolymer.

22. The osmotic delivery system according to claim 1 , wherein said osmotic agent is magnesium sulfate, magnesium chloride, potassium sulfate, sodium chloride, sodium sulfate, lithium sulfate, sodium phosphate, potassium phosphate, d-mannitol, sorbitol, inositol, urea, magnesium succinate, tartaric acid, raffinose, sucrose, glucose, lactose, fructose, dextran, poly(hydroxy-alkyl methacrylates) with molecular weight of about 30,000 to about 5,000,000, poly(vinylpyrrolidone) with molecular weight of about 10,000 to about 360,000, anionic and cationic hydrogels, polyelectrolyte complexes, poly(vinyl alcohol) having low acetate residual, optionally cross-linked with glyoxal, formaldehyde or glutaraldehyde and having a degree of polymerization of about 200 to about 30,000, a mixture of methyl cellulose, cross-linked agar and carboxymethylcellulose, a mixture of hydroxypropyl methylcellulose and sodium carboxymethylcellulose, a polymer of N-vinyllactams, polyoxyethylene-polyoxypropylene gels, a polyoxybutylene-polyethylene block copolymer gel, carob gum, polyacrylic gel, polyester gel, polyurea gel, polyether gel, polyamide gel, polypeptide gel, polyamino acid gel, polycellulosic gel, carbopol acidic carboxy polymer having a nolecular weight of about 250,000 to about 4,000,000, Cyanamer polyacrylamide, cross-linked indene-maleic anhydride polymer, polyacrylic acid having a molecular weight of about 80,000 to about 200,000, Polyox Polyethylene oxide polymer having a molecular weight of about 100,000 to about 5,000,000, starch graft copolymer, or an acrylate polymer polysaccharide.