Single-use medicine delivery unit for needleless hypodermic injector

• US 5,938,637 A
• Filed: 03/14/1997
• Issued: 08/17/1999
• Est. Priority Date: 03/14/1997
• Status: Expired due to Fees

• Current Assignee: Path
• Original Assignee: Path
• Inventors: Austin, Glenn D., Colburn, Theodore J., Salo, Timothy J.
• Primary Examiner(s): McDermott, Corrine
• Assistant Examiner(s): RODRIGUEZ, CRIS LOIREN
• Application Number:
  US08/819,563
• Time in Patent Office: 886 Days
• Field of Search: 604/68, 604/72, 604/140, 604/141, 604/143, 604/147, 604/152, 604/154, 604/157, 604/257, 604/261, 604/228, 222/340, 222/372, 222/153.05, 222/341, 222/320, 222/575
• US Class Current: 604/72
• CPC Class Codes: A61M 5/30 Syringes for injection by jet action, without needle, e.g. for use with replaceable ampoules or carpules
• CPC Class Codes: A61M 5/50 having means for preventing re-use, or for indicating if defective, used, tampered with or unsterile retractable needles or needle protectors with means for preventing re-use A61M5/321

Abstract

A disposable medicine delivery unit for use in a needleless hypodermic injector is configured to allow economical replacement, after each injection, of a patient contact surface and the entire injection flow-path of the medicament, to thereby ensure sterility with less need for repeated equipment cleaning and sterilization procedures. The delivery unit includes a piston seal configured to prevent improper reuse. The piston seal deforms and sticks in a conical end of the medicine delivery chamber at the end of its injection stroke. A push-only connection between the piston seal and a piston drive rod of the injector ensures that the latter cannot be used to retract the former. Preferably, the piston seal also includes a protruding nipple which enters and destroys the injection orifice following an injection, to further disable the delivery unit.

Claims

1. A disposable medicine delivery unit for a needleless hypodermic injector, comprising:

sidewalls defining an elongated medicine chamber;

a releasable lock device connected to said sidewalls for detachably mounting the delivery unit to a main injector housing;

a discharge nozzle connected with said sidewalls at a distal end of said medicine chamber, a distal end region of said medicine chamber adjacent said nozzle having a reduced cross-sectional area; and

a discharge piston seal slidably mounted for axial movement within said medicine chamber from a first position adjacent a proximal end of said medicine chamber to a second position within said distal end region of the medicine chamber, said piston seal being configured relative to said distal end region of the medicine chamber such that it enters said end region and is securely retained therein, with a holding strength increased relative to the frictional forces resisting sliding of the piston seal out of said first position, at the end of its injection stroke;

wherein said distal end region of the medicine chamber is defined by conically tapered interior walls of said discharge nozzle, and said piston seal has a mating but slightly larger conical distal end portion for receipt within said distal end region with an interference fit.

2. The disposable medicine delivery unit according to claim 1, wherein said sidewalls further define a medicine fill port adjacent said proximal end of said medicine chamber, said medicine fill port being adapted to be connected to a source of liquid medicament.

3. The disposable medicine delivery unit according to claim 1, wherein said piston seal permanently deforms upon entry into said end region.

4. The disposable medicine delivery unit according to claim 1, wherein said discharge nozzle comprises an injection orifice and said piston seal comprises a protrusion extending from a distal end thereof and aligned with said injection orifice, said protrusion extending into and permanently deforming said injection orifice when said piston seal reaches the end of its injection stroke.

5. The disposable medicine delivery unit according to claim 1, wherein said piston seal comprises at least one circumferential sealing fin which flares outwardly against said sidewalls under pressure generated in said medicine chamber during an injection.

6. The disposable medicine delivery unit according to claim 1, further comprising a collar surrounding said discharge nozzle and serving to position said nozzle with respect to a skin surface of an injection recipient.

7. The disposable medicine delivery unit according to claim 6, wherein said discharge nozzle comprises a distal end surface and said collar lies substantially flush with said distal end surface, so as to position said surface in low force contact with the skin surface when said collar is pressed against the skin surface.

8. The disposable medicine delivery unit according to claim 6, wherein said collar extends slightly beyond a distal end surface of the discharge nozzle, to pre-position the nozzle in slightly spaced relation to said skin surface.

9. The disposable medicine delivery unit according to claim 8, wherein said collar defines a passageway to vent the space between the skin surface and distal end surface of the discharge nozzle.

10. The disposable medicine delivery unit according to claim 8, wherein said discharge nozzle comprises an injection orifice having an acute proximal edge.

11. The disposable medicine delivery unit according to claim 10, wherein said injection orifice tapers slightly in a proximal direction from said distal end surface.

12. The disposable medicine delivery unit according to claim 1, wherein said releasable lock device comprises a shoulder flange forming part of a bayonet-type releasable lock device.

13. The disposable medicine delivery unit according to claim 1, wherein said releasable lock device, said sidewalls and said discharge nozzle are molded as a single piece from medical grade commodity polymer.

14. The disposable medicine delivery unit according to claim 13, wherein said medical grade commodity polymer is a medical grade modified styrene.

15. The disposable medicine delivery unit according to claim 14, wherein said modified styrene is substantially clear.

16. The disposable medicine delivery unit according to claim 14, wherein said medical grade commodity polymer is a butadiene styrene polymer.

17. The disposable medicine delivery unit according to claim 13, wherein said commodity polymer has a flexural modulus of approximately 205,000 psi.

18. The disposable medicine delivery unit according to claim 1, wherein said piston seal is injection molded as a single piece of semi-flexible medical grade polymer.

19. The disposable medicine delivery unit according to claim 18, wherein said medical grade polymer is a polyolefin.

20. The disposable medicine delivery unit according to claim 18, wherein said medical grade polymer has a flexural modulus of approximately 130,000 psi.

21. The disposable medicine delivery unit according to claim 18, wherein said medical grade polymer has a tensile strength of less than 4000 psi.

22. The disposable medicine delivery unit according to claim 1, said disposable medicine delivery unit comprising a sealed cartridge pre-filled with medicament.

23. A needleless hypodermic injector assembly, comprising:

a main injector housing containing a reciprocable driving member and a discharge rod attached to said driving member; and

a disposable medicine delivery unit, said delivery unit including;

sidewalls defining an elongated medicine chamber and a medicine fill port adjacent a proximal end of said medicine chamber, said fill port being adapted to be connected to a source of liquid medicament;

a releasable lock device connected to said sidewalls and detachably mounting the delivery unit to said main injector housing;

a discharge nozzle connected with said sidewalls at a distal end of said medicine chamber; and

a discharge piston seal slidably mounted for axial movement within said medicine chamber from a first proximal position adjacent said medicine fill port to a second distal position within an end region of the medicine chamber adjacent said discharge nozzle, said piston seal having a proximal end surface engageable in a push-only relation with a distal end of said discharge rod when said delivery unit is mounted in the main injector housing;

wherein said end region of the medicine chamber has a reduced cross-sectional area and said piston seal is configured relative to said end region such that it enters said end region and is securely retained therein, with a holding strength increased relative to the frictional forces resisting sliding of the piston seal out of said first proximal position, at the end of its injection stroke.

24. The needleless hypodermic injector assembly according to claim 23, wherein said distal end region of the medicine chamber is defined by conically tapered interior walls of said discharge nozzle, and said piston seal has a mating by slightly larger conical distal end portion for receipt within said end region with an interference fit.

25. The injector assembly according to claim 23, wherein said main injector housing further contains:

an air chamber, said driving member comprising a driving piston slidably mounted in said air chamber;

a line extending from said air chamber for connecting the air chamber with a source of pressurized air, and an injection actuator operatively connected to said line for selectively admitting pressurized air from said source into said air chamber to actuate the driving piston.

26. The injector assembly according to claim 25, said main injector housing further comprising a compression spring and a passageway configured to receive said medicine delivery unit, said spring being attached to said driving piston and extending coaxially with said discharge rod into said passageway, said compression spring having a platform attached at its distal end, said platform further having an axial bore for free travel of said discharge rod therethrough, whereby when said delivery unit is mounted in said main housing, said compression spring biases said driving piston, and the attached discharge rod, in the proximal direction.

27. A disposable medicine delivery unit for a needleless hypodermic injector, comprising:

sidewalls defining an elongated medicine chamber;

a releasable lock device connected to said sidewalls for detachably mounting the delivery unit to a main injector housing;

a discharge nozzle connected with said sidewalls at a distal end of said chamber, a distal end region of said chamber adjacent said nozzle having a reduced cross-sectional area; and

a discharge piston seal slidably mounted for axial movement within said chamber from a first position adjacent a proximal end of said chamber to a second position within said distal end region of the chamber, said discharge nozzle comprising an injection orifice and said piston seal comprising a protrusion extending from a distal end thereof and aligned with said injection orifice, said protrusion extending into and permanently deforming said injection orifice when said piston seal reaches the end of its injection stroke.

28. A disposable medicine delivery unit for a needleless hypodermic injector, comprising:

sidewalls defining an elongated medicine chamber;

a releasable lock device connected to said sidewalls for detachably mounting the delivery unit to a main injector housing; and

a discharge nozzle connected with said sidewalls at a distal end of said chamber, said discharge nozzle having an injection orifice with an acute proximal edge.

29. A disposable medicine delivery unit according to claim 28, wherein said nozzle comprises a distal end surface and said injection orifice tapers slightly in a proximal direction from said distal end surface.

30. A disposable medicine delivery unit for a needleless hypodermic injector, comprising:

sidewalls defining an elongated medicine chamber;

a releasable lock device connected to said sidewalls for detachably mounting the delivery unit to a main injector housing;

a discharge nozzle connected with said sidewalls at a distal end of said medicine chamber, a distal end region of said medicine chamber adjacent said nozzle having a reduced cross-sectional area; and

a discharge piston seal slidably mounted for axial movement within said medicine chamber from a first position adjacent a proximal end of said medicine chamber to a second position within said distal end region of the medicine chamber, said piston seal being configured relative to said distal end region of the medicine chamber such that it enters said end region and is securely retained therein, with a holding strength increased relative to the frictional forces resisting sliding of the piston seal out of said first position, at the end of its injection stroke;

wherein said sidewalls further define a medicine fill port adjacent said proximal end of said medicine chamber, said medicine fill port being adapted to be connected to a source of liquid medicament.

31. A disposable medicine delivery unit for a needleless hypodermic injector, comprising:

sidewalls defining an elongated medicine chamber;

a releasable lock device connected to said sidewalls for detachably mounting the delivery unit to a main injector housing;

a discharge nozzle connected with said sidewalls at a distal end of said medicine chamber, a distal end region of said medicine chamber adjacent said nozzle having a reduced cross-sectional area; and

a discharge piston seal slidably mounted for axial movement within said medicine chamber from a first position adjacent a proximal end of said medicine chamber to a second position within said distal end region of the medicine chamber, said piston seal being configured relative to said distal end region of the medicine chamber such that it enters said end region and is securely retained therein, with a holding strength increased relative to the frictional forces resisting sliding of the piston seal out of said first position, at the end of its injection stroke;

wherein said piston seal permanently deforms upon entry into said region.

32. A disposable medicine delivery unit for a needleless hypodermic injector, comprising:

sidewalls defining an elongated medicine chamber;

a releasable lock device connected to said sidewalls for detachably mounting the delivery unit to a main injector housing;

a discharge nozzle connected with said sidewalls at a distal end of said medicine chamber, a distal end region of said medicine chamber adjacent said nozzle having a reduced cross-sectional area; and

a discharge piston seal slidably mounted for axial movement within said medicine chamber from a first position adjacent a proximal end of said medicine chamber to a second position within said distal end region of the medicine chamber, said piston seal being configured relative to said distal end region of the medicine chamber such that it enters said end region and is securely retained therein, with a holding strength increased relative to the frictional forces resisting sliding of the piston seal out of said first position, at the end of its injection stroke;

wherein said discharge nozzle comprises an injection orifice and said piston seal comprises a protrusion extending from a distal end thereof and aligned with said injection orifice, said protrusion extending into and permanently deforming said injection orifice when said piston seal reaches the end of its injection stroke.

33. A disposable medicine delivery unit for a needleless hypodermic injector, comprising:

sidewalls defining an elongated medicine chamber;

a releasable lock device connected to said sidewalls for detachably mounting the delivery unit to a main injector housing;

a discharge nozzle connected with said sidewalls at a distal end of said medicine chamber, a distal end region of said medicine chamber adjacent said nozzle having a reduced cross-sectional area;

a discharge piston seal slidably mounted for axial movement within said medicine chamber from a first position adjacent a proximal end of said medicine chamber to a second position within said distal end region of the medicine chamber, said piston seal being configured relative to said distal end region of the medicine chamber such that it enters said end region and is securely retained therein, with a holding strength increased relative to the frictional forces resisting sliding of the piston seal out of said first position, at the end of its injection stroke; and

a collar surrounding said discharge nozzle and serving to position said discharge nozzle with respect to a skin surface of an injection recipient, wherein said collar extends slightly beyond a distal end surface of the discharge nozzle, to pre-position the discharge nozzle in slightly spaced relation to said skin surface, and said discharge nozzle comprises an injection orifice having an acute proximal edge.

34. The disposable medicine delivery unit according to claim 33, wherein said injection orifice tapers slightly in a proximal direction from said distal end surface.