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Fixed dose medication dispensing device

  • US 7,695,454 B2
  • Filed: 10/15/2004
  • Issued: 04/13/2010
  • Est. Priority Date: 10/16/2003
  • Status: Expired due to Fees
First Claim
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1. A medication dispensing apparatus comprising:

  • a housing;

    an axially extending screw element rotatably and axially fixed within said housing during dose preparing, and rotatably fixed and axially movable in a distal direction relative to said housing during dose injecting, said screw element including a threaded shaft;

    a fluid container defining a medicine-filled reservoir with a movable piston at one end and an outlet at the other end, said piston engagable by said screw element to be advanced toward said outlet when said screw element is moved distally;

    a nut threadedly engaged with the screw element shaft to be axially movable relative thereto during rotation of said nut relative to said screw element;

    a nut driver rotatably and axially shiftable relative to said housing;

    wherein said nut and said nut driver include cooperating elements which when engaged rotatably lock together said nut and said nut driver, and which when disengaged permit relative rotation of said nut and said nut driver;

    a guide disposed on one of said nut driver and said housing;

    a follower disposed on the other of said nut driver and said housing;

    wherein said guide and follower comprise a surface abutting relationship to promote a user moving said nut driver relative to said housing along a travel path that operates the apparatus, said travel path including a dose preparing section and a dose injecting section, said dose preparing section including a reset segment, a nut engaging segment, and a nut rotating segment connected in sequence, and wherein said injecting section connects said nut rotating segment with said reset segment;

    wherein said cooperating elements of said nut and said nut driver are disengaged when said nut driver is disposed in said reset segment;

    wherein said cooperating elements of said nut and said nut driver become engaged when said nut driver is shifted through said nut engaging segment from said reset segment to said nut rotating segment;

    wherein the engagement of said cooperating elements of said nut and said nut driver cause said nut to screw proximally along said threaded shaft when said nut driver is shifted through said nut rotating segment from said nut engaging segment to said injecting section;

    wherein when said nut driver is shifted through said injecting section from said nut rotating segment to said reset segment, said nut and said screw element are shifted in the distal direction to axially advance said fluid container piston to dispense medicine from said outlet, and said cooperating elements of said nut and said nut driver become disengaged; and

    said guide including a hard stop for said follower to define an end of said reset segment of said travel path, and said hard stop when abutted by said follower rotationally aligns said nut driver with said nut engaging segment of said travel path, wherein along said injecting section of said travel path, said guide comprises first and second surfaces that define a channel in which said follower is slidable, said surfaces during injecting serving as physical stops to prevent rotation of said nut driver by abutment by said follower until an injection is complete, wherein along said nut rotating segment of said travel path, said guide comprises third and fourth surfaces that define a channel in which said follower is slidable, said third surface providing a distal barrier during nut rotating that prevents distal plunging of said nut driver by abutment by said follower until said follower passes from said nut engaging segment to said injecting section, thereby limiting misuse of the apparatus.

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