Injection device

• US 8,333,739 B2
• Filed: 10/31/2007
• Issued: 12/18/2012
• Est. Priority Date: 06/16/2000
• Status: Expired due to Term

• Current Assignee: Novo Nordisk A/S
• Original Assignee: Novo Nordisk A/S
• Inventors: Møller, Claus Schmidt
• Primary Examiner(s): STIGELL, THEODORE J
• Application Number:
  US11/931,010
• Publication Number:
  US 20080065026A1
• Time in Patent Office: 1,875 Days
• Field of Search: 604207-211, 604/181, 604/187, 604/218, 604/224
• US Class Current: 604/207
• CPC Class Codes: A61M 2005/3152 including gearings to multiply or attenuate the piston displacing force
• CPC Class Codes: A61M 2205/581 by audible feedback
• CPC Class Codes: A61M 5/24 Ampoule syringes, i.e. syringes with needle for use in combination with replaceable ampoules or carpules, e.g. automatic ampoules or carpules A61J1/06
• CPC Class Codes: A61M 5/28 Syringe ampoules or carpules, i.e. ampoules or carpules provided with a needle
• CPC Class Codes: A61M 5/315 Pistons; Piston-rods; Guiding, blocking or restricting the movement of the rod or piston; Appliances on the rod for facilitating dosing ; Dosing mechanisms
• CPC Class Codes: A61M 5/31541 Means preventing setting of a dose beyond the amount remaining in the cartridge
• CPC Class Codes: A61M 5/3155 by rotational movement of dose setting member, e.g. during setting or filling of a syringe
• CPC Class Codes: A61M 5/31551 including axial movement of dose setting member
• CPC Class Codes: A61M 5/31558 using scaling up or down transmissions, e.g. gearbox
• CPC Class Codes: A61M 5/31575 using scaling up or down transmissions, e.g. gearbox
• CPC Class Codes: A61M 5/3158 performed by axially moving actuator operated by user, e.g. an injection button

Abstract

A medication dispensing device with a housing and a member wherein the member is moveable in a distal direction is useful in delivering medication to a patient. A fluid container can be used with the device and often has a moveable piston at one end and an outlet at the other. The member receives a force from a user and drives the piston in the distal direction to expel medication. A intermediate system is disposed between the member and the piston including a gear set that has a pinion in meshed engagement with a rack. The system allows the member to move a greater distance than the piston moves thereby increasing the force on the piston.

Claims

1. A method for expelling medication from a prefilled cartridge having an end closed by a piston wherein the cartridge is contained in an injection device having a rack and pinion gearbox assembly that couples an injection button with a piston driver;

the method comprising the steps of;

setting a dose to be injected from the prefilled cartridge;

moving a first rack, which contains teeth, in a proximal direction, away from the cartridge and injecting end of the device during setting of a dose, the rack remaining in continuous meshed engagement with a pinion which during the setting of the dose causing the pinion to rotate in a first direction;

moving the pinion in a proximal direction away from an injecting end of the device during the setting of the dose

moving the first rack distally, which is toward, the injecting end of the device during injection of a dose and causing the pinion to rotate in an opposite direction and to move forward, thereby causing part of the transmission to drive the piston driver which in turn moves the piston within the cartridge and expels medication from the device.

2. The method of claim 1, further comprising the step of:

rotating a second pinion at the same speed as the pinion of claim 1 during the expelling of the medication,

wherein the second pinion is in continuous meshed engagement with a second rack.

3. The method of claim 2, wherein the first rack moves distally by a distance greater than the piston is driven distally during injection.

4. A method for injecting medication comprising the steps of:

providing a medication delivery device having a housing for containing a prefilled cartridge of medication having a moveable piston at one end, wherein the device further comprises a plunger element (19) for receiving an injection force from a user, a gear set comprised of at least a first and second gear wheel that revolve around a common axis and wherein the first gearwheel is in continuous meshed engagement with a first toothed rack that is coupled to the plunger element so that the rack substantially moves in unison with the plunging element when it moves distally and proximally, wherein the second gear wheel is in continuous meshed engagement with a second rack;

moving the plunger element proximally while setting a dose of medication to be injected from the cartridge;

exerting a force on the plunger element in a distal direction, the force being large enough to drive the plunging element forward;

moving the plunging element and the first rack in a distal direction as a result of the exerted force being applied to the plunging element;

rotating the gear wheels as the first rack is moved distally;

moving the gear wheels distally during injection when the plunging element is being depressed;

moving the piston forward, wherein the piston moves a lesser distance than the first rack, wherein it moves the lesser distance as a result of a gearing created by the first and second racks and the first and second gear wheels.

5. A method for injecting a device that has a housing and contains a prefilled cartridge of medication, wherein the cartridge is closed at one end by a moveable piston, the method comprising the steps of:

setting a dose by;

moving a plunging rack in a proximal direction to set a dose to be injected;

rotating a gear set comprised of at least one pinion gear wheel during dose setting wherein the pinion gear wheel is in continuous meshed engagement with the plunging rack

injecting the set dose by;

moving the plunging rack in a distal direction toward an injecting end of the device;

causing the pinion gear wheel to rotate during movement of the plunging rack;

transferring a force to a piston driver from the plunging rack through the gear set to a piston driver to expel medication;

wherein the gear set moves longitudinally within the device during dose setting and dose injecting.

6. A method for injecting medication from a medication device have a housing and having a prefilled cartridge of medication which is closed at one end by a moveable piston, the method comprising the steps of:

setting a dose of medication to be injected by rotating a dose scale drum away from an initial position to set the dose size;

during rotation of the dose scale drum, moving a plunging rack that contains teeth in a proximal direction, which is away from the injecting end of the device;

rotating a gear wheel during movement of the rack, the gear wheel being in constant meshed engagement with the plunging rack;

moving the gear wheel proximally;

moving the plunging rack distally;

rotating the dose scale drum toward the initial position during the distal movement of the plunging rack so that the drum reaches the initial position upon completion of the injection.