Details for Patent: 8,672,898

Title:	Automatic injection device with reset feature
Abstract:	The present invention relates to a dose setting and expelling device comprising a drive member and a dose setting mechanism which simultaneously sets a given dose and stores the energy necessary for a subsequently driving the drive member in order to expel a dose of medicine from an injection device. According to the invention the dose setting mechanism allows adjustment in both directions, such that a given set dose can be reduced or cancelled by reversing the input motion, typically by rotating a setting member backwardly, this in contrast to the known devices which either requires an additional release mechanism or which cannot be reversed at all.
Inventor(s):	Enggaard; Christian (Hillerod, DK)
Assignee:	Novo Nordisk A/S (Bagsvaerd, DK)
Filing Date:	Oct 22, 2004
Application Number:	10/970,868
Claims:	1. A dose setting device for use in combination with an injection device comprising a fluid-filled reservoir and a drive member having an external thread that engages an axially fixed component within the device having an internal thread, wherein the drive member is adapted to expel a dose of fluid from the reservoir, the dose setting device being adapted for repetitive injection of individually set doses of fluid from the reservoir, the dose setting device comprising: a housing a spring mounted in the housing, wherein the spring acts to store a force for use in creating relative rotational motion between the drive member and the axially fixed component; a dose setting assembly mounted in the housing and connected to the spring, the dose setting assembly comprising a dose setting member being rotatable in a manner to set and adjust the size of a dose, the manner consisting of rotating the dose setting member in a first rotational direction to set the size of the dose and merely rotating the member in a second and opposite direction to reduce the size of the dose, when dose size reduction is necessary, wherein when the dose setting member is rotated in the second direction to reduce the size of a set dose, no drug is expelled from the device, wherein selectively reducing the size of the set dose consists solely of rotating the dose setting member in a second direction opposite that of the first direction a first direction and wherein rotating in the first direction is against the bias of the spring and results in the storage of energy in the spring for later use in expelling a drug from the reservoir, wherein during dose setting and adjusting the dose setting member does not move axially, a releaseable latch adapted to retain the dose setting member in the set position against the bias of the spring, wherein release of the latch causes the spring in the dose setting assembly to drive the drive member to thereby expel a set dose from a fluid-filled reservoir in the injection device when the dose-setting device is used in combination therewith, the force for expelling the set dose being provided by the spring, wherein release of the latch causes the spring to induce a relative rotational motion between the drive member and the axially fixed component having the internal thread thereby driving the drive member in a distal direction, and wherein numbers are printed along a helical line to form a scale on an external surface of a rotatable skirt so that only a portion of the numbers pass through a window in the housing during the setting of a dose, during dose size reduction without expulsion and during expulsion of a dose during injection from the fluid-filled reservoir, when the skirt rotates. 2. A dose setting device as defined in claim 1, further comprising a fluid-filled reservoir having a foremost end adapted to cooperated with an injection needle and a rearmost end closed by a piston in sliding engagement with an internal surface of the reservoir, the drive member being the in the form of a piston drive member adapted to engage the piston to thereby expel a dose of liquid as the drive member is moved forwardly by the spring. 3. A dose setting device as defined in claim 1, wherein the dose setting assembly further comprises a coupling member (60) in displaceable engagement with the dose setting member, the spring acting on the coupling member, the coupling member acting on the dose setting member (50). 4. A dose setting device as defined in claim 3, wherein the dose setting member (50) and the coupling member (60) comprise mutually cooperating surfaces (54, 62) providing a coupling there between such that movement of the dose setting member in order to set a dose results in straining of the spring. 5. A dose setting device as defined in claim 4, wherein one of the dose setting member (50) and the coupling member (60) is rotationally mounted on the drive member, the other being arranged in sliding, non-rotational engagement with the drive member. 6. A dose setting device as defined in claim 5, wherein the dose setting member (50) is rotationally mounted on a threaded portion of the drive member whereby selectively setting a dose results in an axial movement of the dose setting member relative to the drive member, and the coupling member (60) is arranged in sliding, non-rotational engagement with the drive member, the spring acting on the coupling member in a direction corresponding to the longitudinal axis of the drive member. 7. A dose setting device as defined in claim 6, wherein the threaded connection between the dose setting member and the drive member is of the non-locking type, and wherein the coupling (54, 62) between the dose setting member and the coupling member allows the dose setting member to be rotated in either direction, yet preventing the spring to counter rotate the dose setting member. 8. A dose setting device as defined in claim 5, wherein the coupling (54, 62) is arranged between the cooperating surfaces of the dose setting member (50) and the coupling member (60), the coupling providing a resistance against rotation which is sufficiently to prevent the spring to counter rotate the dose setting member, the resistance being easily overcome by a user rotating the dose setting member in either direction, whereby a user can selectively increase or decrease a dose setting. 9. A dose setting device as defined in claim 3, further comprising a threaded member (20) with a first internal thread, the drive member being a longitudinal drive member (30) having an external thread (31) corresponding to the first internal thread, the threads being non-locking having a pitch angle whereby axial movement of the drive member is obtained by an axial force applied to the drive member by the spring. 10. A dose setting device as defined in claim 1, further comprising a threaded member (20) fixed in the housing and comprising a first internal thread, the drive member being a longitudinal piston drive member (30) having an external thread (31) corresponding to the first internal thread, the threads being non-locking having a pitch angle whereby axial movement of the piston drive member is obtained by an axial force applied to the piston drive member by the spring. 11. A dose setting device as defined in claim 10, wherein the dose setting member (50) comprises a second internal thread (53), the dose setting member being rotationally mounted on the external thread (31) of the piston drive member, whereby selectively setting a dose results in an axial movement of the dose setting member relative to the piston drive member. 12. A dose setting device as defined in claim 11, wherein the dose setting assembly further comprises a coupling member (60) arranged in sliding, non-rotational engagement with the piston drive member, the spring acting on the coupling member in a direction corresponding to the longitudinal axis of the drive member, the coupling member acting on the dose setting member (50). 13. A dose setting device as defined in claim 12, wherein the dose setting member (50) and the coupling member (60) comprise mutually cooperating surfaces (54, 62) providing a coupling there between such that rotation of the dose setting member in order to set a dose results in straining of the spring as the coupling member is driven backwardly. 14. A dose setting device as defined in claim 13, wherein the threaded connection between the dose setting member and the piston drive member is of the non-locking type, and wherein the coupling (54, 62) between the dose setting member and the coupling member allows the dose setting member to be rotated in either direction, yet preventing the spring to counter rotate the dose setting member. 15. A dose setting device as defined in claim 13, wherein the coupling (54, 62) is arranged between the cooperating surfaces of the dose setting member (50) and the coupling member (60), the coupling providing a resistance against rotation which is sufficiently to prevent the spring to counter rotate the dose setting member, the resistance being easily overcome by a user rotating the dose setting member in either direction, whereby a user can selectively increase or decrease a dose setting. 16. A dose setting device as defined in claim 15, wherein the coupling between the dose setting member and the coupling member is provided by coupling parts having surfaces provided with sector shaped teeth (54, 62) having ramp shaped edges, the surfaces being forced against each other with the ramp shaped edges of the teeth on one surface abutting the ramp shaped edges of the teeth on the other surface, such that when the dose setting member is rotated in either direction, the teeth on the coupling parts will slide with their ramp shaped parts over each other, whereby the dosing member is axially displaced against the force of the spring and will jump back each time a top of the teeth is reached, the pitch of the toothing being chosen so that a jump back takes place each time the dose setting is increased by a given dose unit. 17. A dose setting device as defined in claim 14, wherein the coupling is a frictional coupling provided between the cooperating surfaces, the necessary compression force between the surfaces being provided by the spring acting on the coupling member. 18. A dose setting device as defined in claim 1, wherein the latch (80, 90) acts on the drive member. 19. A dose setting and drive mechanism for use in a drug delivery device having a housing and containing fluid-filled reservoir, the dose setting and drive mechanism comprising: a threaded drive member adapted to expel a dose of fluid from the reservoir, the threaded drive member threadedly engaging a non-axially displaceable element, wherein relative rotational motion between the drive member and the non-axially displaceable element induces a distal motion of the drive member to expel the dose; an elastic element for storing energy, a dose setting mechanism that cooperates with the elastic element, the dose setting mechanism comprising a dose setting element that is capable of being rotatable in a dose setting manner consisting of rotating the dose setting member in a first direction to a selected set position, against a bias of the elastic element, wherein rotation of the dose setting member stores energy in the elastic element for later use in expelling a drug from the reservoir, and in a second manner to reduce the size of the set dose, when necessary, the second manner consisting solely of rotating the dose setting member in a second direction opposite the first direction to selectively adjust the set position to reduce the size of the set dose without expelling medication from the device, wherein the dose setting member does not move axially with respect to the housing, a releaseable latch adapted to retain the dose setting member in the set position against the bias of the elastic element, wherein release of the latch causes the dose setting assembly to drive relative rotational motion between the drive member and the threaded non-axially displaceable element which thereby expels a set dose from a fluid-filled reservoir when the dose-setting device is used in combination therewith, the force for expelling the set dose being provided by the elastic element, wherein numbers are printed along a helical line on an external surface disposed on the dose setting member so that only a portion of the numbers pass through a window (17) during the setting of a dose, reduction of the size of a set dose, and expulsion of a dose from the fluid-filled reservoir. 20. An injection syringe for apportioning and injecting multiple doses of medication from a drug containing reservoir the injection syringe, the injection syringe comprising: a dose setting knob that is rotatable but not axially displaceable, a dose indicator having a helically arranged scale of numbers, a window for displaying one of the helically arranged numbers, a latch, an elastic energy storing member for storing a sufficient amount of energy to expel a set dose of medication, the elastic energy storing member storing a force that induce a rotational motion between two threaded components to create an axial movement of a member that transfers force to the drug containing reservoir, wherein the dose setting knob is manipulatable in a manner to set and selectively reduce the size of a set dose, when necessary, the manner consisting of rotating the dose setting knob in a first direction to set a dose, wherein rotation of the dose setting knob in the first direction stores energy in the elastic member, wherein the dose setting knob is freely rotatable in an opposite direction without the need for additional operations by a user, wherein rotation of the dose setting member in the opposite direction acts to reduce the size of the set dose without expelling medication, thereby allowing the user to selectively adjust the set dose downward without expelling medication, wherein when the latch is actuated it causes release of energy from the elastic member and wherein the released energy from the elastic member is transferred to a reservoir containing medication thereby expelling medication from the reservoir, wherein during the expelling of medication as the dose indicator rotates toward a zero position, which is the position that the scale was in prior to setting a dose, and wherein the rotation of the scale of numbers relative to the window is visible in the window during setting, reducing and the expelling of a dose of medication and wherein only a portion of the numbers is visible in the window at any one time. 21. An injection pen comprising: a housing; a distal end for affixing an injection needle and a proximal end; a rotatable dose setting element, the dose setting element rotable with respect to the housing but axially fixed with respect to the housing; a dose indicator assembly comprising a scale of numbers; a window disposed on the injection pen through which at least one number on the scale of numbers is visible; a threaded plunger rod having an external threaded surface and being drivable in a proximal direction to expel drug from the pen; a threaded element axially fixed with respect to the housing and threadedly engaging the plunger rod element such that a relative rotational motion occurring between the threaded element and the plunger rod moves the plunger rod distally with respect to the housing; a spring for storing energy inputted by a user by rotation of the dose setting element, the spring imparting sufficient energy to expel a dose of medication from the pen by causing the required relative rotation between the plunger rod and the threaded element wherein a torsional force is applied to one or both of the plunger rod or threaded element, the torsional force being supplied by the energy in the spring; a latch, wherein when the latch is in a first position energy may be stored in the spring and wherein when the latch is moved to a second position energy is released from the spring to expel medication from the injection pen; wherein during setting of a dose the dose setting element is rotated against the bias of the spring and results in the storage of energy in the spring, wherein the energy is of a sufficient amount to drive the set dose from the pen upon release of the latch; wherein during injection of medication, the latch is actuated to release the energy in the spring and wherein a relative rotational motion occurs between the plunger rod and the threaded element and the plunger rod advances axially; wherein during dose setting the dose indicator rotates with the dose setting element away from an initial position and wherein during ejecting of a dose when the latch is released, the dose indicator automatically rotates toward the initial position while the dose is being expelled from the device such that upon completion of ejection the dose indicator is back at the initial position, which is a zero position; wherein the dose setting element dose not move axially with respect to the housing during dose setting or ejecting of a dose and wherein the distal and proximal ends of the pen do not move axially with respect to the housing; wherein the dose setting element is rotatable in a manner to set and to adjust a set dose, the manner comprising rotating the dose setting element in a first direction to set a dose and rotating the dose setting element in a second direction to reduce the size of the set dose without expelling medication from the pen; wherein when the dose setting element rotates relative to the window during dose setting, dose adjusting and ejecting, the scale is visible in the window such that at least some of the numbers on the scale are visible in the window and wherein during dose setting, dose adjusting and ejecting the numbers pass through the window. 22. The pen of claim 21, wherein the threaded element rotatable with respect to the housing and wherein the plunger rod does not rotate with respect to the housing during dose ejecting. 23. The pen of claim 21, wherein the threaded element is rotatably fixed with respect to the housing and wherein the plunger rod rotates during ejection of the housing. 24. The pen of claim 21, wherein the manner to set and to adjust a set dose consists of rotating the dose setting element in a first direction to set the dose and merely rotating the dose setting element in a second direction to reduce the size of the set dose and the scale of numbers is a helically arranged scale. 25. The pen of claim 21, wherein the manner to set and to adjust a set dose consists of rotating the dose setting element in a first direction to set the dose and merely rotating the dose setting element in a second direction to reduce the size of the set dose. 26. The pen of claim 22, wherein the dose indicator rotates less than one full revolution.