An automatic injection device with a top release mechanism

The invention relates to an automatic, manual, mechanical injection device in which injection of a set dose of a medicament is initiated by actuating a firing member disposed on the upper surface or near the upper surface of the injection device.

Background of the Invention [0002] Automatic injection devices have been previously disclosed in the patent literature. Automatic injection devices contain a type of energy storage in which electric or mechanical energy can be stored. The accumulated energy is easily released by triggering the triggering mechanism and the stored energy helps the user inject the set dose of the drug and / or helps to insert the needle.

[0003] For example, EP 0 516 473 A1 discloses an injection device having a needle which, when the device is operated, is first ejected, a fluid is then expelled through it and finally the needle is automatically withdrawn. The needle is attached to the front portion of the capsule, the capsule can slide longitudinally within the barrel body, the relatively weak spring normally holds the capsule and the needle in the retracted position. The stronger spring acts opposite to the plunger, which, when it is released, fires the capsule forward, acting on the fluid it contains and then squeezes the fluid through the extended needle. At the end of the forward stroke, the plunger and the capsule are disengaged and the weak spring returns the used capsule and needle to the retracted position.

[0004] WO 01/41838 discloses a manual injection device by means of which a set dose of a fluid medication can be injected from a medicament reservoir, such as a cylindrical ampule, by firing a reservoir of energy in the device. The energy reserve may be either an electric battery that can be powered by the motor to squeeze the set dose of the medication, or a compressed spring held in its position compressed by the latch. When the spring is triggered, it can squeeze out the set dose of medication. When the energy store is triggered, the liquid medication will be squeezed out of the tubular ampoule by an injection needle mounted on a cylindrical ampoule or on an injection device holding the tubular ampoule. The energy storage is triggered completely or partly by triggering the trigger button, such as an electric switch placed on the casing of the injection device in the further half of the length of the injection device. By forming at least a third distal portion of the injection device with an ergonomic cross-section, the user can grip the injection device, such as a pencil, a thumb, an index finger and a middle finger.

[0005] In both EP 0 516 473 A1 and WO 01/41838, the triggering buttons are arranged on the outer surface of the injection devices. In EP 0 516 473 A1 the trigger button is arranged on the outside of the cylindrical body, whereas in WO 01/41838 the trigger button is located close to the injection needle of the injection device. However, it may be advantageous to arrange the button or trigger mechanism so that the injection device can be actuated by applying a force to the upper region of the injection device, preferably to a button or a firing mechanism arranged along the axis of the injection device.

[0006] WO 94/13343 A discloses a manual injection device according to the preamble of claim 1. It is an object of the invention to provide an automatic, manual, mechanical injection device having a combined trigger and dose setting element. It is a further object of the invention to provide an automatic, manual, mechanical injection device in which injection of the set dose can be initiated by a thumb or index finger of the hand holding the injection device by applying an axial force to the upper region of the injection device.

[0007] Still a further object of the invention is to provide an automatic manual mechanical injection device with an external appearance very similar to traditional hand-held injection devices.

Summary of the Invention [0008] The above-mentioned objects are met by providing in a first aspect a manual injection device by which set doses of a liquid medicament can be injected from a medicament reservoir through an injection needle after the energy reservoir is released in the device; the energy reservoir is adapted to total or partial triggering by triggering a user-operated triggering element placed on or near the upper end of the injection device. The upper end is the end of the injection device that is opposite to the injection needle, the energy reservoir being adapted to be driven by the rotation of the rotatably mounted dose setting element.

[0009] The amount of energy delivered to the energy store may depend on the rotation angle of the dose setting element. Thus, a rather limited rotation of the dose setting element provides a relatively small amount of energy to the energy store, while a large rotation of the dose setting element provides a relatively large amount of energy to the energy store.

[0010] The firing member may be located less than one-fifth or one-sixth of the length of the injection device from the upper end. Alternatively, the firing member may be disposed axially with respect to the injection device such that the firing member forms a push trigger member on the upper surface of the injection device.

[0011] The firing member may be operatively connected to the dose setting element of the injection device such that the firing member may connect to the dose setting element by a key-operated connection when the dose setting member is in the dose setting position. The triggering element may be triggered from the wedge-and-groove connection to the dose setting element when the dose setting member is in the dose injection position. In this arrangement, the manual injection device has no external parts or rotating elements.

[0012] The energy store may be a spring element, such as a torsion spring or a simple spring, the spring element, when it is released, is adapted to squeeze a set dose of medicament from the medicament container through the injection needle. The triggering element may be operatively connected to a release mechanism adapted to trigger the spring element when said triggering element is activated. The trigger element can have an ergonomic shape, adapted to be actuated by the user's thumb or forefinger.

[0013] The medicament container can be a cylindrical ampule having a first and a second end, the first end being closed by a perforated membrane that can be punctured by the first end of the injection needle when the needle is mounted on the device. The other end of the injection needle can be sharpened so that it can puncture the skin at the site where injection is to be made. The other end of the ampoule can be closed by a plunger that can be pressed into the ampoule, squeezing the medicine through the needle.

[0014] The hand-held injection device may further comprise a pivotable drive element adapted to at least partially connect with at least a portion of the drive path of the respective piston rod, the drive member is adapted to be placed in the first axial position when the dose setting member is in the dose setting position, the drive element is further adapted to be placed in the second axial position when the dose setting member is in the dose injection position, the drive means is adapted to trigger energy stored in the energy store when the drive member is in its second axial position.

[0015] The drive element may be adapted to rotate the corresponding piston rod after the energy stored in the energy store has been released. However, in its first position, the drive element is not rotatable because the drive element engages at least part of the housing of the injection device. The injection device may further comprise a spring element, such as a straight spring, for pressing the drive element towards the dose setting element. The straight spring connects actively to the drive element and housing.

[0016] The dose setting element may be adapted to be moved in the longitudinal direction of the injection device so as to move the drive element between the first and second positions. The drive element may be adapted to move from the first to the second axial position by applying force to the dose setting element, force being applied in the axial direction of the injection device. The injection device may, as already mentioned, further include a button disposed in the axis of the dose setting member the push button is adapted to engage the dose setting member when the dose setting member is in the dose setting position and to disengage from the dose setting element when the dose setting member is in the dose injection position. Disconnecting means that the button and the dose setting element can be rotated relative to each other when this disconnected state is reached. The injection device may further comprise a spring element, such as a straight spring, axially pushing the button in a direction of movement away from the drive element.

[0018] The hand-held injection device may further comprise a rotatably mounted indicator element adapted to indicate the dose to be injected from the injection device according to the setting of the dose setting member, the rotatably mounted indicator element may be rotated by an angle corresponding to at least one rotation of the indicator element. The indicator element may comprise an elevator drum having He / bY placed along a substantially helical path on the outer surface. Alternatively or additionally, the indicator element may comprise a counting device having two or more indicator wheels having numbers arranged on the outer surface.

[0019] The hand-held injection device may further comprise a corresponding piston rod which has a threaded outer surface with a drive path arranged in the longitudinal direction of the outer surface of the piston rod. The drive element may be operatively connected to the dose setting element via a pawl.

[0020] The energy store may be disposed between the housing and the dose setting element such that when the dose setting member is rotated, energy is accumulated in the energy store. The energy store may comprise a torsion spring formed as a coil spring, passing coaxially with a corresponding piston rod.

[0021] It should be noted that the interaction between the drive element, the piston rod and the housing can be implemented in various ways. Above, the piston rod has a threaded outer surface and a drive path extending along the piston rod . The wedge arranged on the drive element connects to the driving rod of the piston rod and the forward movement of the piston rod relative to the housing is caused by the threaded outer piston rod which engages with a corresponding threaded housing part. Alternatively, the threaded outer surface of the piston rod may engage with a corresponding threaded portion of the drive member, while the drive path is organized along a piston rod connected to a wedge fixed to the housing.

Brief Description of the Drawing [0022] The invention will now be explained in more detail with reference to the attached figures on which

Fig. 1 shows an injection device according to the invention, wherein the trigger button, located on the upper surface of the device, is actuated by the user's thumb,

Fig. 2 shows an injection device according to the invention, wherein the trigger button is placed on the upper surface of the device and is actuated by the user's forefinger,

Fig. 3 shows an injection device according to the invention, wherein the trigger button is disposed on the upper surface of the dose setting element and wherein the actuator is in the locked position (rotation position of the dose setting element),

Fig. 4 shows an injection device according to the invention, wherein the trigger button is disposed on the upper surface of the dose setting member and wherein the drive member is in the released position (dosing position of the dose setting member),

Fig. 5 is a view showing the drive element in the released position,

Fig. 6 shows a view showing the firing member in the locked position, with the dose setting element,

Fig. 7 is a view showing the trigger in the released position with the dose setting element,

Fig. 8 is a view showing the trigger in a further triggered position, where the dose setting member can rotate,

Fig. 9 illustrates one method of implementing a release mechanism for triggering an energized energy reservoir,

Fig. 10 illustrates another method of implementing a release mechanism for triggering an energized energy reservoir,

Fig. 11 shows a third method of implementing a release mechanism for triggering an energized energy reservoir,

Fig. 12 shows a fourth method for implementing a release mechanism for triggering an energized energy store, and

Fig. 13 illustrates a fifth method of implementing a release mechanism for triggering an energized energy store.

[0023] Although the invention is susceptible to various modifications and alternative forms, particular embodiments are shown, for example, in the drawings and will be described in detail herein. It should be understood, however, that the purpose of the invention will not be limited to the specific forms disclosed. The invention is intended to cover all modifications, equivalents and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

Detailed Description of the Invention [0024] Figs. 1 and 2 show the invention in its most general aspect. 1, a manual injection device 1 is shown. The injection device has an injection needle 2 attached to one of its ends, while the trigger button 3 is located at the opposite end of the injection device. When the trigger button 3 is actuated by applying a force to it in the axial direction of the device, energy is released from the internal energy reservoir, injecting the set dose of the medicament from the injection device. In Fig. 1 the trigger button is actuated by the user's thumb 4, whereas in Fig. 2 the trigger button is actuated by the user's index finger.

[0025] The medicament to be injected is contained in a medicament reservoir, usually shaped as a cylindrical ampoule.

[0026] The energy released by pressing the trigger button 3 is mechanical energy. The energy store may be a spring element, such as a torsion spring. The spring element, when it is released, is adapted to squeeze the set dose of medicament from the medicament container through the injection needle. The trigger button is actively connected to a kind of trigger mechanism, adapted to trigger the spring element when the trigger button is triggered.

[0027] Fig. 3 is a cross-sectional view of one embodiment of the invention. The injection device shown in Fig. 3 includes a housing 6, a dose setting element 7, a drive element 8, a piston rod 9, a torsion spring 10, a compression spring 11, a cylindrical ampoule 12 and a firing element 13. Fig. 3 shows an injection device when an element dose setting is in the dose setting position.

[0028] The dose is set by rotating the dose setting element 7 by a certain angle or a certain number of revolutions. By rotating the dose setting element 7, the torsion spring 10 is stressed because the two ends of the torsion spring 10 are attached to the housing 6 and to the dose setting element 7. The dose setting element 7 is actively connected to the drive element 8 via a catch (not shown). This pawl prevents the dose setting member 7 from returning to the initial position after the torsional spring has been tensioned 10. Since the drive element 8 connects to the housing 6 by a key-operated or keyed connection, the drive element 8 can not rotate with respect to the housing 6 as long as the element the dose setting is in the dose setting position as shown in Fig. 3. In order to maintain the dose setting element 7 and the drive element 8 in the dose setting position, the drive element 8 and the dose setting element 7 are pressed towards the upper end of the injection device. This pressing is provided by a spring element, such as a straight spring 11, arranged between the drive element 8 and the housing part 6. Thus, in order to release the drive element 8 from the connection to the housing 6, a force must be exerted to move the dose setting element 7 and the drive element 8 towards the drug ampoule 12. The cavity 14 allows this movement of the dose setting element 7 and the drive element 8 to be carried forward. Similarly, since the drive element 7 and the piston rod 9 are connected by a wedge-and-groove connection, the drive element 8 can slide axially with respect to the piston rod 9.

[0029] The drive element 8 is released from the connection with the housing 6 in figure 4. In order to achieve this release, the force indicated by the arrow 15 is applied to the firing element 13 such that the firing element 13, the dose element 7 and the drive element 8 are moved at some distance towards the drug ampoule 12. The force indicated by the arrow 15 would normally be exerted by the thumb or forefinger of the user.

[0030] As can be seen in FIG. 4, the engagement region 16 of the housing is now separated from the engagement area 17 of the drive element 8. This disconnection allows the energy of the tautened torsion spring 10 to be released into the dose setting element 7. The dose setting element 7 and the drive element 8 are permanently connected via an intermediate latch (not shown). Thus, once a connection is established between the engagement areas 16 and 17, the dose setting element 7 and the drive element 9 will rotate until the torsion spring 10 has reached the expanded state. Since the drive element 8 and the piston rod 9 are connected by a wedge-and-groove connection, the rotation of the dose setting element 7 and the drive element 8 will also cause the piston rod 9 to rotate. The piston rod 9 has a threaded outer surface,

[0031] Thus, the force exerted on the trigger element 13 will release the energy stored in the torsion spring. This energy is converted into a translational movement of the piston rod in the direction of the ampoule so that the set dose of the drug can be injected from the injection device.

[0032] Fig. 5 is an illustration of a half cut housing 6 of an injection device. As can be seen, the drive element 8 has an area / engaging portion 17 shaped as a gear. Similarly, the housing 6 includes a corresponding area / portion 16 adapted to receive and engage the gear teeth 17.

[0033] Fig. 6 shows another embodiment of the invention. In contrast to the embodiment shown in Figs. 3-5, the embodiment shown in Fig. 6 does not include rotatable portions or external elements. All revolving parts or elements are housed inside the housing 19. Fig. 6 shows a trigger element 20 (formed as a button) which is mechanically pressed towards the end of the injection device by a spring element 22. The trigger element and the dose setting element 21 are pressed into meshing thus as long as the dose setting element 21 is in the dose setting position. The dose setting element 21 is mechanically pressed towards the same end of the injection device as the challenge element 20, thanks to the spring element (shown as spring element 11 in FIG. 3) acting on the drive element (shown as the drive element 8 in Fig. 3), which in turn acts on the dose setting element 21. As can be seen in FIG. 6, the dose setting element 21 is pressed against the mechanical resistance 24, where the protrusion on the dose setting element 21 rests against the housing part 19.

[0034] An intermediate state is shown in Fig. 7. Here, the trigger element 20 has been moved along the axis to a distance sufficient to trigger the firing member 20 from the dose setting element 21. Note that the attachment areas 25 and 26 are disconnected, but because the projection of the dose setting element still abuts against the housing part, no axial movement of the dose setting element 21 occurs at this stage. Thus, the dose setting element 21 can not rotate because the drive element (not shown) is still connected to the housing.

[0035] In Fig. 8, the dose setting element 21 has been moved axially towards the ampoule (not shown) so that the dose setting member can rotate freely, making the piston 27 push the set dose of the ampoule (not shown). Note that in Figure 8 the trigger element 20 and the dose setting element 21 are disconnected. This means that the trigger element 20 does not rotate relative to the housing during the injection of the set dose. Then, when the set dose has been injected, the user removes the thumb or index finger from the trigger, so that the trigger and dose setting element return to their respective positions as shown in Fig. 6, but now the spring element 23 is in the expanded state.

[0036] In the event that the user wants to set a new dose, the user rotates the trigger element that is connected to the dose setting element so that it can set a new dose. Injecting the set dose is obtained according to the steps shown in Figures 7 and 8.

[0037] Figs. 9 - 13 show different embodiments of triggering mechanisms for triggering an energized energy store.

[0038] In Fig. 9, a torsion spring (not shown) is excited by turning the catch 28 which is operatively connected to the housing 30 of the injection device when the dose to be injected is set. In the dose setting position, the pawl 28 is operatively connected to the housing part 31 via the pawl arm 32. The energy stored in the torsion spring is triggered by moving the pawl 28 axially so that it is released from the connection with the housing part 31, because the pawl arm 32 is moved to parts of the housing 33 such that the piston rod 34 can rotate extruding a set dose of medicament.

[0039] In the embodiment shown in Figure 9, the dose indicator drum (not shown) moves in a direction away from the button (not shown) when setting the dose. Of course, the dose indicator drum can be adapted to move in the opposite direction while setting the dose, i.e. towards the button.

[0040] In the embodiment shown in Fig. 10, the latch 35 only cooperates directly with the housing 39. The drive element of the embodiment shown in Fig. 10 consists of three parts, one part 36 is adapted to cooperate with the housing 39, another part 38 is adapted to drive the piston rod 40, an elastic element

37 connects the parts 36 and 38. The elastic member 37 is elastic in the axial direction, but maintains a substantially rigid connection between the parts 36 and 38 when these parts rotate relative to each other. Thus, the elastic element 37 ensures that the parts 36 and 38 can not rotate relative to each other. Thus, when the latch 35 is moved towards the tip of the needle of the injection device, the portion 36 is detached from the housing 39, so that the parts 36, 37 and 38 can rotate the rod 40. The rotational piston 40 causes the prescribed dose of medicament to be extruded from the device injection.

[0041] The embodiment shown in Fig. 11 is similar to the embodiment of Fig. 9, with the exception that the piston rod is moved forwards on drive tracks placed in the housing (instead of in the drive element) and the connection is threaded in between the piston rod and the drive element (instead of a threaded connection between the piston rod and the housing).

[0042] Figs. 12 and 13 show other release mechanisms between the pawl, drive element and housing.