INJECTION DEVICE WITH PRξ-ACTIVATION MEANS

TECHNICAL AREA

The present invention relates to an injection device and in particular to an injection device capable of dispensing a number of preset doses of medicament.

TECHNICAL BACKGROUND

Injection devices that are capable of dispensing certain amounts of medicament are becoming more and more popular. In particular, there is an increased demand for injection devices that are capable of delivering a number of doses before the medicament compartment or container e.g. a cartridge, a syringe, or the like is empty.

Many of the injection devices that have been developed for providing a number of subsequent doses are arranged with some kind of adjustment means which, when handled, sets a certain dose to be delivered. In order to set a dose, the user handles the injector while looking at indications telling the size of the set dose. The user must thus always know the size of the dose to be delivered. Further there is a risk that the user by accident sets a wrong dose and has to reset the dose setting mechanism of the injector and then repeat setting the proper dose.

Further, many patients do not need doses of different size, but rather require the same dose size repeatedly. In those cases it is a drawback to have injectors that can set different dose sizes, when it would suffice with one preset dose.

Thus, there is room for improvement and development of injectors capable of providing a number of subsequent doses of medicament.

BRIEF DESCRIPTION OF THE INVENTION

The aim of the present invention is to remedy the drawbacks with the state of the art injectors. This aim is obtained by an injection device comprising the features of the independent claim. Preferable embodiments of the present invention are the subject of the dependent patent claims.

According to a main aspect of the present invention it is characterised by an injection device for delivering preset doses of medicament, comprising: a front housing and a rear housing; a medicament container disposed within the front housing, wherein the container has a front opening with or for an injection needle for delivering the medicament therethrough and a movable stopper therein; medicament delivery drive means comprising a threaded plunger rod having its front end in contact with said movable stopper, a rotatable drive member rotatably locked to said plunger rod, and preset dose surfaces arranged on the circumference of said rotatable drive member; activation means operably connected to said medicament delivery drive means; and a manually operable pre-activation means operably connected to said activation means, and arranged to be movable between an inactivated position and an activated position; wherein said activation means are arranged to be movable between an idle position in which said activation means are completely arranged within said rear housing and an engaged position in which a rear part of said activation means protrudes from said rear housing when said manually operable pre- activation means is activated from its inactivated position to its activated position for indicating that the injector is armed, and wherein said activation means are also arranged to be movable between its engaged position and its idle position for activating said medicament delivery drive means.

According to another aspect of the present invention, said preset dose surfaces comprises a predetermined number of degrees to each other

corresponding to a predetermined amount of medicament to be delivered

According to a further aspect of the present invention, said medicament delivery drive means further comprises priming surfaces arranged on the circumference of said rotatable drive member, and wherein said priming surfaces comprises a predetermined number of degrees between each preset dose surface and each priming surface corresponding to a predetermined amount of medicament to be primed.

According to yet an aspect of the present invention, said medicament delivery drive means comprises a spring force means acting on said drive member and wherein said manually operable pre-activation means is operably connected to said drive member through a locking mechanism, such that when said manually operable pre-activation means is moved between its inactivated position and its activated position said spring force means is tensioned and held tensioned.

The advantages with the present invention are several. The injector is very easy to use because of the simple handling of the manually operable pre-activation means and that the pop-up button only becomes active when a preset dose has been set.

The user thus obtains an indication that the injector is ready to use because the pop-up button is protruded and could in this respect have an alternative colour that indicates that the injector is ready for injection.

Further, because the manually operable pre-activation means only is capable of being turned or moved a certain preset distance, the user cannot set a wrong dose; he or she simply turns the manually operable pre-activation means until it cannot be moved any further. There is

thus no need for indications or scales that the user has to look at when setting the dose.

Another advantage with the present invention is the preferable use of a torsion spring, preferably helical, that is tensioned when the manually operable pre-activation means is turned. This provides a compact solution with few components in that the handling of the functions of the device is done by turning or rotating components of the device.

These and other aspects of and advantages with the present invention will become apparent from the following detailed description and from the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the following detailed description of the invention, reference will be made to the accompanying drawings, of which

Fig. 1 is a perspective view of an injector according to the present invention, Fig. 2 is a perspective view of the injector of Fig. 1 with a protective cap removed,

Fig. 3 is an exploded view of a first embodiment,

Fig. 4 is a cross-sectional view of the first embodiment,

Fig. 5 is a perspective view of manually operable pre-activation means comprised in the first embodiment,

Fig. 6 is a cross-sectional view of a second embodiment when the injector has its activation means in an idle position,

Fig. 7 is a cross-sectional view of a second embodiment when the injector has its activation means in an engaged position,

Fig. 8 is a perspective view of the inner surface of the rear housing comprised in the second embodiment,

Fig. 9 is a perspective view of a component of the activation means comprised in the second embodiment,

Fig. 10 is a perspective view of a component of the medicament delivery drive means comprised in the second embodiment,

Figs. 1 1a and l ib are perspective views of a component of the activation means comprised in the second embodiment.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to an injection device for delivering preset doses of medicament, comprising: a front housing 10 and a rear housing 12; a medicament container 16 disposed within the front housing, wherein the container has a front opening with or for an injection needle for delivering the medicament therethrough and a movable stopper therein; medicament delivery drive means comprising a threaded plunger rod 18 having its front end in contact with said movable stopper, a rotatable drive member 28 rotatably locked to said plunger rod, and preset dose surfaces 34 arranged on the circumference of said rotatable drive member; activation means operably connected to said medicament delivery drive means; and a manually operable pre- activation means 44 operably connected to said activation means, and arranged to be movable between an inactivated position and an activated position; wherein said activation means are arranged to be movable between an idle position in which said activation means are completely arranged within said rear housing and an engaged position

in which a rear part of said activation means protrudes from said rear housing when said manually operable pre-activation means is activated from its inactivated position to its activated position for indicating that the injector is armed, and wherein said activation means are also arranged to be movable between its engaged position and its idle position for activating said medicament delivery drive means.

Both housings 10, 12 are of elongated shapes, forming a pen-like injector. The front housing is further arranged with a protective cover 14 when the injector is not used.

In the first embodiment shown in Fig. 3 and Fig. 4, the threaded plunger rod 18 is threaded into a threaded passage of a nut 22. The outer surface of the nut is arranged with splines 24, which mate with corresponding splines on the inner surface of the rear housing. The nut is further in contact with a wall 26 of the rear housing. Against the wall a rotatable drive member 28 is arranged. The rotatable drive member 28 is elongated rod-like having an inner passage, which houses the plunger rod. The plunger rod is arranged with an elongated groove 30, which mates with corresponding protrusions (not shown) in the passage, whereby the plunger rod is rotatably fixed in relation to the dose wheel, but axially movable. The front part of the rotatable drive member 28 is arranged with the preset dose surfaces 34 which comprise a predetermined number of degrees to each other corresponding to a predetermined amount of medicament to be delivered. Said medicament delivery drive means further comprises priming surfaces 36 arranged on the circumference of said rotatable drive member, and wherein said priming surfaces comprises a predetermined number of degrees between each preset dose surface and each priming surface corresponding to a predetermined amount of medicament to be primed. Said dose surfaces are determined during the manufacturing of the device.

Said medicament delivery drive means further comprises a spring force means 38 acting on said rotatable drive member 28, in the embodiment shown in Fig. 3 and Fig. 4, a helical torsion spring. A front pin 40 of the spring is placed in a fixation hole provided in a circumferential ledge of the rotatable drive member. A rear pin 42 of the spring is placed in a fixation hole in a circumferential ledge of the manually operable pre- activation means 44.

The manually operable pre-activation means 44 has a sleeve-like rear part 46 provided with a circumferential protrusion 48 that fits onto a circumferential groove 50 of the rear housing such that the sleeve-like part 46 may be turned in relation to the rear housing. The manually operable pre-activation means 44 is further arranged with a tubular part 52 extending around the drive member, and wherein the rear end surface has a pointed shape which cooperates with a recess in an end wall of the manually operable pre-activation means, the function of which is to reduce friction between the drive member and the manually operable pre-activation means 44.

The activation means comprises a sleeve 54 and a rotating member 64 which are connected together in such a form that the rotating member 64 is rotatable in relation to said sleeve 54. The sleeve 54 partially surrounds the rotatable drive member 28 and the drive spring. At the front end of the sleeve 54, on the inner walls, a number of inwardly directed protrusions 56 are attached, which protrusions cooperate with the preset dose surfaces 34 and/ or the priming surfaces 36 in a manner that will be described hereinbelow. The rear part of the sleeve 54 is arranged with a number of flexible arms 58 arranged with inwardly directed ledges 60. These ledges cooperate with an outwardly directed circumferential ledge 62 that is attached to the front end of the rotating member 64, hereafter named rotator.

The outer surface of the rotator is provided with a groove 66 that runs along its circumference. The groove has a certain shape with a repeated pattern, comprising a straight part 66a directed in the longitudinal direction of the device and an inclined part 66b. The groove 66 cooperates with a fixed guide 67 arranged on the inner surface of the rear housing in a manner that will be described below. The upper part of the rotator is provided with two opposite cut-outs, whereby two arms 68 are formed. The arms extend through passages in the manually operable pre-activation means 44 such that the rotator is rotationally locked to said manually operable pre-activation means 44 but axially slidable. The arms are arranged with holes 70, into which inwardly extending protrusions of a pop-up button 72 are placed. The pop-up button provided with a circumferential protrusion that fits completely into a circumferential groove of the sleeve-like rear part 46 such that the pop-up button may be longitudinally displaced in relation to the housing.

The manually operable pre-activation means 44 is operably connected to said drive member 28 through a locking mechanism, such that when said manually operable pre-activation means is moved between its inactivated position and its activated position said spring force means is tensioned and held tensioned. The locking mechanism comprises a ring 90 with at least one ridge or ledge arranged on mating ridges or ledges on the tubular part 52 of the manually operable pre-activation means, and a spring 74 arranged between said ring 90 and a circumferential elevation 92 the tubular part 52 of the manually operable pre-activation means. The ring 90 is arranged with at least one bevelled protrusion 91 arranged to be in contact with one of a number of equally distributed bevelled recesses (not shown) arranged on said drive member 28, such that when said manually operable pre-activation means 44 is moved between its inactivated position and its activated position, said at least

one bevelled protrusion 91 is moved along said equally distributed bevelled recesses arranged on said drive member 28.

The device is intended to function as follows. When the device is delivered to the intended user, as shown in Fig. 1 , the protective cover is removed, an injection needle is attached. The activation means is in its idle position when the inwardly directed protrusions 56 of the sleeve 54 are disposed in contact with the preset dose surfaces 34. The activation means are moved from its idle position to its engaged position when the manually operable pre-activation means 44 is turned in relation to the rear housing 12. Because the rotator and the pop-up button are rotatably connected to the manually operable pre-activation means 44, the rotator will also rotate. This causes the fixed guide 67 of the housing to move along the groove 66 of the rotator. Because of the inclined part of the groove that the fixed guide moves in, the rotator and pop-up button is forced towards protruding somewhat out from the rear housing. The movement of the rotator causes the sleeve 54 to be moved linearly toward the rear end of the injector wherein the protrusions 56 of the sleeve 54 comes out of contact with the preset dose surfaces 34 allowing the drive member 28 to rotate somewhat until the protrusions 56 comes into contact with the priming surfaces 36. The short rotational displacement of drive member 28 forces the plunger rod to move longitudinally towards the front end of the injector, pressing the stopper for priming the container.

Since the protrusions 56 of the sleeve 54 are in contact with the priming surfaces 36, the drive member is held in a fixed rotational position when continuing the turning of the manually operable pre- activation means 44 and allows the torsion spring 38 to be tensioned because of its attachment between drive member 28 and the manually operable pre-activation means 44. At the same time the least one bevelled protrusion 91 of the ring 90 is resiliently moved along said

equally distributed bevelled recesses arranged on the drive member 28 whereby the drive member 28 is rotationally locked and the torsion spring 38 is held a tensioned state. When the manually operable pre- activation means 44 and the rotator have been turned a certain amount, the protrusions 67 leave the inclined part 66b of the groove and reaches the vertical part 66a.

The injector is then primed, armed and ready to use, and the activation means is in its engaged position which is indicated by the pop-up button now protruding outside the rear housing of the injector, Fig. 2. In order to further enhance the indication, the side surface of the popup button may be of another colour, perhaps also bright, indicating that the injector is armed.

The skin is now penetrated by the needle at the injection site. When the penetration is completed, the activation means are movable between its engaged position and its idle position for activating said medicament delivery drive means by pressing the pop-up button into the circumferential groove of the sleeve-like rear part 46. This causes the vertical part 66a of the groove to be displaced on the fixed guide 67 of the housing. The sleeve 54 moves also vertically towards the front of the injector. This causes the protrusions 56 of the sleeve 54 to move out of contact of the priming surfaces 36, whereby the drive member 28 is free to rotate due to the force of the torsion spring 38. The rotation of the drive member causes the plunger rod to rotate due to the rotational locking between them. Due to the rotation of the plunger rod it will move forward acting on the stopper, due to the thread of the nut 24 cooperating with the thread of the plunger rod. Thus, medicament is expelled through the needle due to the movement of the stopper. The injection is completed when the dose wheel has rotated such that the protrusions 56 of the sleeve 54 come into contact with the preset dose surfaces 34. The pop-up button is held in the interior of the circumferential groove of the sleeve-like rear part 46 by the rotator 64

until said manually operable pre-activation means 44 is turned again for delivering a new preset dose.

When the injection is completed, the needle is manually withdrawn from the injection site. The protective cover 14 can now be reattached, possibly after the used needle has been discarded and a new sterile needle is mounted. Thus the injector is ready for a subsequent injection. The injector is thus used a number of times according to the above description until the container is emptied. The injector may now be disassembled and a new container be introduced. In order to "reset" the injector, the nut 24 with the plunger rod 18 is removed from the injector and the plunger rod is threaded back to its original position. The nut and the plunger rod are then mounted back in the injector. In this context it is to be understood that other solutions regarding resetting of the device are possible. For example the nut 24 may be arranged with teeth on its rear surface co-acting with corresponding teeth on the forwardly facing surface of the fixed wall 26. A resilient means, e.g. a spring, is further arranged between the nut and the wall. When the container holder with the container is screwed onto the housing, the teeth of the nut engage the teeth of the wall, against the force of the spring. Thus the nut is locked from rotating. When an empty container is to be replaced with a full container, the container holder is removed. This releases the nut and it is pushed out of contact with the wall due to the spring. The plunger rode may now easily be brought back to its original position and the device loaded with a new container.

In a second embodiment, the injector comprises a front housing 1 10 and a rear housing 1 12; a medicament container disposed within the front housing, wherein the container has a front opening with or for an injection needle for delivering the medicament therethrough and a movable stopper therein; medicament delivery drive means comprising a threaded plunger rod 146 having its front end in contact with said

movable stopper, a rotatable drive member 148 rotatably locked to said plunger rod, and preset dose surfaces 156 arranged on the circumference of said rotatable drive member; activation means operably connected to said medicament delivery drive means and a manually operable pre-activation means operably connected to said activation means, and arranged to be movable between an inactivated position and an activated position; wherein said activation means are arranged to be movable between an idle position in which said activation means are completely arranged within said rear housing and an engaged position in which a rear part of said activation means protrudes from said rear housing when said manually operable pre- activation means is activated from its inactivated position to its activated position for indicating that the injector is armed, and wherein said activation means are also arranged to be movable between its engaged position and its idle position for activating said medicament delivery drive means, see Figs. 6 and 7 .

The rear housing is further arranged with a central passage arranged with threads 144 and ramps 152 through which the threaded plunger rod 146 is arranged, Fig, 8. The drive member 148 is arranged adjacent the threaded passage. The plunger rod extends through the drive member in a rotationally locked, but slidable manner with the help of a spline design. The front end surface of the drive member is arranged with a ratchet interface having inclined ramps 150 co-acting with a surface surrounding the central passage with corresponding ramps 152 of the rear housing, the function of which will be described below. A rear end of the drive member has a somewhat larger diameter and is arranged with a number of outwardly preset dose surfaces 156 on its circumference which comprise a predetermined number of degrees to each other corresponding to a predetermined amount of medicament to be delivered and where the preset dose surfaces have somewhat inclined surfaces 158, Figs. 9 and 10. In the shown second embodiment

there are three preset dose surfaces arranged 120° to each other around the circumference.

The activation means comprises a thumb button 1 14 and toggle sleeve 160 operably connected to each other and wherein the toggle sleeve is arranged to co-act with the drive member 148. The front end of the toggle sleeve is arranged with a circumferential ledge 162 having a number of cut-outs 164, which mate with longitudinal ridges 166 on the inner surface of the rear housing, Fig. 1 Ia. At the inner walls of the toggle sleeve inclined ridges 168 are arranged, Fig. l ib, which cooperate with the inclined surfaces 158 of the preset dose surfaces 156 in a manner that will be explained. The rear end surface 170 of the toggle sleeve 160 is arranged with inclined surfaces 172, Fig. 1 1a, which surfaces co-act with corresponding surfaces 176 of a tubular part 178 of the thumb button 1 14. The front end surface of the thumb button is arranged with a number of inclined surfaces 188 and stop ledges 190. Finally a resilient means 192, e.g. a spring, is arranged between an inner surface of the thumb button and the rear end of the drive member, Fig. 7.

The manually operable pre-activation means comprises a prolonged part of the rear housing and a locking mechanism (not shown), e.g. a flexible ring, a flexible land or the like, operably connected to the prolonged part of the rear housing and to the thumb button 1 14, such that when said manually operable pre-activation means is in an inactivated position said locking mechanism is engaged with said thumb button holding said thumb button within the rear housing and when said manually operable pre-activation means is in an activated position said locking mechanism is released from said thumb button such that said thumb button protrudes somewhat from the rear housing.

The device is intended to function as follows. When the device is delivered to the user, an end cover is removed by pulling it off the injector. The manually operable pre-activation means is moved from its inactivated position to its activated position such that the thumb button protrudes somewhat from the rear housing. The force from the resilient means 192 will force the activation means from its idle position to its engaged position by forcing the toggle sleeve towards the rear end of the injector and allowing the toggle sleeve to slightly rotate due to the ramps 172 on the rear end of the toggle sleeve working with the mating ramps 176 on the thumb button such that the inclined ridges 168 of the toggle sleeve are in position to act on the preset dose surfaces 156 of the drive member. The activation means is then in its engaged position which is indicated by the thumb button now protruding outside the rear housing of the injector. In order to further enhance the indication, the side surface of the thumb button may be of another colour, perhaps also bright, indicating that the injector is armed. The skin is now penetrated by the needle at the injection site. When the penetration is completed, the activation means are movable between its engaged position and its idle position for activating said medicament delivery drive means by pressing the thumb button which causes the toggle sleeve 160 to move forward. This in turn will cause the drive member 148 to rotate because of the inclined ridges 68 of the toggle sleeve acting on the end surfaces 158 of the preset dose surfaces 156 of the drive member. The rotation of the drive member is transmitted to the plunger rod 146 because of the rotational lock between them, and due to the threads of the plunger rod cooperating with the threads of the rear housing; the plunger rod will move forward and thus press the stopper towards the front end of the device.

When the drive member has rotated about 120° the ratchet interface between the drive member and the rear housing is such that the ramps 150, 152 falls into the next indexed position and the preset dose is

completed. The ramps providing the indexed positions prevent any backdriving of the drive member. The locking mechanism of the manually operable pre-activation means hold the thumb button in within the rear housing until it is released for a subsequent injection.

When the injection is completed, the needle is manually withdrawn from the injection site. The protective cover can now be reattached, possibly after the used needle has been discarded and a new sterile needle is mounted. Thus the injector is ready for a subsequent injection. The injector is thus used a number of times according to the above description until the container is emptied. The injector may now be disassembled and a new container be introduced.

It is to be understood that the embodiment described above and shown in the drawings is to be regarded only as a non-limiting example of the invention and that it may be modified in many ways within the scope of the patent claims.