Abstract:
The present invention relates to a medicament delivery device that is reliable, safe and intuitive to use and configured to prevent a subsequent does from being administered before a previously initialized dose has been fully delivered. This is accomplished by mechanically interacting structures arranged as an interface between a lockable delivery button and a release member.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a medicament delivery device for delivering medicament and in particular to a medicament delivery device where safety and handling aspects have been improved by the interaction of a lockable injection button and a release button. 
       BACKGROUND 
       [0002]    Basically a medicament delivery device is a device that is simple to use without the need of performing many steps when an individual has to administer a dose of medicament by himself/herself. This requires a solution able of keeping a medicament delivery device as pre-assembled and ready as possible, in order to deliver the medicament in a measured dosage, without many manual operations or actions. Thus, to minimize the number of steps needed, in order to perform a medicament delivery, some known prior art devices only need to be actuated against the delivery area, without the need of manual actuation, by pressing a button or the like, which causes the medicament delivery device to perform the delivery. There is however a common request for a medicament delivery device which is very easy to use and which can reliably deliver a set dose of a medicament in a safe way. 
         [0003]    U.S. Pat. No. 5,925,021 discloses a pen injector device comprising a locking means for locking the actuator knob in a depressed position, a start button for releasing the actuator button and a dosage knob for setting a prescribed dose. U.S. Pat. No. 5,925,021 also comprises electronics, such as sensors and display devices for controlling the injection, for measuring and storing ejected doses and for displaying information to the user. A disadvantage of this prior art is that a dose needs to be set and then injected manually by pushing the actuator button until it stops. In a stressful situation, or if handled by an inexperienced user, the injection may be interrupted mid-way and the button may be released inadvertently. If the button is depressed again, i.e. without adjusting the dosage, a new dose of the previous setting will be initialized, which will lead to the patient receiving an overdose. 
         [0004]    There is therefore a need for an arrangement that can provide safe and simple handling both by inexperienced users and in stressful situations. Hence, there is a need for an arrangement where a predetermined dosage is fully delivered, i.e. an arrangement for administering a predetermined dose such that the delivery of a previously initialized dose of medicament has to be fully completed before delivery a subsequent predetermined dose can be initialized. Thus, as can be noted, human handling aspects of the medicament delivery device are crucial and there are several rationales for improving existing solutions. 
       SUMMARY 
       [0005]    An object of the embodiments of the present invention is to provide a medicament delivery device that is reliable, safe and intuitive to use and that does not allow a subsequent dose to be administered before a previously initialized dose has been fully delivered. This is achieved by the main aspect of the invention, wherein a delivery device for delivering predetermined amounts of medicament, comprises a body having an outer housing and an inner housing and having a proximal and an opposite distal end, a cartridge with medicament to be delivered arranged inside said inner housing, said cartridge comprising an opening for expelling said medicament and a stopper movable inside said container, a threaded plunger rod arranged movable inside said body in the longitudinal direction and in contact with said movable stopper, a manually operated push means movable in the longitudinal direction and capable of, upon operation, moving said plunger rod towards said movable stopper, thereby expelling medicament through said opening, and a spring means for biasing said push means towards the distal end of the device, and a first driver and a second driver for transforming a generally linear movement of said push means to a rotational movement of said plunger rod, wherein said transforming means comprises a first set of protruding structures arranged on said first driver cooperating with a set of inclined ledges arranged on said second driver rotatably locked to said plunger rod, wherein in the device comprises a movable release member having a guide member adapted to interact with a guide frame arranged on the outer circumferential surface of the manually operated push means and wherein said guide frame is configured to prevent the delivery of a subsequent dose before a previously initialized dose has been fully administered. 
         [0006]    According to a further aspect of the invention the guide frame comprises parallel first and second longitudinally oriented tracks separated by a longitudinally oriented wall element and connected to each other by distal and proximal transversal tracks. 
         [0007]    According to a further aspect of the invention the guide member is arranged to project into said tracks. 
         [0008]    According to a further aspect of the invention said manually operated push means, in cooperation with said release member, is movably arranged in the longitudinal direction between a depressed position in which the guide member is generally aligned with said distal transversal track and a released position in which the guide member is generally aligned with said proximal transversal track. 
         [0009]    According to a further aspect of the invention the release member, in cooperation with said push means, is arranged movable along a transversal direction between a first position in which the guide member is generally aligned with said first track and a second position in which the guide member is generally aligned with said second track. 
         [0010]    According to a further aspect of the invention said release member comprises a resilient element and wherein said resilient element is arranged to bias said release member in the transversal direction towards said first position. 
         [0011]    According to a further aspect of the invention said distal transversal track comprises a longitudinally aligned ramp that is capable of interacting with said guide member to allow movement of said release member from said first position to said second position. 
         [0012]    According to a further aspect of the invention the first longitudinally oriented track is arranged with a first transversally aligned step ramp at a distal end of said wall element and a second transversally aligned step ramp at a proximal end of said wall element, wherein said first and second step ramps are capable of interacting with said guide member to allow movement of said manually operated push means towards the depressed position and to prevent said manually operated push means from return movement towards the released position. 
         [0013]    According to a further aspect of the invention said guide member is arranged on a flexible tongue of the release member. 
         [0014]    By the disclosed medicament delivery device mis-delivery of a dose of medicament is avoided. The delivery of a dose of medicament may be interrupted, but a subsequent dose cannot be administered until a previously initialized dose has been completely delivered. The described advantages are possible due to the fact that it is impossible to reset the manually operated push means, such as an injection button, for a subsequent dose without first depressing it completely to eject the remainder of the current, initialized dose. 
         [0015]    These and other aspects and advantages of the present invention will become apparent from the following detailed description and from the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    In the following description of embodiments of the invention, reference will be made to the accompanying drawings of which: 
           [0017]      FIG. 1  is a perspective view of an exemplary medicament delivery device according to the invention. 
           [0018]      FIG. 2  shows, in perspective, a view inside the medicament delivery device of  FIG. 1  without the outer housing. 
           [0019]      FIG. 3  illustrates, in perspective, an exploded view of the components of the actuating mechanism of the medicament delivery device of  FIG. 1 . 
           [0020]      FIG. 4  illustrates, in perspective, an exploded view of the manually operated push means and the release member of the medicament delivery device of  FIG. 1 . 
           [0021]      FIGS. 5A-5F  illustrates a sequence of the manually operated push means and the release member in different states of operation. 
           [0022]      FIG. 6A  illustrates, in perspective, a second drive member of the medicament delivery device of  FIG. 1 . 
           [0023]      FIG. 6B  illustrates a cross section of  FIG. 6A . 
           [0024]      FIG. 7  illustrates a cross section of the manually operated push means of the medicament delivery device of  FIG. 1 . 
           [0025]      FIGS. 8A-8F  illustrate, in a sequence of transparent views, the cooperation of a second drive member and a first drive member. 
       
    
    
     DETAILED DESCRIPTION 
       [0026]    Embodiments of the present invention will now be described in detail. As should be noted in the present application, when the term “distal part/end” is used, this refers to the part/end of the delivery device, or the parts/ends of the members thereof, which is/are located the furthest away from the medicament delivery site of the patient. Correspondingly, when the term “proximal part/end” is used, this refers to the part/end of the delivery device, or the parts/ends of the members thereof, which, is/are located closest to the medicament delivery site of the patient. 
         [0027]    According to the main aspect of the invention, a medicament delivery device for delivering predetermined amounts of medicament comprises a body having an outer housing and an inner housing, and having a proximal and an opposite distal end, a cartridge with medicament to be delivered arranged inside said inner housing, said cartridge comprising an opening for expelling said medicament and a stopper movable inside said container, a threaded plunger rod arranged movable inside said body in the longitudinal direction and in contact with said movable stopper, a manually operated push means movable in the longitudinal direction and capable of, upon operation, moving said plunger rod towards said movable stopper, thereby expelling medicament through said opening, and a spring means for biasing said push means towards the distal end of the device, and a first driver and a second driver for transforming a generally linear movement of said push means to a rotational movement of said plunger rod, wherein said transforming means comprises a first set of protruding structures arranged on said first driver cooperating with a set of inclined ledges arranged on said second driver rotatably locked to said plunger rod, wherein in the device comprises a movable release member having a guide member adapted to interact with a guide frame arranged on the outer circumferential surface of the manually operated push means and wherein said guide frame is configured to prevent the delivery of a subsequent dose before a previously initialized dose has been fully administered. 
         [0028]    According to a further aspect of the invention the guide frame comprises parallel first and second longitudinally oriented tracks separated by a longitudinally oriented wall element and connected to each other by distal and proximal transversal tracks. 
         [0029]    An exemplary embodiment of the present invention is shown in the  FIGS. 1-8 . The exemplary embodiment shown in the figures is a medicament injector for dual medicament cartridges but is not restricted to it.  FIG. 1  is a perspective view of exemplary components of a complete medicament delivery device  10  according to the invention.  FIG. 1  illustrates the pre-assembled medicament delivery device  10  extending in a longitudinal direction  100 . Some of the components of the device can be movable in a transversal direction  200  which is orthogonal to the longitudinal direction  100 . 
         [0030]    The exemplary delivery device comprises an outer housing  17  arranged with a first view window  11  for indicating the remaining amount of medicament A proximal end of the cartridge container  14  projects from the proximal end of the outer housing  17 . The cartridge container  14  is arranged with a second view window  13  for a user to verify that medicament contents (not shown) have been mixed. The cartridge container  14  is also arranged at its proximal end with engaging means  12  as e.g. threads but not restricted to it, such that a delivery member can be connected. The delivery member may be a needle, a nozzle, a mouth piece, or the like. At the distal part of the outer housing  17  a release member  20  is movably arranged in the transversal direction  200  and a manually operated push means  30 , e.g. a push button, is movably arranged in the longitudinal direction  100 . 
         [0031]      FIG. 2  is a perspective view that illustrates the medicament delivery device  10  without the outer housing  17  ( FIG. 1 ). An inner housing  18  is arranged to receive a distal part of the cartridge container  14  by threaded engagement between the outer distal surface of the cartridge container  14  and an inner surface of the inner housing  18 . Connected to the distal part of the inner housing  18  is a first driver  15 , rotatably arranged but movably locked in a longitudinal direction in relation to the housings  17  and  18 . By a structural interface (not shown) between the inner distal annular surface of the inner housing  18  and a proximal annular surface of the first driver  15 , reverse rotation of the first driver  15  is prevented as the manually operated push means  30  moves towards a released position (to be explained below). The first driver  15  is arranged with outer threads that engage inner threads of an indicator means  16 . Since the indicator means  16  is rotatably locked to the outer housing  17 , rotation of the first driver  15  is transformed into longitudinal movement of the indicator means  16  in relation to the outer housing  17  for indicating the remaining amount of medicament through the first view window  11  ( FIG. 1 ). 
         [0032]    The release member  20 , as shown in  FIG. 2 , may have an annular form and be arranged in close proximity around the manually operated push means  30 . A guide member  21  protrudes radially inwards from the release member  20  to engage a guide frame  31  arranged on the outside circumferential surface of the manually operated push means  30 . The part of the release member  20  that is operated by a patient/user and that protrudes through the outer housing  17 , as shown in  FIG. 1 , may be shaped as a push button. The release member is actuated by a user in order to unlock the device for delivery of a dose of medicament. After actuation, the release member  20  is returned by a resilient member  22  that is arranged in a transversally biased position, abutting the inside of the outer housing  17 . In the exemplary embodiment, the resilient member  22  depicted in  FIG. 2  is in the shape of a flexible finger of the release member, but it could just as well be any other kind of flexible member, e.g. a coil spring. The effect might also be attained by a native resilience of the material and/or the shape of the release member  20  itself The cooperation between the guide member  21  and the guide frame  31  ensures the safe and simple delivery of complete doses of medicament, which will be explained in detail below. 
         [0033]    The general function of the exemplary medicament delivery device, as shown in  FIGS. 1 and 2 , is described by the following steps. The device is operated by first unlocking and releasing the manually operated push means  30  by depressing the release member  20  in the transversal direction and then actuating the push means  30  in the longitudinal direction. A second driver  40  ( FIG. 3 ) is arranged coaxially on the distal part of the first driver  15 . The distal end of the second driver is arranged coaxially within the manually operated push means  30 , acting to transform the longitudinal movement of the push means  30  to rotational movement of the first driver  15 , which mechanism will be explained below. A plunger rod (not shown) is slidably arranged, but rotatably locked inside the first driver  15  and extends from the inside of the first driver  15  to threaded engagement with a threaded opening at a distal annular surface of the inner housing  18 . The proximal end of the plunger rod extends into a cartridge (not shown) which is positioned in the cartridge container  14  and is abutting to a movable stopper (not shown) that acts on medicament within the container to drive it towards the delivery member as the plunger rod is actuated by the rotation of the first driver  15 . Since the plunger rod is rotatably locked to the first driver  15  and since the inner housing  18  is fixed to the outer housing, the relative rotation of the first driver  15  in relation to the inner housing  18 , urges the plunger rod in the longitudinally proximal direction by the threaded engagement between the plunger rod and the inner housing  18 . 
         [0034]    The exemplary embodiment, as shown in  FIG. 3 , is an exploded view of the main components of the invention at the distal end of the medicament delivery device. The first driver  15  is rotatable, but movably locked along a longitudinal axis. A spring means  19  is arranged in permanent compression between an annular ledge on the distal end of the first driver  15  and on an annular inner surface of the distal end of the second driver  40 . The second driver is movable, and to a limited extent rotatable, along the longitudinal axis. The spring means  19  forces the second driver  40  against the inner surface of the distal end of the manually operated push means  30 . The manually operated push means  30  is movable along a longitudinal axis. The release member  20 , which is transversally movable, is arranged coaxially with the push means  30  and aligned with the guide frame  31  for the interaction between the release member  20  and the push means  30 . The operation of the exemplary embodiment of  FIG. 3  will be explained below. 
         [0035]      FIG. 4  shows a perspective view of an exemplary embodiment of the manually operated push means  30  and the release member  20 . In order to obtain a medicament delivery device that is safe and simple to handle in accordance with the invention it is necessary to have the device operate sequentially in steps. Therefore the manually operated push means  30  is arranged with at least one guide frame  31 , such as two guide frames positioned opposite to each other on the circumferential surface of the push means. The release member  20  is arranged with at least one guide member  21 , positioned to cooperate with the at least one guide frame  31 . 
         [0036]    The guide frame  31  comprises a first longitudinally oriented track  33  that runs parallel to a second longitudinally oriented track  34 . They are separated by a longitudinally oriented wall element  32  and connected to each other by a distal transversal track  35  and a proximal transversal track  36 . The term track should be interpreted in its widest sense as a path relative to which the guide member  21  may move in a substantially confined manner, i.e. without deviating from the track. Different solutions to tracks are conceivable. The exemplary embodiment of  FIG. 4  shows a guide frame having walls that protrude radially from the surface of the manually operated push means  30  and wherein the proximal transversal track  36  is open towards the proximal side. Since the guide member  21  is arranged on the release member  20 , which is movably confined transversally by the outer housing  17 , the guide member  21  is still aligned with either of the longitudinal tracks  33 ,  34  even if it should be positioned proximally to the proximal transversal track  36 , i.e. proximally to the guide frame  31  as a whole. 
         [0037]    The distal transversal track  35  comprises a longitudinally aligned ramp  37 . The first longitudinally oriented track  33  comprises a first transversally aligned step ramp  38  at a distal end of the wall element  32  and a second transversally aligned step ramp  39  at a proximal end of the wall element  32 . The purpose of these ramps will be explained in conjunction with  FIGS. 5A-F . 
         [0038]    The guide member  21  may be arranged as a protrusion, e.g. in the form of a step ramp, directed radially inwardly to protrude into the tracks of the guide frame  31  for interaction therewith. Said protrusion being arranged on at least one flexible tongue, or cut-out, on the circumference of the release member  20 . The manually operated push means  30  is movable in the longitudinal direction while the release member  20  is movable in the transversal direction. The manually operated push means  30  is arranged to be movable in the longitudinal direction between a depressed position in which the guide member  21  is generally aligned with said distal transversal track  35  and a released position in which the guide member  21  is generally aligned with said proximal transversal track  36 . The release member  20  is movably arranged in the transversal direction between a first position in which the guide member  21  is generally aligned with said first track  33  and a second position in which the guide member is generally aligned with said second track  34 . 
         [0039]    The manually operated push means  30  is permanently longitudinally biased in the distal, released, direction by the spring means  19  ( FIG. 3 ) and the release member  20  is permanently transversally biased towards the first position by the resilient member  22 . Force is required by the user of the device to displace the release member  20  and the push means  30  against their respective biasing directions. 
         [0040]    Referring now to  FIGS. 5A-F , illustrated is a sequence of steps that show the operation of the medicament delivery device  10  and the interaction between the manually operated push means  30  and the release member  20 . In  FIG. 5A  the medicament delivery device  10  is in a locked position in which the push means  30  is in the depressed position and is locked from movement towards the released position by an engagement between the guide element  21  and the first transversally aligned step ramp  38 . The release member is stable in the first position due to the permanent spring bias of the resilient member  22 . To unlock the medicament delivery device  10 , the user has to displace the release member  20  towards the second position by exerting a transversal force on the release member  20  that overcomes the spring bias of the resilient member  22 . A certain additional frictional force is required to overcome the resistance presented by the longitudinally aligned ramp  37  in order to lower the risk of accidental unlocking of the device. 
         [0041]    Turning to  FIG. 5B , illustrated is a state where the medicament delivery device  10  has been unlocked wherein the release member  20  is still held in the second position by the user after displacement from the first position ( FIG. 5A ). The manually operated push means is biased towards the released, distal, position by the spring means  19 . Consequently the push means  30  is displaced distally towards the released position.  FIG. 5C  shows the push means  30  moving distally towards the released position. 
         [0042]    As illustrated in  FIG. 5D , the push means  30  has reached the released position while the user is still holding the release member  20  in the second position. As he/she lets go of the release member  20 , it is returned to the first position by the bias of the resilient member  22 , as seen in  FIG. 5E . Referring back to the  FIG. 5C , if the user drops the release member  20  while the push means  30  is still moving, the wall element  32  will still hold the guide member  21  and the release member  20  in the second position, thereby preventing return movement of the release member  20  to the first position. When the push means  30  reaches the released position, the guide element  21  aligns with the proximal transversal track  36 , allowing return movement of the release member  20 . 
         [0043]      FIG. 5F  illustrates the push means  30  and the release member  20  after initial depression of the push means  30 . As the push means  30  is proximally depressed as shown in  FIG. 5F , the second transversally aligned step ramp  39  passes the guide member  21 , making an audible clicking sound as the guide member  21  and the second step ramp  39  snap into locking engagement with each other. The only possible movement of the guide member  21  and the push means  30  hereafter is the continued depression of the push means  30 . The purpose of the second step ramp  39 , apart from giving an audible indication to the user, is to prevent the push means  30  from returning to the released position and thereby resetting for a subsequent dose before the current, previously initialized dose has been fully administered. The mechanism for resetting the device is explained in conjunction with  FIGS. 6-8 . When completely depressed, the push means is back at the depressed position, shown in  FIG. 5A . As the first transversally aligned step ramp  38  passes the guide member  21 , an audible sound is made as the guide member  21  and the first step ramp  38  snap into locking engagement with each other, locking the device and also indicating to the user that the dose has been fully delivered. 
         [0044]    Although the main aspects of the invention concern the interaction between the release member  20  and the manually operated push means  30 , as exemplified by FIGS.  4  and  5 A-F, a crucial part of the operation of the medicament delivery device  10  is the interaction between the first driver  15  and the second driver  40 . One such exemplary embodiment is shown in  FIG. 6-8 . 
         [0045]      FIG. 6A  shows a perspective view of the second driver  40 , comprising a protruding, longitudinal rib  41  arranged on the outer circumferential surface. Inclined ramps  42  are arranged on the distal end surface of the second driver  40 .  FIG. 6B  illustrates a cross section of the second driver  40  wherein its inner circumferential surface comprises inside inclined ledges  43  facing generally the proximal direction and return ledges  44  facing generally in the distal direction. 
         [0046]    The inclination of the ledges and number of ledges depend on the amount of medicament to be delivered per dose and are set to predetermined values during manufacturing of the second driver  40 . In the illustrated embodiment in  FIG. 6B , for instance, there are two oppositely arranged inclined ledges  43  that correspond to two protruding structures  50  on the outer circumference of the first driver  15 , exemplified in  FIG. 3 . 
         [0047]      FIG. 7  is a cross section of the manually operated push means  30 . Longitudinal protruding strips  301  ( FIG. 7 ) are arranged on the inside circumferential surface. A seat  302  is arranged on the inner proximally directed surface of the manually operated push means  30   
         [0048]    The operation of the first and second driver is best described by the sequence of drawings illustrated in  FIGS. 8A-F , which is a sequence of transparent views of the second driver  40  and the first driver  15  that correspond to the sequence of  FIGS. 5A-F .  FIG. 8A  represents the locked position of the medicament delivery device  10 , showing the protruding structure  50  of the first driver at the distal end of the inclined ledge  43 . Due to the depressed position of the manually operated push means  30  (not shown) the inclined ramps  42  arranged on the distal end of the second driver are pressed into the seat  302  ( FIG. 7 ) by the force of the spring means  19  (not shown), rotationally locking the second driver  40 . 
         [0049]      FIGS. 8B-C  show that the actuation of the release member  20  towards the second position does not directly affect the drivers ( FIG. 8B ), but as the push means  30  is displaced towards the released position by the spring means  19 , the force of the inclined ramps  42  against the seat  302  is relaxed, allowing the return ledge  44  to slide against the proximal inclined surface  54  of the first driver  15 . This rotates the second driver  40  in relation to the first driver  15  and the push means  30  The rotation is limited by the longitudinal rib  41  of the second driver  40  that is loosely confined between the longitudinally protruding strips  301  ( FIG. 7 ) on the inside circumferential surface of the push means  30 . Reverse rotation of the first driver  15  during this phase is prevented by the interaction of a structural interface, e.g. a kind of ratchet interface, between the inner distal annular surface of the inner housing  18  and a proximal annular surface of the first driver  15  (not shown). 
         [0050]    Referring to  FIG. 8D , as the proximal end of the return ledge  44  slides past the protruding structure  50  and the second driver  40  reaches the released position, the inclined ramps  42  are, again, urged against the seat  302 , making the second driver  40  rotate back in relation to the first driver  15  and the push means  30 , aligning the distal inclined surface  52  with the proximal end of the inclined ledge  43 . 
         [0051]      FIG. 8E  represents the state where the release member  20  is returned to the first position (not shown). 
         [0052]    In  FIG. 8F  the user is pressing the push means  30  (not shown) to start expelling a dose of medicament. This causes the inclined ledge  43  second driver of the second driver  40  to engage the distal inclined surface  52  of the first driver  15 , resulting in rotation of the latter. The second driver is rotationally locked due to the engagement between the inclined ramps  42  and the seat  302 . As the first driver  15  rotates, the plunger rod (not shown) also rotates. The motion of the plunger rod urges a stopper (not shown) to expel medicament through the delivery member. If the push means  30  is dropped by the user at some point during medicament delivery, the engagement between the inclined ledge  43  and the inclined surface  52  is relaxed, but the first driver  15  remains stationary since no force is acting on it. Therefore it is possible to resume and complete the delivery of the dose at any time. The push means  30 , and consequently the second driver  40 , have to be fully depressed, as illustrated in  FIG. 8A , before a subsequent dose can be initialized. 
         [0053]    The present invention is not limited to the above-described preferred embodiment. Various alternatives, modifications and equivalents may be used. Therefore, the above embodiment should not be taken as limiting the scope of the invention, which is defined by the appended claims.