Abstract:
A medicament delivery device includes a housing arranged to accommodate a medicament container, and a drive unit operably arranged to act on an accommodated medicament container for expelling a dose of medicament. The drive unit includes a plunger rod, a force element operably connected to the plunger rod, a connector arranged to releasably hold the plunger rod, an actuator element operably arranged to the connector, and a manually operable actuator arranged to act on the actuator element for releasing the connector when operated. A safety device is arranged to releasably hold the actuator element in a locking position with the connector, preventing unintended release of the plunger rod.

Description:
TECHNICAL AREA 
       [0001]    The present invention relates to a medicament delivery device and in particular to a device arranged with features and functions actuated by a user manually operating the device, wherein the device is arranged with enhanced safety features preventing unintentional activation. 
       BACKGROUND OF INVENTION 
       [0002]    Many medicament delivery devices on the market today are arranged with a number of features that facilitate the use of the device because today&#39;s devices are more and more intended to be handled by the patients themselves. The added functionality may be an advantage when the medicament delivery devices comprise injection needles since many patients feel uncomfortable seeing the needle and also feel reluctant regarding penetration of the needle. In that respect, added functionality may include features such as automatic penetration mechanisms as well as automatic injection mechanisms. 
         [0003]    Many medicament delivery devices that are arranged with automatic features and functions are often also arranged with some sort of actuation member that is operated by a user either indirectly when pressing the device against a dose delivery site or directly by operating an activation button on the device, such as at the distal end thereof. 
         [0004]    Document WO 2012/105898 discloses an activating mechanism comprising an actuator in the form of a button protruding through the distal end of the housing part. The actuator is arranged to act on an actuator member comprised in a power unit of the device. The actuator member is arranged as a ring-shaped element that can be moved axially by the actuator. In one position, the actuator member locks movement of holding elements that are arranged to interact and hold a plunger rod in a tensioned state by a force member. The actuator may then move the actuator member to a release position where the holding elements may be moved out of engagement with the plunger rod, whereby the latter is free to move in the proximal direction by the force member, thereby enabling delivery of a dose of medicament. 
         [0005]    The function of the power unit of WO 2012/105898 has proven to work in most instances. However, in some cases when the device has been accidentally dropped on a hard surface such as a table, a floor or the ground, impact forces may cause the actuator member to move from the locking position to the release position, thereby activating the device such that a dose is delivered unintentionally. 
         [0006]    The dose is then wasted. If the device is a single-use device, then the device has to be discarded without having delivered any medicament to the patient and a new device has to be obtained. Even if the device is re-usable, it has to be reloaded in order to deliver a new dose. Both obtaining a new device or reloading a device is time-consuming and causes stress to a patient, especially in urgent situations. 
         [0007]    There is thus a demand for devices having an increased functionality for minimizing the risk of activation after accidental drops and other types of accidental impacts. 
       BRIEF DESCRIPTION OF INVENTION 
       [0008]    As used herein, the term “liquid” encompasses all fluids, solutions, suspensions, emulsions, oils, gels and so forth, which generally behave as liquids at operating temperatures. The term explicitly includes solid compositions dissolved or dispersed in a liquid carrier. Materials behaving as highly viscous liquids are also included. 
         [0009]    In the present application, when the term “distal part/end” is used, this refers to the part/end of the device, or the parts/ends of the members thereof, which under use of the device is 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 device, or the parts/ends of the members thereof, which under use of the device is located closest to the medicament delivery site of the patient. 
         [0010]    The aim of the present invention is to remedy the drawbacks of the state of the art medicament delivery devices. This aim is obtained with a medicament delivery device according to the features of the independent patent claim. Preferable embodiments of the invention form the subject of the dependent patent claims. 
         [0011]    According to an aspect, it comprises a medicament delivery device comprising a housing. The housing may be in one or several parts wherein the latter case the housing parts may be fixedly attached to each other or movably attached in relation to each other, depending on the application and also type of medicament to be used. The housing, or some of the housing parts, may preferably be arranged to accommodate a medicament container. The medicament container may be of several possible designs, such as syringes, cartridges, ampoules or the like. The medicament container may further be arranged with one or several compartments containing medicament. In the latter case, the compartments may contain medicament components and diluents that are to be mixed before delivery. 
         [0012]    Preferably a drive unit may be operably arranged to act on said medicament container for expelling a dose of medicament. The drive unit may comprise a plunger rod arranged to act on a stopper or the like inside the medicament container. In case of multi-chamber containers, several stoppers may be moved by the plunger rod, both in order to mix the components and also for delivering a dose of medicament. 
         [0013]    A resilient force member may advantageously be operably connected to said plunger rod for driving the plunger rod when delivering a dose of medicament. The force member may have a number of designs within the scope of the invention, such as compression springs, torsion springs, leaf springs, clock springs, gas springs, just to mention some examples. 
         [0014]    The drive unit may further comprise a connection member arranged to releasibly hold said plunger rod when preferably the force member is in a tensioned state. Further, an actuator member may be operably arranged to said connection member as well as a manually operable actuator arranged to act on said actuator member for releasing said connection member when operated. With this solution, the actuator may be operated by a user with his/her hand or fingers, which in turn causes the actuator member to act on the connection member such that the plunger rod is released. Due to the force of the force member, the plunger rod will then act on the stoppers of the medicament container such that a dose of medicament is delivered to the user via a suitable medicament delivery member. The latter may e.g. be an injection needle, a nozzle, a mouth or nasal piece a nebulizer etc. 
         [0015]    According to a favourable solution, it is characterised in a safety device arranged to releasibly hold said actuator member in a locking position with said connection member, preventing unintended release of said plunger rod. With this solution it is ascertained that the actuator member is immovable prior to the manual operation of the actuator by a user. This is a clear advantage and enhanced safety aspect if for example the medicament delivery device should be accidentally dropped on a hard surface such as a table or a floor. Without the safety device, there is a risk that the actuator member may be displaced by impact forces, which in turn could cause the device to be unintentionally triggered and a dose to be wasted. This situation may be critical if the user has only one medicament delivery device at hand and the delivery of a dose of medicament at that time is important or vital. With the safety device according to the preferred solution, the risk is minimized or greatly reduced. 
         [0016]    According to one another aspect, the connection member may comprise generally radially movable connection elements capable of releasibly holding said plunger rod and wherein said actuator member is arranged axially movable from a locking position to a release position of said connection elements. The actuator member will then in the locking position prevent the connection elements from moving in the radial direction, thus ensuring a firm hold of the plunger rod. When moved axially to the release position, the connection elements will be free to move in the radial direction, thereby causing a release of the tensioned plunger rod. 
         [0017]    Preferably the safety device comprises elements arranged to prevent movement of said actuator member from said locking position to said release position until activated. In one solution, the safety elements may be designed as a number of flexible arms protruding distally in a generally longitudinal direction towards said actuator member. This provides a positive blocking action against unintentional movement of the actuator member. 
         [0018]    The safety device may be made of a number of materials having the desired properties. However according to one favourable solution, at least parts of said safety device are made of metal. The use of metal has the advantage that it has a high strength to dimension ratio. Thus, the safety elements may for example be made with reduced thickness in comparison to comparable plastic designs. This further has the advantage that the safety elements occupy less space inside the medicament delivery device, thus not affecting the overall size of the device. It is however to be understood that the solution is not limited to metal, other types of material and combinations of materials may be used depending on application and design criteria. 
         [0019]    Preferably the medicament delivery device may further comprise an activation member operably arranged to, upon manual operation, activate said safety device to allow movement of said actuator member. Thus, in order to make the device ready for delivery of a dose of medicament, the activation member is operated such that the safety device is activated to allow subsequent dose delivery. 
         [0020]    According to a further aspect, said activation member may comprise elements capable of moving said safety elements out of contact with said actuator member. In this respect the solution may comprise protrusions capable of moving said flexible arms outwardly in a radial direction when said activation member is operated. 
         [0021]    These and other aspects of, and advantages with, the present invention will become apparent from the following detailed description of the invention and from the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0022]    In the following detailed description of the invention, reference will be made to the accompanying drawings, of which 
           [0023]      FIG. 1  is a perspective view of one embodiment of a medicament delivery device, 
           [0024]      FIG. 2  is an exploded view of the embodiment of  FIG. 1 , 
           [0025]      FIG. 3  is cross-sectional longitudinal view of the embodiment of  FIG. 1 , 
           [0026]      FIGS. 4-8  are detailed views of components comprised in the embodiment of  FIG. 1 , and 
           [0027]      FIGS. 9-11  are views of different functional states of the device of  FIG. 1 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0028]    The exemplary embodiment of a medicament delivery device  10  is shown in the drawings. It comprises a distal housing part  12  and a proximal housing part  14 . The two housing parts are in the embodiment shown intended and arranged to be interconnected with connection elements. As an example, the connection elements may comprise threads  16 ,  FIG. 1 , on an outer surface of the proximal housing part arranged to cooperate with corresponding threads or thread segments (not shown) on an inner surface of the distal housing part  12 . In this respect it is to be understood that many other types of connection elements may be utilized for attaching the housing parts, such as e.g. bayonet connections or snap-in elements. 
         [0029]    The embodiment shown is designed for handling a multi-chamber medicament container  18 ,  FIG. 2 , and thus the proximal housing part  14  is arranged to accommodate a medicament container, in the embodiment shown a dual chamber container where one chamber contains the medicament in powder form and the other chamber contains a diluent. The two chambers are divided by a movable first stopper  17 . At the distal end of the medicament container a second movable stopper  19  is arranged. The medicament container is further arranged with a proximally directed neck portion,  20  which is intended to fit into a proximally directed neck portion  22  of the proximal housing part  14 ,  FIG. 2 . Further, the outer surface of the neck portion  22  of the proximal housing part  14  is arranged with connection elements for connecting a medicament delivery member  24 . The connection elements may be threads, a bayonet connection, luer-lock connections, snap-on connections etc. Further the medicament delivery member may be an injection needle, a mouth or nasal piece, a nebulizer nozzle, etc. 
         [0030]    The embodiment according to the figures further comprises a drive unit  26 ,  FIG. 2 . The drive unit comprises a generally elongated tubular plunger rod  28 ,  FIGS. 2 and 4 , provided with a longitudinal cavity  30 ,  FIG. 4 , in which a resilient force element  32  is placed. In the embodiment shown the force element  32  is a compression spring, where its proximal end is in contact with an end wall  34  of the cavity  30 ,  FIG. 3 . The distal area of the plunger rod  28  is arranged with two recesses  36  on opposite sides of the plunger rod,  FIG. 4 . These recesses  36  are arranged to cooperate with holding elements  38  on a connector  40  comprised in the drive unit  26 . The holding elements  38  are in the embodiment shown arranged as radially flexible tongues arranged with inwardly protruding hooks  42 ,  FIG. 5 , which hooks fit into the recesses  36  of the plunger rod  28 . 
         [0031]    The connector  40  is further arranged with attachment fixtures  52  for a safety device  54 ,  FIG. 5 . The safety device  54  generally comprises a ring-shaped body  56  of a flexible resilient material such as metal. The ring-shaped body has a diameter corresponding to the diameter of the connector  40  and is arranged to abut a circumferential, distally directed surface  58 ,  FIG. 4 , on the connector  40 . The ring-shaped body  56  is further arranged with attachment tongues  60 , which tongues fit into the attachment fixtures  52  for holding the safety device  54  in place. The ring-shaped body further comprises generally distally directed safety elements, in the embodiment shown arranged as tongues  62 ,  FIGS. 6 and 7 , preferably with a slight inward inclination and where the free ends of the tongues are provided with inwardly directed ledges  64 . 
         [0032]    The distally directed safety elements  62  of the safety device  54  are intended to be in contact with an actuator element  66 ,  FIG. 7 . The actuator element  66  is arranged as a ring-shaped member having a diameter generally corresponding to the outer diameter of the connector  40  and initially positioned such that the actuator element  66  is radially outside the holding elements  38 ,  FIG. 7 , such that radially outward movement of the holding elements is prevented, as will be described in detail below. 
         [0033]    The device further comprises an actuator  68  shaped as a generally tubular body,  FIG. 8 b   . The tubular body is arranged with a distally directed end surface  70 , which will function as a contact surface for a finger of a user. The actuator  68  is further arranged with at least one protrusion  72  at a proximal end and extending outwardly in the radial direction. The protrusions  72  are arranged to come in contact with and act on the actuator element  66  as will be described. The actuator  68  is arranged movable inside a generally tubular activator  74 ,  FIG. 8 a   , which activator  74  is arranged to be connected to a distal end of the distal housing part. The activator  74  is arranged with cut-outs forming distally directed tongues  75 , where the free end of the tongues are arranged with outwardly extending ledges  77 . These ledges  77  cooperate with circumferentially extending ledges (not shown) on an inner surface of the distal housing part  12  such that when the activation member is assembled with the distal end of the distal housing part  12 , the tongues  75  with the ledges  77  will snap behind the circumferential ledges and lock the activator  74  in the longitudinal direction while allowing turning of the activator  74  in relation to the distal housing part  12  as will be described. The body of the activator  74  is further arranged with at least one generally circumferential groove  76 . In the groove  76  a flexible holding arm  78  is arranged in the circumferential direction,  FIG. 8 b   . The free end of the holding arm  78  is arranged with a protrusion  80 . The circumferential groove is connected to a generally longitudinally directed groove  82 . Further, the proximal end of the activator  74  is arranged with at least one release element, in the embodiment shown a proximally directed arm  84 . At the end of the arm a circumferentially directed protrusion  86  is arranged, comprised in the release element, preferably arranged with a wedge-shape, forming a sharp thin edge of the free end of the protrusion  86 . 
         [0034]    The invention is intended to function as follows. When the device is delivered to a user, the proximal housing part  12  is in an extended position in relation to the distal housing part  14 , i.e. the proximal housing part has not been screwed into the distal housing part, as seen in  FIG. 3 . 
         [0035]    The activator  74  is in a rotational position such that the protrusions  72  of the actuator  68  are positioned in the circumferential groove  76  of the activator  74  and the flexible holding arm  78  with its protrusion  80  exerts a holding force on the protrusion  72 ,  FIG. 10 . Thus the actuator  68  is locked from being depressed because the activator is longitudinally fixed. Further, the ring-shaped actuator element  66  is held in position by the distally directed safety elements  62  of the safety device  54 . This ensures that the actuator element  66  cannot be displaced, for example if the device is accidentally dropped on a hard surface. Without the safety device  54 , the actuator element  66  could be moved away from its position, whereby the holding members  38  of the connection elements could move out of contact with the plunger rod, whereby the device could be activated unintentionally. 
         [0036]    When the device is to be used, the first operation is to attach a medicament delivery member  24 . For example an injection needle is attached to the neck portion  22  of the proximal housing part  14 . Then the user has to mix the medicament agent with the diluent agent i.e. a mixing step or sequence. The user then engages the two housing parts  12  and  14  and screw-connects them with each other. This causes the proximal housing part  14  to be axially moved inside the distal housing part  12  due to the connection by the threads  16 , i.e. the proximal and distal housing parts are moved towards each other from the extended position to the retracted position in order to urge the spring-loaded plunger rod  28  into the medicament container  18 , thereby achieving the reconstituted medicament in a manner known in the art. 
         [0037]    When the mixing step has been completed, the medicament has been reconstituted and the device is prepared to be activated. This is done by turning the activator  74  in relation to the distal housing part  12 . This turning will perform two functions. One function is that the protrusions  72  of the actuator  68  become aligned with the longitudinally directed groove  82  through the relative movement of the activator  74  with regard to the actuator  68 , from the locked position past the protrusion  80  of the holding arm  78  and into the longitudinally directed groove  82 ,  FIG. 11 , thereby enabling movement in the proximal direction of the actuator  68 . The second function is that the release elements, i.e. the wedge-shaped protrusions  86  of the activator  74  are moved in contact with and radially inside the safety elements  62  of the safety device  54 . Due to the wedge-shape of the protrusions  86 , the safety elements  62  are forced radially outwards, whereby the free ends of the safety elements  62  are moved out of contact with the actuator element  66 , whereby the latter is free to be moved. 
         [0038]    Now delivery of the reconstituted medicament may be performed. The proximal end of the device, with the medicament delivery member  24 , is positioned at the dose delivery site, which could be an injection site if an injection needle is used, at which site a penetration is performed manually. The user then operates the actuator  68  by pressing it axially towards the proximal direction. This in turn causes the actuator element  66  to be proximally moved due to the contact between the actuator  68  and the actuator element  66 . The proximal movement of the actuator element  66  causes it to slide along the holding elements  38 ,  FIG. 7 . The holding elements  38  are now free to move in the outwardly radial direction, which causes the hooks  42  to move out of contact with its resilient engagement with the recesses  36  of the spring-loaded plunger rod  28 . This in turn releases the spring-loaded plunger rod  28  to move in the proximal direction due to the force of the compressed force element  32 . The movement of the spring-loaded plunger rod  28  forces the stoppers to move proximally inside the medicament container  18  and thereby expel the reconstituted medicament through the medicament delivery member  24 . When the stoppers have reached their end position, i.e. the proximal end position, inside the medicament container  18 , the medicament delivery operation is completed. 
         [0039]    It is to be understood that the elements and mechanisms described above and shown in the drawings are only examples of structures that may be replaced by other elements and/or mechanisms displaying the same or similar function for obtaining the desired end result. It is further 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.